BMS 507 Lecture Notes - Lecture 2: Covalent Bond, Relative Atomic Mass, Atomic Number
Document Summary
Atomic number determines the element: neutron neutral charge, electron negative charge. Determines reactivity of the atom based on # in valence shell: mass number: protons plus neutrons. Determines isotopes: atomic weight: exact mass of all particles, average of mass numbers of isotopes, measured in moles, chemical bonds. Form molecules or compounds: molecules: two or more elements joined, compounds: two or more different elements joined. Involves losing, sharing, and gaining of electrons in valence shells. Ionic: between cations and anions (donors and acceptors: donor loses electron and becomes cation, positive charge, acceptor gains electron and becomes anion, neg charge, attraction between opposite charges bonds them, ex: na+cl- (sodium chloride, table salt) Hydrogen: weak bonds with partial attractions: between adjacent molecules, not atoms. Involves slightly pos and neg portions of polar molecules: chemical reaction. Cannot start without help in cells: need activation energy and enzymes. Work: a change in mass or distance. Chemical energy: potential energy stored in chemical bonds: enzymes.
