Orbitals and Electron Configurations Section 6-5 to 6-8

Quantum Mechanics Incorporated both wave and particle behavior of electron Plucked guitar string Fundamental frequency Overtones Mathematical wave functions Square of wave function  probability map (orbital)

Orbital Shapes

Filling Orbitals Aufbau Principle – electrons first fill the lowest energy orbital available Hund’s Rule – electrons will only pair up when there are no longer any empty orbitals in the subshell

Electron Configuration For Aluminum: 1s2 2s2 2p6 3s2 3p1 Principal energy level (quantum) Number of electrons in sublevel Sublevel (orbital shape)

Orbital Diagram For Aluminum: 1s 2s 2px2py2pz 3s 3px3py3pz Boxes represent each orbital Electrons are shown using arrows

Core versus Valence Valence Electrons Electrons in the outer shell Determine chemical properties PT groups have same # valence e- Core Electrons All the inner electrons Noble gas configuration

Helpful tips Group number is the number of valence electrons for groups 1A to 8A Element’s period gives the number of the valence shell Number of valence electrons predict ionic charge

Quantum Mechanical Model Principal quantum number, n Angular momentum quantum number, l 0 – s 1 – p 2 – d 3 – f Magnetic quantum number, ml Ranges from –l to l

Electron Spin Spin magnetic quantum number, ms + 1 2 or - 1 2 Pauli Exclusion Principle orbital holds max of 2 electrons with opposite spins

Electron shell – all orbitals with same value of n Subshell – all orbitals with same value of n and l Shell has n subshells Subshell has 2 L + 1 orbitals Shell has n2 orbitals

Radial probability function – shows probability of finding the electron at certain distance from nucleus

PRACTICE Write the electron configuration for Cr U Write the orbital diagram for N F List the number of valence electrons for each element in 1 and 2 Identify the quantum numbers for the valence electrons for each element in 2