Introduction to Biochemistry Questions and Answers Graded A

atom The basic unit of matter. protons subatomic particle with positive charge found in the nucleus of an atom neutrons subatomic particle with no charge (neutral) found in the nucleus of an atom electrons subatomic particle with negative charge found in energy levels outside the nucleus valence electrons electrons found in the outermost energy level that are involved with bonding element pure substance, consisting of only 1 type of atom (like sodium) compound substance formed from the chemical combination of two or more elements in definite proportions isotope atoms of the same element with different numbers of neutrons ion charged atom formed when atom either loses electron(s) (and becomes + charged) or gains electron(s) becoming negatively charged ionic bonds involve a transfer of electrons and produces ions. Happens only between metals and nonmetals covalent bonds electrons are shared between atoms. Occurs between two nonmetals or in diatomic molecules. chemical reaction process by which atoms or groups of atoms in substances are reorganized into different substances chemical equation chemical formulas and symbols describe the substances in the reaction and arrows indicate the process of change reactants starting substances in a chemical reaction found on the left side of the (arrow) equation