Electron Configuration Where are the electrons??? Each element has a unique e- config.

Main energy level (like floors of a building)- # also indicates the number of sublevels Sublevel (like rooms in a building) – s, p, d, f Orbitals (like closets) – Can hold 2 electrons - Sublevels contain orbitals s sublevel - 1 orbital

p sublevel - 3 orbitals

d sublevel - 5 orbitals

f sublevel - 7 orbitals (Fill out chart)

Total # of electrons in energy level Energy Level (n) E sublevel # of Orbitals # of e- in each sublevel Total # of electrons in energy level 1 s 2 p 3 6 8 d 5 10 18 4 f 7 14 32

Aufbau Principle E- occupy the lowest energy level first

Pauli Exclusion Principle Two e- with opposite spin can occupy one orbital.

Hund’s Rule Electrons are spread out in the same sublevel before doubling.

Other info **Valence Electrons – all the e- in the highest main energy level **Inner-shell electrons – all the e- except valence electrons **Complete Octet – 8 valence e-, stable atom (Noble Gases)

Orbital Notation *Orbital (box or line) *Electron (arrow) *Energy level – numbers *Sublevel - letters

Orbital Notation ___ ___ ___ ___ ___ ___ ___ ___ ___ 1s 2s 2 p 3s 3p Electron Orbital Energy Level Sublevel

Electron Configuration Notation 1s2 2s2 2p6 Number of e- in orbital Energy level Sublevel

Examples: O – Si – (valence e-?)

1 2 18 13 14 15 16 17

Noble Gas Configuration Noble Gas – Group 18 *Has 8 valence electrons (except He) *Has a complete octet - unreactive Use the Noble Gas on the previous row to substitute for part of the electron configuration

Lewis Dot Diagrams Dots represent valence electrons Valence electrons are in “s” and “p” sublevels only, called the “main group” elements. Group 18 has 8 valence electrons (except for He) Examples:

Excitation of Electrons Electrons absorb energy Electrons jump from the ground state to a higher energy level Unstable electron in excited state falls back down to ground state. The electron releases a photon. (Photon is a “packet” of a specific amount of energy that we see as light).

Four ways to excite electrons: Heat Electricity Chemiluminescence UV light