Terms
Anion
-
An ion with a net negative charge.
Atomic orbital
-
An orbital that is associated with only one particular atom. This is in
contrast to molecular orbitals, which are spread across a collection of
atoms.
Aufbau principle
-
German for "building up", a systematic procedure for determining the
electron configuration of any atom.
Cation
-
An ion with a net positive charge.
Degenerate orbitals
-
Orbitals with identical energies.
Electron affinity
-
The energy change in an atom when it gains an electron.
First ionization energy
-
The energy cost of removing one electron from an atom.
Hund's Rule
-
A rule which says that electrons prefer to go in separate orbitals when
choosing between orbitals of the same energy, in order to half-fill orbitals.
Ion
-
Any atom or molecule with a net charge.
Ionic bond
-
Bonding interaction that results from electrostatic attraction between
cations and anions.
Ionization energy
-
The energy it takes to remove an electron from an atom.
Isoelectronic
-
Description for two elemental species with the same electronic configuration.
Isotope
-
Atoms with the same number of protons (i.e. same atomic number) but a
different number of neutrons.
Octet rule
-
The cardinal rule of bonding. The octet rule states that atoms gain stability
when they have a full complement of 8 electrons in their valence shells.
Orbital
-
The region around an atom where an electron has a high probability of being
found.
Pauli Exclusion Principle
-
States that no two electrons in an atom or molecule can have the same set of four quantum numbers n, l, m, and s.
Second ionization energy
-
The energy cost of removing a second electron from an atom.
Shell
-
A group of subshells of similar energy levels. 2s and 2p subshells
occupy
the same shell.
Shielding
-
When the attraction from the nucleus felt by one electron is lessened or blocked
by intermediate electrons. Shielding can split degenerate orbitals.
For example, since s-orbital electrons shield for p-orbital electrons and
receive little shielding themselves, s-orbitals are usually of lower energy
level than p-orbitals of the same shell.
Splitting
-
The breaking of degenerate orbitals within a shell in multi-electron atoms.
Subshell
-
Orbitals in an atom with the same energy; orbitals of the same subshell are of
the same shape. p-orbitals are of the same subshell, while s-orbitals are of
a
separate subshell.
Uncertainty Principle
-
A tenet of quantum mechanics which says that the position and momentum of any
particle cannot both be known precisely at the same time.
Valence electron
-
The electrons in the outermost energy shell of an atom. The configuration of
these electrons determine the chemical properties of the element.
Valence shell
-
The highest energy shell in an atom. All interactions between atoms take
place through the electrons of the valence shell.
