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