Electron Configurations Chapter 5
Aufbau Principle Aufbau Principle: Electrons occupy the lowest energy orbital available
Aufbau Principle
Pauli Exclusion Principle Pauli Exclusion Principle: a maximum of two electrons may occupy a single atomic orbital, only if electrons have opposite spins.
Hund’s Rule Hund’s Rule: single electrons with the same spin must occupy each equal energy orbital before additional electrons can fill said orbitals.
Orbital Notation Box represents orbital. Each box is represented by its principle quantum number and sublevel associated with the orbital. Ex: C
Electron Configuration Notation Principle energy level, sublevel and superscript representing number of e- Ex: C C 1s 2 2s 2 2p 2
Nobel Gas Notation Uses Nobel gases to abbreviate electron configuration notation. Ex: Na Na 1s 2 2s 2 2p 6 3s 1 Can be abbreviated by using the previous noble gas Ne 1s 2 2s 2 2p 6 Na [Ne] 3s 1
Valence Electrons Valence Electrons: electrons in the outermost orbitals Chemical properties Main-group elements periodic table Ex: C
Electron-dot Structure Consists of atomic symbol, surrounded by dots representing the atom’s valence electrons. Ex: C
Exceptions Tendency for half filled orbital. Cr, Mo, Cu, Ag, Au 4s 1 3d 5, 5s 1 4d 5, 4s 1 3d 10, 5s 1 4d 10, 6s 1 4f 14 5d 10