Term | Definition |
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 or 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 solution. |
pH | Measurement of acidity; related to free hydrogen ion concentration in 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 time. |
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. |