Term | Definition |
Atom | The smallest unit of an element that maintains the chemical properties of that element |
Element | A substance that cannot be separated or broken down into simpler substances by chemical means; all atoms of an element have the same atomic number |
Compound | A substance made up of atoms of two or more different elements joined by chemical bonds |
Ion | An atom, radical, or molecule that has gained or lost one ore more electrons and has a negative or positive charge |
Ionic bond | The attractive force between oppositely charged ions, which form when electrons are transferred from one atom to another |
Covalent bond | A bond formed when atoms share one or more pairs of electrons |
Molecule | A group of atoms that are held together by chemical forces; a molecule is the smallest unit of matter that can exist by itself and retain all of a substance's chemical properties |
Hydrogen bond | The intermolecular force occurring when a hydrogen atom that is bonded to a highly electronegative atom of one molecule is attracted to two unshared electrons of another molecule |
Cohesion | The force that holds molecules of a single material together |
Adhesion | The attractive force between two bodies of different substances that are in contact with each other |
Solution | A homogenous mixture throughout which two ore more substances are uniformly dispersed |
Solvent | In a solution, the substance in which the solute dissolves |
Solute | In a solution, the substances that dissolves in the solvent |
Acid | Any compound that increases the number of hydronium ions when dissolved in water; acids turn blue litmus paper red and react with bases and some metals to form salts |
Base | Any compound that increases the number of hydroxide ions when dissolved in water; bases turn red litmus paper blue and react with acids to form salts |
pH | Measurement of acidity; related to free hydrogen ion concentration in solution |
Monomer | Molecular subunit of a polymer |
Polymer | A large molecule that is formed by more than five monomers, or small units |
Carbohydrate | A class of molecules that includes sugars, starches, and fiber; contains carbon, hydrogen, and oxygen |
Lipid | A fat molecule or a molecule that has similar properties; examples include oils, waxes, and steroids |
Fatty acid | Hydrocarbon chain often bonded to glycerol in a lipid |
Protein | An organic compound that is made of one or more chains of amino acids and that is a principal component of all cells |
Amino acid | A compound of a class of simple organic compounds that contain a carboxyl group and an amino group and that combine to form proteins |
Nucleic acid | An organic compound, either RNA or DNA, whose molecules are made up of one or two chains of nucleotides and carry genetic information |
Chemical reaction | Process by which substances change into different substances through the breaking and forming of chemical bonds |
Reactant | A substance or molecule that participates in a chemical reaction |
Product | A substance that forms in 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 | In biology, a state that exists when the concentration of a substance is the same throughout a space |
Activation energy | The minimum amount of energy required to start 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 | A molecule, either protein or RNA, that acts as a catalyst in biochemical reactions |
Substrate | A part, substance, or element that lies beneath and supports another part, substance, or element; the reactant in reactions catalyzed by enzymes |