Drill – 10/30 1. What is an orbital? Is an electron always within it? 2. What is the electron configuration for carbon (C)? 3. What is the electron configuration for gallium (Ga)?

Drill – 11/4 Write the electron configuration for Helium and identify the components of an electron configuration.

Drill – 11/8 Write the electron configurations for: 1.Tin (Sn) 2.Mercury (Hg)

Electron arrangement can be written in one of 3 ways: (1) Electron configuration (2) Orbital diagram (3) Noble-gas notation

Orbital Notation Arrows indicate electrons. Boxes, circles or lines represent each orbital

3 Rules for Electron Arrangement Aufbau Principle –Electrons always start filling at the lowest energy level. –Within each energy level, the s sublevel fills first, then p, then d, then f.

3 Rules for Electron Arrangement Pauli Exclusion Principle –A maximum of 2 electrons can be in one orbital. They must have opposite spins.

3 Rules for Electron Arrangement Hund’s Rule –Electrons fill each orbital in a sublevel before they start pairing up. p orbitals

Orbital Diagram 1s 2s 2p x 2p y 2p z Oxygen 8 electrons 1s 2 2s 2 2p 4

Exceptions to the Aufbau Principle Write the configurations for: Chromium (Cr) Copper (Cu)

Actual Configurations for Cr and Cu Cr: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 5 Cu: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 10 WHY??

Draw the correct orbital diagrams for each Cr and Cu.

WHY?? Having a half-filled or completely-filled d subshell gives the element a special stability d 4 & d 9 column will have exceptions every time!!

Noble Gas Notation Shorthand e - configuration –e - configurations of noble gases can be written using bracketed symbols ex: Ne 1s 2 2s 2 2p 6 = [Ne] –Write the bracketed symbol for the noble gas that precedes the element (period above it) and then continue filling orbitals with remaining electrons.

P151s 2 2s 2 2p 6 3s 2 3p 3 [Ne]3s 2 3p 3 Element# of e- e- configuration Nobel gas notation Ar181s 2 2s 2 2p 6 3s 2 3p 6 Ca201s 2 2s 2 2p 6 3s 2 3p 6 4s 2 [Ar]4s 2 Ne101s 2 2s 2 2p 6 [He]2s 2 2p 6 Br351s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 [Ar]4s 2 3d 10 4p 5 [Ne]3s 2 3p 6