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Freshman Biology - Chapter 2 - The Chemistry of Life


the basic unit of matter


the center of an atom, which contains the protons and neutrons; in cells, structure that contains the cell's genetic material in the form of DNA


negatively charged particle; located in the space surrounding the nucleus


pure substance that consists entirely of one type of atom


on of several forms of a single element, which contains the same number of protons but different numbers of neutrons


substance formed by the chemical combination of two or more elements in definite proportions

ionic bond

chemical bond formed when one or more electrons are transferred from one atom to another


atom that has a positive or negative charge

covalent bond

type of bond between atoms in which the electrons are shared


smallest unit of most compounds that displays all the properties of that compound

van der Waals forces

slight attraction that develops between oppositely charged regions of nearby molecules

hydrogen bond

weak attraction between a hydrogen atom and another atom


attraction between molecules of the same substance


force of attraction between different kinds of molecules


material composed of two or more elements or compounds that are physically mixed together but not chemically combined


type of mixture in which all the components are evenly distributed


substance that is dissolved in a solution


dissolving substance in a solution


mixture of water and nondissolved material

pH scale

scale with values from 0 to 14; used to measure the concentration of H+ ions in a solution; a pH of 0 to 7 is acidic; a p H of 7 is neutral, and a pH of 7 to 14 is basic


compound that forms hydrogen ions (H+) in solution; a solution with a pH of less than 7 (44)


compound that produces hydroxide ions (OH++) in solution; solution with a pH or more than 7


compound that prevents sharp, sudden changes in pH


small chemical unit that makes up a polymer


molecules composed of many monomers; makes up macromolecules


compound made up of carbon, hydrogen, and oxygen atoms; type of nutrient that is the major source of energy for the body


simple sugar molecule


macromolecule made mostly from carbon and hydrogen atoms; includes fats, oils, and waxes

nucleic acid

macromolecules containing hydrogen, oxygen, nitrogen, carbon, and phosphorus


subunit of which nucleic acids are composed; made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base


macromolecule that contains carbon, hydrogen, oxygen, and nitrogen; needed by the body for growth and repair

amino acid

compound with an amino group on one end and a carboxyl group on the other end

chemical reaction

process that changes, or transforms, one set of chemicals into another set of chemicals


elements or compounds that enter into a chemical reaction


elements or compounds produced by a chemical reaction

activation energy

energy that is needed to get a reaction started


substance that speeds up the rate of a chemical reaction


protein catalyst that speeds up the rate of specific biological reactions


reactant of an enzyme-catalyzed reaction

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