Electron Structure The Quantum Number The electron’s “hood”

Electron Structure The Quantum Number The electron’s “hood” 3 dimensional address

Electron Structure The Quantum Number Attraction versus repulsion determines region, shape of region and spin of electron No electron can have the same 4 quantum numbers (Pauli Exclusion Principle)

Electron Structure The Quantum Number Principal energy level (n) 2 dimensional representation

Electron Structure The Quantum Number Principal energy level (n) Real pattern far different- both wave and particle L number (azimuthal) – shape and orbital

Electron Structure The Quantum Number Magnetic or m number Spatial orientation of the orbital within atom Starts with negative of l and goes to positive E.g. l=2, m=-2,-1,0,1,2

Electron Structure The Quantum Number Electron-spin quantum number AKA magnetic (m s ) number Illustration – Helium (He) atom Two electrons in one cloud Opposite “spin” or magnetic qualities + ½ (Arrow up) or -1/2 (arrow down)

Electron Structure The Quantum Number n=1, l=0, m=0 1s 2 s=+½,-½

Electron Structure This is the helium atom. It has 2 electrons. These are able to share the same s orbital because of opposite spins. The "2" in "1s 2 " means there are 2 electrons in that orbital. "s" orbitals can only hold 2 electrons, so that's as high as you will ever see it. The 1 in "1s 2 " means this is the s orbital belonging to the n=1 shell. n=1, l=0, m=0 1s 2, s=+½, -½

Electron Structure Pauli Exclusion Principle Each orbital can contain only one electron with each kind of spin If two electrons are in an orbital they must have different m s values

Electron Structure

Diagonal fill rule ◦ s levels fill first, p next, d after p and f last of all

Electron Structure Hund’s Rule

Electron Structure Aufbau principle

Electron Configuration & The Periodic Table

Orbital Notation

Longhand notation for Li: 1s 2 2s 1 Shorthand notation for Li: [He]2s 1 Be: [He]2s 2 B: [He]2s 2 2p 1 See table 4-5 p. 90 Hund’s rule example: C

Atomic Number & Mass Atomic Mass = sum of mass of protons + mass of neutrons

Atomic Number & Mass table/

The Periodic Table table/