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| acid anhydride | literally "an acid without water" (See page(s) 250) |
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| acid deposition | deposition of either wet forms or dry forms such as rain, snow, fog, and cloud-like suspensions of microscopic water droplets often more acidic and damaging than acid rain (See page(s) 246) |
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| acid rain | rain that is more acidic than "normal" rain and that has a lower pH (See page(s) 245) |
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| acid | a compound that releases hydrogen ions, H+, in aqueous solution (See page(s) 240) |
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| acid-neutralizing capacity (ANC) | capacity of a lake or other body of water to resist a decrease in pH (See page(s) 269) |
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| activation energy | energy necessary to initiate a chemical reaction (See page(s) 179) |
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| active site | region of an enzyme molecule where its catalytic effect occurs (See page(s) 510) |
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| addition polymerization | type of polymerization in which the monomers add to the growing chain in such a way that the polymer contains all the atoms of the monomer. No other products are formed. (See page(s) 372) |
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| aerosols | particles, both liquid and solid, that remain suspended in the air rather than settling out (See page(s) 35) |
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| albedo | ratio of electromagnetic radiation reflected relative to the amount of radiation incident on a surface (See page(s) 131) |
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| alkane | a hydrocarbon with only single bonds between the carbon atoms (See page(s) 171) |
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| allotropes | two or more forms of the same element that differ in their chemical structure and therefore in their properties (See page(s) 57) |
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| alpha particle (α) | positively charged (2+) particle consisting of two protons and two neutrons (the nucleus of a helium atom) (See page(s) 296) |
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| ambient air | the outside air, that is, the air surrounding or encircling us (See page(s) 18) |
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| amino acid | monomer from which our body builds proteins. Each amino acid molecule contains two functional groups: an amine group (—NH2) and a carboxylic acid group (—COOH). (See page(s) 385) |
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| amino acid residue | amino acid that was once incorporated into a peptide chain (See page(s) 468) |
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| amorphous region | in a polymer, a region in which the long polymer molecules are in a random, disordered arrangement (See page(s) 377) |
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| anaerobic bacteria | bacteria that can function without the use of molecular oxygen (See page(s) 127) |
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| anion | negatively charged ion (See page(s) 209) |
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| anode | electrode where oxidation takes place (See page(s) 333) |
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| antioxidant | compound added to foods, drugs, and cosmetics to minimize the oxidation of unsaturated oils and fats that can cause rancidity, color loss, and flavor changes (See page(s) 486) |
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| aqueous solution | solution in which water is the solvent (See page(s) 199) |
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| aquifer | great pool of water trapped in sand and gravel 50–500 ft below the surface (See page(s) 197) |
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| atom | smallest unit of an element that can exist as a stable, independent entity (See page(s) 25) |
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| atomic mass | average mass of an atom of an element compared with an atomic mass of exactly 12 amu for carbon-12 121; mass (in grams) of the same number of atoms found in exactly 12 g of carbon-12 (See page(s) 122) |
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| atomic number | number of protons in an atom of that element (See page(s) 60) |
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| Avogadro's number | number of atoms in exactly 12 g of carbon-12 (See page(s) 122) |
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| background radiation | the radiation, on average, that exists at a particular location, usually due to natural sources (See page(s) 304) |
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| basal metabolism rate (BMR) | minimum amount of energy required daily to support basic body functions (See page(s) 479) |
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| base | compound that produces hydroxide ions, OH_, in aqueous solution (See page(s) 242) |
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| battery | device consisting of one or more cells that can produce a direct current by converting chemical energy to electrical energy (See page(s) 332) |
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| beta particle (ß) | high-speed electron emitted from a nucleus (See page(s) 296) |
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| biomass | general term for plant matter such as trees, grasses, agricultural crops or other biological material (See page(s) 179) |
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| blowing agent | either a gas or a substance capable of producing a gas used to manufacture a foamed plastic (See page(s) 381) |
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| bond energy | amount of energy that must be absorbed to break a specific chemical bond (See page(s) 160) |
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| breeder reactor | a nuclear reactor that can produce more fissionable fuel (usually Pu-239) than it consumes (usually U-235) (See page(s) 312) |
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| calibration graph | graph made by carefully measuring the absorbencies of several solutions of known concentration for the species being analyzed (See page(s) 226) |
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| calorie | formerly defined as the amount of heat necessary to raise the temperature of exactly 1 g of water by 1°C. Now redefined as exactly 4.184 J. 1 (See page(s) 52) |
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| calorimeter | device with which the quantity of heat energy released in a combustion reaction can be determined experimentally (See page(s) 158) |
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| carbohydrates | compounds containing carbon, hydrogen, and oxygen, the last two elements in the same 2:1 atomic ratio as found in water (See page(s) 465) |
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| carbon nanotubes | nano-sized tubes of pure carbon with wall thicknesses as thin as a single atom (See page(s) 430) |
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| carbon sink | natural reservoir that removes CO2 from the atmosphere (See page(s) 121) |
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| carcinogen | compound capable of causing cancer (See page(s) 219) |
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| carcinogenic | capable of causing cancer (See page(s) 43) |
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| catalyst | chemical substance that participates in a chemical reaction and influences its rate or speed without undergoing permanent change (See page(s) 36, 84) |
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| catalytic converter | device installed in the exhaust stream of an engine to reduce emissions (See page(s) 36) |
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| catalytic cracking | catalysts used to promote molecular breakdown at lower temperatures than thermal cracking (See page(s) 175) |
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| cathode | electrode where reduction takes place. The cathode receives the electrons sent from the anode through the external circuit. (See page(s) 333) |
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| cation | positively charged ion (See page(s) 209) |
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| chain reaction | term that generally refers to any reaction in which one of the products becomes a reactant (See page(s) 288) |
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| Chapman cycle | set of natural steadystate reactions for stratospheric ozone (See page(s) 74) |
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| Chargaff's rules | observation that in every species, the percent of adenine almost exactly equals the percent of thymine. Similarly, the percent of guanine is essentially identical to the percent of cytosine. Put more simply: %A = %T and %G = %C. (See page(s) 501) |
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| chemical equation | representation of a chemical reaction using chemical formulas (See page(s) 29) |
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| chemical formula | symbolic way to represent the elementary composition of a substance, indicating the kinds and numbers of atoms present in a molecule (See page(s) 26, 408) |
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| chemical reaction | process whereby reactants are transformed into products (See page(s) 29) |
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| chemical symbol | one- or two-letter abbreviation for an element. Also called atomic symbol (See page(s) 21) |
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| chiral (optical) isomers | compounds with the same chemical formula but different three-dimensional molecular structures and different interaction with plane polarized light (See page(s) 423) |
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| chlorofluorocarbons (CFCs) | compounds composed only of the elements chlorine, fluorine, and carbon (See page(s) 82) |
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| chromosomes | the 46 self-replicating, rod-shaped strands of deoxyribonucleic acid (DNA) and associated proteins found in the nucleus of cells that contain the hereditary information necessary for life (See page(s) 498) |
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| clone | collection of cells or molecules identical to an original cell or molecule (See page(s) 515) |
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| codon | sequence of three adjacent nucleotides that determines the insertion of a specific amino acid during protein synthesis or that signals the starting and stopping of protein synthesis (See page(s) 507) |
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| coenzyme | molecule that works in conjunction with an enzyme to enhance the enzyme's activity (See page(s) 474) |
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| combinatorial chemistry | systematic creation of large numbers of molecules in "libraries" that can be rapidly screened in the lab for biological activity and the potential for becoming new drugs (See page(s) 422) |
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| combustion | chemical process in which a fuel combines rapidly with oxygen to release energy and form products (See page(s) 29,158) |
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| complex carbohydrates | polysaccharides such as starch, cellulose, and glycogen (See page(s) 466) |
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| compound | pure substance made up of two or more elements in a fixed, characteristic chemical combination (See page(s) 24) |
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| concentration | ratio of amount of solute to amount of solution (See page(s) 201) |
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| condensation polymerization | a type of polymerization in which a small molecule such as water is split out (eliminated) when the monomers join to form a polymer (See page(s) 383) |
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| condensed structural formula | chemical formula in which bonds are not drawn out explicitly, but simply understood to contain an appropriate number of bonds (See page(s) 408) |
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| conductivity meter | an apparatus that produces a signal to indicate that electricity is being conducted (See page(s) 208) |
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| control rods | rods composed primarily of an excellent neutron absorber such as cadmium or boron that can be positioned in a nuclear reactor to absorb fewer or more neutrons, thereby regulating the rate of fission (See page(s) 292) |
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| copolymer | polymer built from two or more different monomers (See page(s) 383) |
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| covalent bond | a chemical bond in which two electrons are shared by the atoms involved (See page(s) 63) |
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| cracking | chemical process by which large molecules are broken into smaller ones, such as those suitable for use in gasoline (See page(s) 174) |
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| criteria pollutants | air pollutants for which EPA has set permissible levels based on their effects on human health and on the environment (See page(s) 10) |
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| critical mass | amount of fissionable fuel required to sustain an atomic chain reaction (See page(s) 288) |
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| crystalline region | in a polymer, a region in which the long polymer molecules are arranged neatly and tightly in a regular pattern (See page(s) 377) |
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| curie (Ci) | unit of radioactivity, equal to 3.7 ×1010 disintegrations/s and roughly equivalent to the level of radioactivity from 1 g of radium (See page(s) 305) |
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| current | rate of electron flow (See page(s) 335) |
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| denitrification | process of converting nitrate ions, typically in soil, to nitrogen gas (See page(s) 266) |
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| density | the ratio of mass per unit volume (See page(s) 207) |
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| deoxyribonucleic acid (DNA) | molecule that carries genetic information in all species (See page(s) 498) |
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| depleted uranium | contains almost entirely U-238 (99.8%) and has been depleted of most of the U-235 that it once naturally contained (See page(s) 317) |
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| desalination | any process that removes ions from salty water (See page(s) 230) |
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| diatomic molecule | molecule that contains two atoms (See page(s) 26) |
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| dietary supplement | vitamins, minerals, amino acids, enzymes, herbs, and other botanicals (See page(s) 440) |
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| dipeptide | a compound formed from two amino acids (See page(s) 468) |
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| dirty bomb | " device that employs a conventional explosive to disperse a radioactive substance (See page(s) 319) |
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| disaccharide | "double sugar" formed by joining two monosaccharide units (See page(s) 465) |
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| dispersion forces | attractions between molecules that result from a distortion of the electron cloud that causes an uneven distribution of the negative charge (See page(s) 375) |
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| distillation | separation process in which a solution is heated to its boiling point and the vapors of the various components are condensed and collected (See page(s) 171, 230) |
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| distributed generation | placing powergenerating modules of 30 megawatts or less near the end user (See page(s) 345) |
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| "doping" | process of intentionally adding small amounts of other elements to pure silicon (See page(s) 355) |
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| double bond | covalent bond consisting of two pairs of shared electrons (See page(s) 66) |
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| double helix | spiral consisting of two strands that coil around a central axis (See page(s) 503) |
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| effective stratospheric chlorine | chlorine- and bromine-containing gases in the stratosphere (See page(s) 89) |
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| electricity | flow of electrons from one region to another that is driven by a difference in potential energy (See page(s) 332) |
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| electrode | electrical conductor placed in the cell as sites for chemical reactions (See page(s) 332) |
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| electrolysis | process of passing a direct current of electricity of sufficient voltage through water to decompose it into H2 and O2 (See page(s) 348) |
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| electrolyte | conducting solute in solution (See page(s) 209) |
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| electrolytic cell | device in which electrical energy is converted to chemical energy (See page(s) 332) |
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| electromagnetic spectrum | continuum of waves ranging from very long and low-energy radio waves to very short and high-energy X-rays and gamma rays (See page(s) 69) |
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| electron | subatomic particle with a much smaller mass than a proton or neutron and a negative electrical charge equal in magnitude to that of a proton, but opposite in sign (See page(s) 60) |
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| electronegativity (EN) | measure of an atom's attraction for the electrons it shares in a covalent bond (See page(s) 204) |
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| element | pure substance that cannot be broken down into simpler ones by any chemical means (See page(s) 21) |
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| endothermic | term applied to any chemical or physical change that absorbs energy (See page(s) 160) |
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| energy | the capacity to do work or supply heat (See page(s) 152) |
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| "enhanced greenhouse effect" | process in which atmospheric gases trap and return more than 80% of the heat energy radiated by the Earth (See page(s) 105) |
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| enriched uranium | uranium that has a higher percent of U-235 than its natural abundance of about 0.7% (See page(s) 316) |
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| entropy | randomness in position or energy level (See page(s) 157) |
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| enzyme | protein that acts as a biochemical catalyst, influencing the rate of a chemical reaction (See page(s) 417) |
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| essential amino acid | an amino acid that is required for protein synthesis but that must be obtained from the diet because the body cannot synthesize it (See page(s) 470) |
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| exothermic | term applied to any chemical or physical change accompanied by the release of heat (See page(s) 158) |
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| exposure | amount of a substance encountered, generally in reference to human contact with a toxic substance or a disease-causing organism (See page(s) 17) |
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| fat | triglyceride that is solid at room temperature (See page(s) 459) |
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| fatty acid molecule | molecule with two structural features: a nonpolar long hydrocarbon chain generally containing an even number of carbon atoms (typically 12 to 24) and a polar carboxylic acid group at the end of the chain (See page(s) 457) |
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| first law of thermodynamics | the statement that energy is neither created nor destroyed, also called the law of conservation of energy (See page(s) 153) |
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| food irradiation | process of subjecting food to high-energy ionizing radiation to kill or reduce the levels of undesirable contaminants such as bacteria, spores, and insects (See page(s) 487) |
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| forcings | factors that affect the annual global mean surface temperature (See page(s) 131) |
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| free radical | unstable chemical species with one or more unpaired electrons (See page(s) 80) |
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| freebase | nitrogen-containing molecule in which the nitrogen is in possession of its lone pair of electrons (See page(s) 414) |
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| frequency | number of waves passing a fixed point in one second (See page(s) 68) |
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| fuel cell | galvanic cell that produces electricity by converting the chemical energy of a fuel directly into electricity without burning the fuel (See page(s) 340) |
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| functional group | distinctive arrangement of groups of atoms that impart characteristic physical and chemical properties to the molecules that contain them (See page(s) 382, 411) |
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| galvanic cell | device that converts the energy released in a spontaneous chemical reaction into electrical energy (See page(s) 332) |
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| galvanized iron | iron coated with zinc (See page(s) 260) |
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| gamma ray (γ) | high-energy, shortwavelength photon emitted from the nucleus with no charge or mass (See page(s) 296) |
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| gaseous diffusion | a process used to separate gases with different molecular weights by forcing them through a series of permeable membranes (See page(s) 316) |
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| gene | short piece of DNA that codes for the production of proteins, giving an organism its particular inherited characteristics (See page(s) 498) |
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| generic drug | medication that is the chemical equivalent of a pioneer drug, but that cannot be marketed until the patent protection on the pioneer drug has run out after 20 years (See page(s) 435) |
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| global atmospheric lifetime | time required for a gas added to the atmosphere to be removed. Also referred to as the "turnover time." (See page(s) 126) |
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| global warming | popular term used to describe the increase in average global temperatures (See page(s) 101) |
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| global warming potential (GWP) | number that represents the relative contribution of a molecule of an atmospheric gas to global warming (See page(s) 128) |
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| green chemistry | the designing of chemical products and processes that reduce or eliminate the use or generation of hazardous substances (See page(s) 38) |
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| greenhouse effect | process by which atmospheric gases trap and return a major portion of the heat (infrared radiation) radiated by the Earth (See page(s) 103) |
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| greenhouse gases | those gases capable of absorbing and re-emitting infrared radiation (See page(s) 102) |
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| groundwater | water pumped from wells that have been drilled into underground aquifers (See page(s) 197) |
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| group | vertical column in the periodic table (See page(s) 23) |
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| half-life (t1/2) | time required for half the nuclei in a sample of a radioisotope to undergo radioactive decay (See page(s) 309) |
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| half-reaction | type of chemical equation that shows the electrons either lost or gained (See page(s) 332) |
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| halons | compounds similar to CFCs, in which bromine or fluorine atoms replace some or all of the chlorine atoms (See page(s) 82) |
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| HDL (high-density lipoprotein) | called the "good" lipoproteins because it is more effective than LDL in transporting cholesterol through the blood (See page(s) 464) |
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| heat | energy that flows from a hotter to a colder object (See page(s) 152) |
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| heat of combustion | quantity of heat energy given off when a specified amount of a substance burns in oxygen (See page(s) 159) |
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| high-level radioactive waste (HLW) | products of nuclear reactions that have high levels of radioactivity and, because of the long half-lives of the radioisotopes involved, require essentially permanent isolation from the biosphere (See page(s) 311) |
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| hormesis | concept that low doses of a harmful substance (such as radiation) may actually be benefi- cial (See page(s) 308) |
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| hormone | chemical messengers produced by the body's endocrine glands (See page(s) 416) |
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| Human Genome Project | international effort to map all the genes in the human organism (See page(s) 512) |
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| hybrid vehicle | vehicle that combines conventional gasoline engines with battery technology (See page(s) 338) |
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| hydrocarbon | compound that contains only the elements hydrogen and carbon (See page(s) 28, 171) |
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| hydrochlorofluorocarbons (HCFCs) | compounds of hydrogen, chlorine, fluorine, and carbon (See page(s) 91) |
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| hydrofluorocarbons (HFCs) | compounds of hydrogen, fluorine, and carbon (See page(s) 92) |
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| hydrogen bond | electrostatic attraction between a hydrogen atom bearing a partial positive charge in one molecule and an O, N, or F atom bearing a partial negative charge in a neighboring molecule (See page(s) 206) |
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| hydrogenation | process in which hydrogen gas, in the presence of a metal catalyst, is added to a double bond and converts it to a single bond (See page(s) 462) |
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| hydronium ion (H3O+) | water molecule plus a proton (See page(s) 343) |
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| hygroscopic | describes a substance that readily absorbs water from the atmosphere and retains it (See page(s) 262) |
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| infrared (IR) | heat radiation; the region of the electromagnetic spectrum with wavelengths longer than those of red visible light (See page(s) 69) |
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| intermolecular attractive force | attraction between two molecules resulting from the interactions of their electron clouds and nuclei (See page(s) 374) |
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| intermolecular force | force that occurs between molecules (See page(s) 206) |
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| intramolecular force | force that exists within a molecule (See page(s) 204) |
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| ion | atom or group of atoms that has acquired a net electrical charge as a result of gaining or losing one or more electrons (See page(s) 209) |
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| ionic bond | chemical bond formed by the attraction between oppositely charged ions (See page(s) 209) |
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| ionic compound | compound composed of electrically charged ions that are present in fixed proportions and are arranged in a regular, geometric pattern (See page(s) 209) |
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| isomers | molecules with the same chemical formula (same number and kinds of atoms), but with different structures and properties (See page(s) 175, 408) |
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| isotopes | two or more atoms of the same element. Isotopes have the same number of protons but differ in the number of neutrons, and hence in mass. (See page(s) 62) |
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| kinetic energy | energy of motion (See page(s) 153) |
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| law of conservation of matter and mass | in a chemical reaction, matter and mass are conserved (See page(s) 30) |
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| LDL (low-density lipoprotein) | called "bad" lipoprotein because it is less effective than HDL in transporting cholesterol through the blood (See page(s) 464) |
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| lead compound | drug (or a modified version of that drug) that shows high promise for becoming an approved drug (See page(s) 422) |
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| Lewis structure | representation of an atom or molecule that shows its outer electrons (See page(s) 63) |
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| line-angle drawing | simplified version of a structural formula that is most useful for representing larger molecules (See page(s) 410) |
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| linear, nonthreshold model | model that assumes that the adverse effects of radiation increase linearly with dose, with radiation being harmful at all doses, even low ones (See page(s) 307) |
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| lipid | class of compounds that includes not only the edible fats and oils but also diverse materials such as cholesterol and other steroids (See page(s) 457) |
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| liter (L) | volume occupied by 1000 g of water at 4 °C (See page(s) 201) |
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| low-level radioactive waste (LLW) | waste that is contaminated with smaller quantities of radioactive materials than HLW and specifically excludes spent nuclear fuel (See page(s) 311) |
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| macrominerals | seven elements (Ca, P, Cl, K, S, Na, and Mg) that are necessary for life but are not nearly as abundant as O, C, H, or N (See page(s) 475) |
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| macromolecules | molecules of high molecular mass that have characteristic properties because of their large size (See page(s) 370) |
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| macronutrients | fats, carbohydrates, and proteins that provide essentially all of the energy and most of the raw material for repair and synthesis (See page(s) 455) |
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| malnutrition | condition caused by a diet lacking in the proper mix of nutrients, even though the energy content of the food eaten may be adequate (See page(s) 454) |
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| mass number | sum of the number of protons and neutrons in the nucleus of an atom (See page(s) 62) |
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| maximum contaminant level (MCL) | legal limit for the concentration of a contaminant (See page(s) 220) |
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| maximum contaminant level goal (MCLG) | maximum level of a contaminant in drinking water at which no known or anticipated adverse effect on a person's health would occur (See page(s) 219) |
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| mesosphere | region of the atmosphere above the stratosphere; found at an altitude starting about 50 km (See page(s) 20) |
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| metallic bonding | "electron sea" model, in which outermost (valence) electrons are shared among all the atoms in the substance (See page(s) 353) |
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| metalloids | elements between metals and nonmetals on the periodic table that do not fall cleanly into either group. Sometimes called semimetals. (See page(s) 23) |
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| metals | elements that are shiny and conduct electricity and heat well. They tend to lose their valence electrons to form cations. (See page(s) 23, 210) |
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| microcell | very tiny fuel cell (See page(s) 345) |
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| microgram (µg) | a millionth (10-6) of a gram (See page(s) 18) |
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| micrometer (m) | a millionth (10-6) of a meter. Sometimes simply referred to as a micron. (See page(s) 10) |
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| microminerals | quantities of Fe, Cu, and Zn that the body requires in lesser amounts (See page(s) 475) |
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| micronutrients | substances needed only in miniscule amounts, but essential for the body to produce enzymes, hormones, and other substances needed for proper growth and development (See page(s) 472) |
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| microtubule | nano-sized hollow cylinder with outer diameter between 20 nm and 30 nm (See page(s) 429) |
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| mineral | naturally occurring element or compound that usually has a definite chemical composition, a crystalline structure, and is formed as a result of geological processes (See page(s) 199) |
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| mixture | physical combination of two or more substances present in variable amounts (See page(s) 11) |
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| moderator | material that slows the neutrons in a nuclear reactor, making them more effective in producing fission (See page(s) 293) |
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| molar mass | mass of one Avogadro's number, or "mole," of whatever particles are specified (See page(s) 124) |
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| molarity (M) | number of moles of solute present in 1 L of solution (See page(s) 202) |
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| mole | an Avogadro's number of objects (See page(s) 123) |
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| molecule | two or more atoms held together by chemical bonds in a certain spatial arrangement (See page(s) 26) |
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| monomer | (from mono meaning "one" and meros meaning "unit"). Small molecules used to synthesize polymers. (See page(s) 370) |
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| monosaccharide | single sugar (See page(s) 465) |
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| monounsaturated | property of fats in which only one double bond exists between carbon atoms per molecule. Oleic acid is an example. (See page(s) 459) |
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| municipal solid waste (MSW) | garbage, that is, everything you discard or throw into your trash, including food scraps, grass clippings, and old appliances. MSW does not include industrial waste or waste from construction sites. (See page(s) 388) |
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| nanomedicine | the union of nanoscale technology and medical treatment (See page(s) 429) |
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| nanometer (nm) | a billionth (10-9) of a meter (m) (See page(s) 69) |
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| nanotechnology | technology at the atomic and molecular (nanometer) scale: 1 nanometer (nm) =1 ×10-9 m (See page(s) 25) |
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| nanotubes (nanocapsules) | thin, singlewalled tubes that may be synthetic or partially synthetic (bionanotubes) (See page(s) 429) |
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| neutral solution | a solution that is neither acidic nor basic; that is, one that has equal concentrations of H+ and OH- (See page(s) 244) |
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| neutralization | chemical reaction in which the hydrogen ions from an acid combine with the hydroxide ions from a base to form molecules of water (See page(s) 243) |
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| neutron | electrically neutral subatomic particle with the same mass as a proton (See page(s) 60) |
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| nitrification | process of converting ammonia, typically in soil, to nitrate ions (See page(s) 266) |
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| nitrogen cycle | set of chemical pathways whereby nitrogen moves through the biosphere (See page(s) 267) |
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| nitrogen saturation | process by which an area is overloaded with "nitrogen"; that is, when the reactive forms of nitrogen entering an ecosystem exceed the system's capacity to absorb the nitrogen (See page(s) 270) |
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| nitrogen-fixing bacteria | bacteria that remove nitrogen from the air and convert it to ammonia (See page(s) 266) |
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| noble gases | elements that are inert and do not readily undergo chemical reactions (See page(s) 24) |
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| nonelectrolyte | nonconducting solute in solutions (See page(s) 209) |
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| nonmetals | elements with varied appearances that do not conduct electricity or heat well. Nonmetals tend to gain electrons to form anions. (See page(s) 23, 210) |
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| n-type semiconductor | in which there are freely-moving negative charges, the electrons (See page(s) 355) |
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| nuclear fission | the splitting of a large nucleus into smaller ones with the release of energy and neutrons (See page(s) 287) |
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| nuclear transfer | laboratory procedure in which a cell's nucleus is removed and placed into an egg cell that has had its own nucleus removed. The genetic information from the donor nucleus controls the resulting cell, which can be induced to form embryos. (See page(s) 520) |
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| nucleotide | combination of a base, a deoxyribose molecule, and a phosphate group (See page(s) 500) |
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| nucleus | minuscule but highly dense region at the center of an atom that is composed of protons and neutrons (See page(s) 60) |
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| octet rule | the generalization that electrons in many molecules are arranged so that every atom (except hydrogen) shares in eight electrons (See page(s) 64) |
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| oils | triglycerides that are liquid at room temperature (See page(s) 459) |
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| organic chemistry | the branch of chemistry devoted to the study of carbon compounds (See page(s) 407) |
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| organic compound | compound that contains mainly carbon and hydrogen (See page(s) 36) |
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| osmosis | natural tendency for a solvent to move through a membrane from a region of higher solvent concentration to a region of lower solvent concentration (See page(s) 230) |
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| outer (valence) electrons | electrons that help account for many of the observed trends in chemical properties (See page(s) 61) |
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| oxidation half-reaction | type of chemical equation that shows the reactant that loses electrons (See page(s) 332) |
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| oxygenated gasolines | blends of petroleum-derived hydrocarbons with added oxygen-containing compounds such as MTBE, ethanol, or methanol (CH3OH) (See page(s) 177) |
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| ozone layer | region of the stratosphere with the maximum ozone concentration (See page(s) 58) |
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| parts per billion (ppb) | 1 part out of a billion parts, unit of concentration. 1 ppb is 1000 times less concentrated than 1 ppm. (See page(s) 19, 202) |
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| parts per million (ppm) | 1 part out of a million parts, unit of concentration. 1 ppm is 10,000 times less concentrated than 1 part per hundred (pph). (See page(s) 13, 201) |
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| peptide bond | covalent bond that forms when the —COOH group of one amino acid reacts with the —NH2 group of another, thus joining the two amino acids (See page(s) 386) |
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| percent | parts per hundred; sometimes abbreviated as pph (See page(s) 11, 201) |
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| periodic properties | regular recurrence of certain chemical aspects of atoms that is demonstrated with increasing atomic number. These attributes are repeated at regular intervals in the periodic table. (See page(s) 61) |
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| periodic table | an orderly arrangement of all the elements based on similarities in their properties (See page(s) 22) |
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| pH | a number, usually between 0 and 14, that indicates the acidity of a solution (See page(s) 245) |
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| pharmacophore | three-dimensional arrangement of atoms or groups of atoms responsible for the biological activity of a drug molecule (See page(s) 421) |
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| photons | individual bundles of energy (See page(s) 71) |
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| photovoltaic cell (solar cell) | a device that converts radiant energy directly to electrical energy (See page(s) 353) |
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| plasmid | ring of DNA (See page(s) 514) |
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| plasticizer | compound added in small amounts to polymers to make them softer and more pliable (See page(s) 380) |
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| PM10 | particulate matter with an average diameter of 10 µm or less (on the order of 0.0004 in) (See page(s) 10) |
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| PM2.5 | particulate matter with an average diameter less than 2.5 µm, also called fine particles (See page(s) 10) |
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| polar covalent bond | covalent bond in which the electrons are not equally shared, but rather displaced toward the more electronegative atom (See page(s) 204) |
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| polar stratospheric clouds (PSCs) | thin stratospheric clouds composed of a small amount of frozen water vapor (See page(s) 86) |
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| polyamide | condensation polymer that contains the amide functional group (See page(s) 386) |
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| polyatomic ion | ion that is made up of two or more atoms covalently bound together (See page(s) 213) |
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| polyatomic molecule | molecule consisting of three or more atoms (See page(s) 65) |
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| polymer | large molecule built from monomers consisting of a long chain or chains of atoms covalently bonded together (See page(s) 370) |
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| polysaccharide | polymer made up of thousands of glucose units (See page(s) 466) |
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| polyunsaturated hydrocarbon | fatty acids that contain more than one double bond between carbon atoms per molecule (See page(s) 459) |
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| postconsumer content | used material that would otherwise have been discarded as waste (See page(s) 396) |
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| potable water | water that is fit for human consumption (See page(s) 195) |
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| potential energy | energy that is stored. Also called the energy of position. (See page(s) 153) |
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| power density | energy capacity per unit of fuel cell mass (See page(s) 343) |
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| preconsumer content | waste left over from the manufacturing process itself, such as scraps and clipping (See page(s) 396) |
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| primary coolant | liquid that comes in direct contact with the nuclear reactor core to carry away heat (See page(s) 293) |
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| primary structure | the unique identity and sequence of the amino acids that make up each protein (See page(s) 508) |
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| product | substance formed from reactants as a result of a chemical reaction (See page(s) 29) |
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| protein | polyamides (polypeptides) built from a long chain of amino acids (See page(s) 468, 506) |
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| protein complementarity | combining foods that complement essential amino acid content so that the total diet provides a complete supply of amino acids (See page(s) 471) |
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| proton | positively charged subatomic particle having the same mass as a neutron (See page(s) 60) |
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| p-type semiconductor | semiconductor that contains freely moving positive charges, or "holes" (See page(s) 355) |
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| quantized | noncontinuous energy distribution that consists of many individual steps (See page(s) 71, 118) |
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| racemic mixture (±) | mixture consisting of equal amounts of each optical isomer of a compound (See page(s) 425) |
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| rad (radiation absorbed dose) | unit of radiation that indicates absorption of 0.01 J of radiant energy per kilogram of tissue (See page(s) 305) |
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| radiant energy | the entire collection of different wavelengths, each with its own energy (See page(s) 69) |
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| radiation sickness | illness characterized by early symptoms of anemia, nausea, malaise, and susceptibility to infection that results from a large exposure to radiation (See page(s) 304) |
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| radioactive decay series | characteristic pathway of radioactive decay that begins with a radioisotope and progresses through a series of steps to eventually produce a stable isotope (See page(s) 299) |
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| radioactivity | spontaneous emission of radiation by certain elements (See page(s) 296) |
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| reactant | starting material that is transformed into a product during a chemical reaction (See page(s) 29) |
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| reactive nitrogen | compounds of nitrogen that are biologically active, chemically active, or active with light in our atmosphere (See page(s) 265) |
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| recombinant DNA | DNA that has incorporated DNA from another organism (See page(s) 514) |
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| recyclable product | product that can be recycled. They do not necessarily contain any recycled materials. (See page(s) 396) |
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| recycled-content product | product made from materials that otherwise would have been in the waste stream (See page(s) 396) |
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| reduction half-reaction | type of chemical equation that shows the reactant that gains electrons (See page(s) 332) |
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| reforming | process using heat, pressure, and catalysts to rearrange the atoms within molecules (See page(s) 344) |
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| reformulated gasolines (RFGs) | oxygenated gasolines that also contain a lower percentage of certain more volatile hydrocarbons such as benzene found in nonoxygenated conventional gasoline (See page(s) 177) |
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| rem (roentgen equivalent man) | unit of equivalent dose that indicates the damage done to human tissue by a particular dose of radiation. A rem is the number of rads multiplied by the quality factor Q. (See page(s) 305) |
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| replication | process of cell reproduction in which the cell copies and transmits its genetic information to its progeny (See page(s) 504) |
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| resonance forms | Lewis structures that represent hypothetical extremes of electron arrangements in a molecule (See page(s) 67) |
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| respiration | process by which humans and animals exchange the oxygen necessary for metabolism with the carbon dioxide produced by it (See page(s) 166) |
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| reverse osmosis | purification process that uses pressure to force the movement of a solvent through a semipermeable membrane from a region of high solute concentration to a region of lower solute concentration (See page(s) 231) |
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| risk assessment | organized evaluation of scientific data to predict the probability of an occurrence (See page(s) 17) |
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| saturated hydrocarbon | hydrocarbon chain containing only single bonds between the carbon atoms (See page(s) 459) |
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| scientific notation | system for writing numbers as the product of a number and 10 raised to the appropriate power (See page(s) 18) |
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| second law of thermodynamics | the statement that the entropy of the universe is constantly increasing (See page(s) 157) |
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| secondary coolant | water in the steam generators of a nuclear reactor core that does not come in contact with the core (See page(s) 293) |
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| secondary pollutant | pollutant produced from chemical reactions among two or more other pollutants (See page(s) 40) |
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| secondary structure | periodic, localized arrangement of the backbone segments of a protein chain (See page(s) 508) |
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| semiconductor | material that does not normally conduct electricity or heat well, but that can do so under certain conditions, such as exposure to sunlight (See page(s) 353) |
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| sequestration | process of keeping some things apart. Chemically this is accomplished by forming stable bonds between the sequestering agent and the substance "trapped." (See page(s) 136) |
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| sievert (Sv) | international unit equal to 100 rem (See page(s) 305) |
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| significant figure | a number that correctly represents the accuracy with which an experimental quantity is known (See page(s) 46) |
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| single covalent bond | a bond formed when only one pair of shared electrons forms the linkage between atoms (See page(s) 64) |
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| solute | substance that dissolves in a solvent (See page(s) 199) |
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| solution | homogeneous mixture of uniform composition (See page(s) 199) |
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| solvent | substance capable of dissolving other substances (See page(s) 199) |
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| specific heat | quantity of heat energy that must be absorbed to increase the temperature of 1 g of a substance by 1°C (See page(s) 208) |
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| spent nuclear fuel (SNF) | radioactive material remaining in fuel rods after they have been used to generate power in a nuclear reactor. SNF is regulated as high-level radioactive waste (HLW). (See page(s) 312) |
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| steady state | condition in which a dynamic system is in balance so that no net change occurs in the concentration of the major species involved (See page(s) 74) |
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| stem cells | identical, undifferentiated cells that, by successive divisions, can give rise to specialized ones like blood cells (See page(s) 521) |
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| steroids | class of naturally occurring or synthetic fat-soluble organic compounds that share a common carbon skeleton arranged in four rings (See page(s) 427) |
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| storage battery | battery that is capable of storing electrical energy (See page(s) 336) |
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| stratosphere | region of the atmosphere above the troposphere; includes the ozone layer (See page(s) 20) |
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| structural formula | chemical representation that shows the atoms and their arrangement with respect to one another in a molecule. A structural formula replaces each bonded electron pair in a Lewis structure with a line. (See page(s) 64, 408) |
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| structure–activity relationship (SAR) study | systematic changes made to a drug molecule and assessment of the resulting changes in activity (See page(s) 420) |
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| substituent | atom or functional group substituted for a hydrogen atom (See page(s) 415) |
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| substrate | molecule (or molecules) being acted on, often catalytically by an enzyme (See page(s) 421, 510) |
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| surface water | water from lakes, rivers, and reservoirs (See page(s) 197) |
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| temperature | property of matter that determines the direction of heat flow (See page(s) 152) |
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| tertiary structure | overall shape or conformation of a protein molecule (See page(s) 510) |
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| tetrahedron | four-cornered figure with four equal triangular sides (See page(s) 111) |
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| thermal cracking | heating of starting materials to a high temperature (See page(s) 175) |
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| thermoplastic polymer | plastics that can be melted and reshaped over and over again (See page(s) 377) |
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| toxicity | intrinsic health hazard of a substance (See page(s) 17) |
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| trace minerals | minerals in the diet that are usually required in micrograms (See page(s) 475) |
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| trans fats | fats that have been transformed by the addition of hydrogen to unsaturated vegetable oils (See page(s) 462) |
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| transgenic organisms | artificially created higher plants and animals that share the genes of another species (See page(s) 516) |
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| triglyceride | an ester of three fatty acid molecules and one glycerol molecule (See page(s) 458) |
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| triple bond | covalent linkage made up of three pairs of shared electrons (See page(s) 67) |
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| troposphere | region of the atmosphere that lies directly above the surface of the Earth (See page(s) 20) |
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| ultraviolet (UV) region | portion of the electromagnetic spectrum that includes wavelengths shorter than those of the visible color of violet (See page(s) 69) |
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| undernourishment | condition in which a person's daily caloric intake is insufficient to meet metabolic needs (See page(s) 454) |
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| unsaturated hydrocarbon | hydrocarbon molecule that contains one or more double bonds between the carbon atoms (See page(s) 459) |
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| vector | modified plasmid used to carry DNA back into the bacterial "host" (See page(s) 514) |
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| vitamin | organic molecule with a wide range of physiological functions. Although only small amounts are needed in the diet, vitamins are essential for good health, proper metabolic functioning, and disease prevention. (See page(s) 473) |
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| vitrification | process in which the spent fuel elements or other mixed waste from a nuclear reactor are encased in ceramic or glass (See page(s) 313) |
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| volatile | refers to a substance that readily passes into the vapor phase (See page(s) 36) |
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| volatile organic compounds (VOCs) | vapors of incompletely burned gasoline molecules or fragments of these molecules (See page(s) 37) |
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| voltage | difference in electrochemical potential between the two electrodes (See page(s) 333) |
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| volumetric flask | type of glassware that contains a precise amount of solution when filled to the mark on its neck (See page(s) 202) |
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| wavelength | distance between successive peaks of waves in the electromagnetic spectrum (See page(s) 68) |
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| wavenumbers | numbers often expressed in units of cm-1 and used on the x-axis of an infrared spectrum; inversely proportional to wavelength (See page(s) 116) |
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| work | form of energy describing movement against a restraining force. Mathematically, work is equal to the force multiplied by the distance over which the motion occurs. (See page(s) 152) |
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| X-ray diffraction | crystallography technique that generates a pattern of deflected X-rays passing through a crystal to reveal the nature of the crystal lattice (See page(s) 502) |