(See related pages)
|
|
|
| Atom | the basic unit of an element that can undergo chemical change. (See page(s) 59; Sec. 2.1) |
| |
| |
| |
| Atomic number | the number of protons in the nucleus of an atom of an element. (See page(s) 59; Sec. 2.2) |
| |
| |
| |
| Atomic mass unit (u) | mass unit based on the mass of exactly 12 for  (See page(s) 59; Sec. 2.2) |
| |
| |
| |
| Avogadro’s number | 6.023 x 1023 atoms/mol; the number of atoms in one relative
gram-mole or mole of an element. (See page(s) 59; Sec. 2.2) |
| |
| |
| |
| Quantum mechanics | a branch of physics in which systems under investigation can
have only discrete allowed energy values that are separated by forbidden regions.
Ground state: the quantum state with the lowest energy. (See page(s) 59; Sec. 2.3) |
| |
| |
| |
| Photon | a particle of radiation with an associated wavelength and frequency. Also referred
to as a quantum of radiation. (See page(s) 59; Sec. 2.3) |
| |
| |
| |
| Ionization energy | the energy required to remove an electron from its ground state in an
atom to infinity. (See page(s) 59; Sec. 2.3) |
| |
| |
| |
| Heisenberg’s uncertainty principle | the statement that it is impossible to determine accurately
at the same time the position and momentum of a small particle such as an
electron. (See page(s) 59; Sec. 2.3) |
| |
| |
| |
| Quantum numbers | the set of four numbers necessary to characterize each electron in
an atom. These are the principal quantum number n, the orbital quantum number l, the
magnetic quantum number ml , and the spin quantum number ms. (See page(s) 59; Sec. 2.3) |
| |
| |
| |
| Atomic orbital | the region in space about the nucleus of an atom in which an electron
with a given set of quantum numbers is most likely to be found. An atomic orbital is
also associated with a certain energy level. (See page(s) 59; Sec. 2.3) |
| |
| |
| |
| Pauli exclusion principle | the statement that no two electrons can have the same four
quantum numbers. (See page(s) 59; Sec. 2.3) |
| |
| |
| |
| Electron shell | a group of electrons with the same principal quantum number n. (See page(s) 59; Sec. 2.3) |
| |
| |
| |
| Electron configuration | the distribution of all the electrons in an atom according to their
atomic orbitals. (See page(s) 59; Sec. 2.3) |
| |
| |
| |
| Anion | an ion with a negative charge. (See page(s) 59; Sec. 2.3) |
| |
| |
| |
| Cation | an ion with a positive charge. (See page(s) 59; Sec. 2.3) |
| |
| |
| |
| Ionic bond | a primary bond resulting from the electrostatic attraction of oppositely
charged ions. It is a nondirectional bond. An example of an ionically bonded material
is a NaCl crystal. (See page(s) 61; Sec. 2.5) |
| |
| |
| |
| Covalent bond | a primary bond resulting from the sharing of electrons. In most cases
the covalent bond involves the overlapping of half-filled orbitals of two atoms. It is a
directional bond. An example of a covalently bonded material is diamond. (See page(s) 61; Sec. 2.6) |
| |
| |
| |
| Hybrid orbital | an atomic orbital obtained when two or more nonequivalent orbitals
of an atom combine. The process of the rearrangement of the orbitals is called
hybridization. (See page(s) 61; Sec. 2.6) |
| |
| |
| |
| Valence electrons | electrons in the outermost shells that are most often involved in
bonding. (See page(s) 61; Sec. 2.7) |
| |
| |
| |
| Positive-ion core | an atom without its valence electrons. (See page(s) 61; Sec. 2.7) |
| |
| |
| |
| Metallic bond | a primary bond resulting from the sharing of delocalized outer electrons
in the form of an electron charge cloud by an aggregate of metal atoms. It is a nondirectional
bond. An example of a metallically bonded material is elemental sodium. (See page(s) 61; Sec. 2.7) |
| |
| |
| |
| Permanent dipole bond | a secondary bond created by the attraction of molecules that
have permanent dipoles. That is, each molecule has positive and negative charge centers
separated by a distance. (See page(s) 61; Sec. 2.8) |
| |
| |
| |
| Hydrogen bond | a special type of intermolecular permanent dipole attraction that
occurs between a hydrogen atom bonded to a highly electronegative element (F, O, N,
or Cl) and another atom of a highly electronegative element. (See page(s) 61; Sec. 2.8) |