1.4 Quantum Mechanical Model of Atoms

Quantum Mechanical Model

• Electrons do not travel in different orbits but are localized in orbitals

• Orbitals are regions of space around the nucleus defined by the probability of finding an electron in that region of space

Heisenberg Uncertainty Principle

• Impossible to know both an electron’s position and its momentum exactly at the same time

Principal Quantum Number

• N

• Describes the average energy of a shell

Azimuthal Quantum Number

• L

• Describes the subshells within a given principle energy level (s, p, d, f)

Magnetic Quantum Number

• Mi

• Specifies the particular orbital within a subshell where an electron is likely to be found at a given moment in time

Spin Quantum Number

• Ms

• Indicates the spin orientation (+1/2 or -1/2) of an electron in an orbital

Electron Configuration

• Electrons fill the principal energy levels and subshells according to increasing energy, determined by n+L rule

Hund’s Rule

• Subshells with multiple orbitals (p, d, f) fill electrons so that every orbital in a subshell will get one electron before any of them get a second

Paramagnetic

• Unpaired electrons that align with magnetic fields, attracting material to a magnet

Diamagnetic

• Paired electrons that cannot be easily realigned and repelled by magnets

Valence Electrons

• Those electrons in the outermost shell available for interaction (bonding) with other atoms

• For the representative elements (Groups 1, 2, 13-18) valence electrons are in s and/or p orbitals

• For transition elements, valence electrons are found in s, d, or f orbitals