electron configurations pre ap

Electron Configurations

Electron Configurations

• Electron Configurations – the way electrons are arranged (placed) around the nucleusnucleus.

• Guiding Principle: electrons are arranged in a way that gives the lowest lowest energy to the atom. (low energy = high stability)

Rules for Electron Configurations

• Aufbau Principle – lowest lowest energy levels fill first.• Pauli Exclusion Principle – no two electrons in an atom

can be at the samesame place at the samesame time. All atomic orbitals can only hold 2 electrons maximum & they have to be spinning opposite directions.

• Hund’s Rule – Don’t pair until you have to.Don’t pair until you have to. When electrons can go into orbitals of equal energy (ex.3 types of p orbitals) one electron enters each orbital until each has one electron. They all spin the same direction until they pair up.

• Each orbital corresponds to a specific sectionsection on the periodic table.

How orbitals align on the Periodic Table

Drawing Orbital Box Diagrams

You try a few!

• Nitrogen

• Chlorine

1s2 2s2 2p3

3s2 3p51s2 2s2 2p6

Write the electron configurations for the following elements:

• Hydrogen• Helium• Lithium• Beryllium• Boron• Fluorine• Sodium• Phosphorus

1s1s11

1s1s22

1s1s222s2s11

1s1s222s2s22

1s1s222s2s222p2p11

1s1s222s2s222p2p55

1s1s222s2s222p2p663s3s11

1s1s222s2s222p2p663s3s223p3p33

Using the “d” orbitals

• The transition metals use the “d” orbitals to denote their electron configurations.

• “d” orbitals have a higherhigher energy level than “s” orbitals with a larger number. Therefore, the “s” orbital will fill before the “d” orbital.

• There are exceptionsexceptions to the rule within the transition elements.

Examples

• Scandium

1s1s222s2s222p2p663s3s223p3p664s4s223d3d11

• Titanium

1s1s222s2s222p2p663s3s223p3p664s4s223d3d22

• Vanadium

1s1s222s2s222p2p663s3s223p3p664s4s223d3d33

You try a few!

• Iron

• Nickel

• Bromine

1s1s222s2s222p2p663s3s223p3p664s4s223d3d66

1s1s222s2s222p2p663s3s223p3p664s4s223d3d88

1s1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p55

Using the “Core” to shorten things up:

• Instead of writing the entire electron configuration, you can use the “core”“core” of the last noble gas.

• Example: Phosphorous

Regular - 1s1s222s2s222p2p663s3s223p3p33

Core - [Ne] 3s3s223p3p33

You try!

Chlorine

Barium

Iodine

[Ne] 3s[Ne] 3s223p3p55

[Xe] 6s[Xe] 6s22

[Kr] 5s[Kr] 5s224d4d10105p5p55

What is the most common college mascot in the NCAA?

Bulldogs – shared by 13 teams

2nd – Tigers

3rd – Bears

4th- Wildcats