| A | B |
|---|
| atom | smallest basic unit of matter |
| element | substance made of only one type of atom that cannot be broken down by chemical means |
| compound | substance made of atoms of different elements that are bonded together in a particular ratio |
| ion | atom that has gained or lost one of more electrons |
| ionic bond | chemical bond formed through the electrical force between oppositely charged ions |
| covalent bond | chemical bond formed when two atoms share one or more pairs of electrons |
| molecule | two or more atoms held together by covalent bonds; not necessarily a compound |
| hydrogen bond | attraction between a slightly positive hydrogen atom and a slightly negative atom |
| cohesion | attraction between molecules of the same substance |
| adhesion | attraction between molecules of different substances |
| solution | mixture that is consistent throughout; also called a homogeneous mixture |
| solvent | substance in which solutes dissolve and that is present in greatest concentration in a solution |
| solute | substance that dissolves in a solvent and is present at a lower concentration than the solvent |
| acid | compound that donates a proton (H+) when dissolved in a solution |
| base | compound that accepts a proton (H+) when dissolved in a solution |
| pH | measurement of acidity; related to free hydrogen ion concentration in a solution |
| monomer | molecular subunit of a polymer |
| polymer | large, carbon-based molecule formed by monomers |
| carbohydrate | molecule composed of carbon, hydrogen, and oxygen; includes sugars and starches |
| lipid | nonpolar molecule composed of carbon, hydrogen, and oxygen; includes fats and oils |
| fatty acid | hydrocarbon chain often bonded to glycerol in a lipid |
| protein | polymer composed of amino acids linked by peptide bonds; folds into a particular structure depending on bonds between amino acids |
| amino acid | molecule that makes up proteins; composed of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur |
| nucleic acid | polymer of nucleotides; the genetic material of organisms |
| chemical reaction | process by which substances change into different substances through the breaking and forming of chemical bonds |
| reactant | substance that is changed by a chemical reaction |
| product | substance formed by a chemical reaction |
| bond energy | amount of energy needed to break a bond between two particular atoms; or the amount of energy released when a bond forms between two particular atoms |
| equilibrium | condition in which reactants and products of a chemical reaction are formed at the same rate |
| activation energy | energy input necessary to initiate a chemical reaction |
| exothermic | chemical reaction that yields a net release of energy in the form of heat |
| endothermic | chemical reaction that requires a net input of energy |
| catalyst | substance that decreases activation energy and increases reaction rate in a chemical reaction |
| enzyme | protein that catalyzes chemical reactions for organisms |
| substrate | reactant in a chemical reaction upon which an enzyme acts |
