Electron Configuration

Atomic Structure and

Orbital (“electron cloud”)– Region in space where there is 90% probability of

finding an e-

Each orbital letter has a different shape.

“s” orbitalspherical shapedspherical shaped

“p” orbitalDumbbell shapedDumbbell shapedArranged x, y, z axes Arranged x, y, z axes

“d” orbitalclover shapedclover shaped

“f” orbital

f

• Orbitals combine to form a spherical shape.

2s

2pz2py

2px

Rules for e- configurations1. Aufbau principleAufbau principle: e- enter orbitals of lowest energy

level (Hogs are lazy, they don’t want to walk up stairs!)

2. Pauli exclusion principlePauli exclusion principle: an atomic orbital may describe at most 2 e-, e- in the same orbital will spin in opposite directions (They stink, so you can’t put more than two hogs in each room. & If hogs are in the same room they will face in opposite directions.)

3. Hund’s ruleHund’s rule: when e- occupy orbitals of = energy, 1 enters each orbital until all the orbitals contain 1 e- w/parallel spins (Hogs want to room by themselves, but they would rather room with another hog than walk up more stairs.)

Now you will relate the “Hog Hilton” to electron orbitals. Electron orbitals are modeled by the picture on the left and are grouped into principal energy levels.1. Compare their similarities and differences.2. To go between floors on the Hog Hilton did the hogs need to use energy? Would electrons need to use the energy to go between orbitals.

3d ___ ___ ___ ___ ___ n=3(4s ____) n=43p ___ ___ ___ n=33s ___ n=32p ___ ___ ___ n=22s ___ n=21s ___ n=1

6th floor ___5th floor ___ ___ ___4th floor ___3rd floor ___ ___ ___2nd floor ___1st floor ___

A. The principal quantum numbers, (n)• Electrons are in designated energy levels.

Organization of e- in the Quantum Mechanical model

The ground state- the lowest energy state of the atom

B. Within the energy level are sublevels, designated by letters.

Principal energy level

(n)

Number of

sublevels

Type of Orbital

1st energy level

1 sublevel “s” (1 orbital)

2nd 2 sublevels

“s” (1) & “p” (3 orbitals)

3rd 3 sublevels

“s”(1) , “p” (3) & “d” (5 orbitals)

4th 4 sublevels

“s”(1), “p”(3) , “d”(5), and “f” (7)

1s

2s2p

3p3s

4s3d

4p5s

4d5p

6s4f

5d6p7f

7s 7p6s 6p 6d 6f 6g5s 5p 5d 5f 5g4s 4p 4d 4f3s 3p 3d2s 2p1s

Filling in orbitals then writing the electron configuration

4p _ ↑↓ _ _ ↑_ _ ↑_3d _ ↑↓ _ _ ↑↓ _ _ ↑↓ _ _ ↑↓ _ _ ↑↓ _4s _ ↑↓ _3p _ ↑↓ _ _ ↑↓ _ _ ↑↓ _3s _ ↑↓ _2p _ ↑↓ _ _ ↑↓ _ _ ↑↓ _ 2s _ ↑↓ _

1s _↑↓_

What element is this? Count the electrons to find out…

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p4

Using the Noble Gases to write Shorthand• Write the noble gas that is in the previous row. • Use the symbol of the noble gas, put it in brackets, then write the

rest of the configuration.

When we write the e- config using Noble Gas notation…

It would be written [Ar] 4s2 3d10 4p4