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smallest basic unit of matter


substance made of atoms of different elements that are bonded together in a set ratio

covalent bond

chemical bond formed when two atoms share one or more pairs of electrons


substance made of only one type of atom that cannot be broken down by chemical means


atom that has gained or lost one or more electron

ionic bond

chemical bond formed between oppositely charged ions


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


attration between molecules of the same substance


attractions between molecules of different substances


mixture that is consistant throughout: also called a homogeneous mixture


substance that dissolves in a solvent and is present at a lower concentration than the solvent


substance in which solutes dissolve and that is present in greatest concentration in a solution


substance that gives up a proton (H+) when dissolved in a solution


compound that takes up a proton (H+) when dissolved in a solution


measurement of acidity; related to the concentration of free hydrogen in a solution


molecular subunit of a polymer


large, carbon-based molecule formed by the smaller sub-units called monomers


molecule made of carbon of carbon, hydrogen, and oxygen; includes sugers and starches

fatty acid

hydrocarbon chain often bonded to glycerol in a lipid


polymer made up of amino acids linked by peptide bonds; folds into a particular structure depending on bonds between amino acids


nonpolar molecule made up of carbon, hydrogen, and oxygen; includes fats and oils

nucleic acid

polymer of nucleotides; the genetic material of organisms

chemical reaction

process by which substances turn into different substances through the making and breaking of chemical bonds


substance that is changed by a chemical reation


substance formed by a chemical reation

bond energy

amount of energy needed to break a bond between two particular atons; or the amount of energy released when a bond forms between two particular atoms


condition in which reactants and products of a chemical reaction are formed at the same rate

activation energy

the lowest amount of energy needed to start a chemical reaction


chemical reaction that yields a net release of energy in the form of heat


chemical reaction that requires a net input of energy

amino acid

molecule that makes up proteins; made of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur


substance that decreases activation energy and increases reaction rate in a chemical reaction


protein that catalyzes chemical reactions in organisms


reactant in a chemical reaction upon which an enzyme acts

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