CHM 2045C Key Terms Chapter
8
Atomic Electron
Configurations and Chemical Periodicity
Aufbau principle: the “building up” principle; as we move from element to element on the periodic table, the electrons are assigned to orbitals having the lowest energies possible, thus as we proceed, electrons are assigned to orbitals of increasingly higher energy
Diamagnetic: when a diamagnetic material is placed in a magnetic field, it is slightly repelled by the magnet; a diamagnetic material contains no unpaired electrons
Effective nuclear charge: the nuclear charge experienced by a particular electron in a multielectron atom, as modified by the presence of the other electrons
Electron affinity: the energy of a process in which an electron is acquired by an atom in the gas phase
Electron spin
magnetic quantum number (ms):
a quantum number which may have either a value
of +1/2 or -1/2; if an orbital contains one electron, the electron may have
either value of ms, but if the orbital contains two electrons, one
electron will have will have ms=+1/2, and the other electron will have ms + -1/2
Hund’s rule: in a given subshell each orbital is occupied
by one electron before pairing occurs
Ionization energy: the energy required to remove
an electron from an atom in the gas phase
Paramagnetic: when a paramagnetic material
is placed into a magnetic field, it is attracted to the magnet; a paramagnetic
material contains unpaired electrons
Pauli Exclusion Principle: no two
electrons in an atom can have the same set of four quantum numbers (n, l, ml,
and ms)
Valence electrons: the electrons in an atom that
go beyond the electron configuration of the previous noble gas