Orbital Diagrams and - PowerPoint Presentation

Slide1

Orbital Diagrams and Electron Configurations

Vocabulary:Electron configurationAufbau PrinciplePauli Exclusion Principleelectron spinHund’s RuleOrbital diagram

Paul Klee,

Greeting

, 1922. American.Slide2

SubshellsWe’ve talked about the different orbitals (subshells) that give us the probable location of electrons of various energy states. But how do we know which subshell any one electron will occupy? Should it go in an s, p, d, or f orbital? And which energy level?

Luckily there are 3 rules to guide our understanding of the position of ground state electrons in an atom.Slide3

The rules:

1. The Aufbau Principle: Electrons fill orbitals with the lowest energy first. “Aufbau” is German for “Building up.”Slide4

The rules:

To follow the Aufbau principle, you must know the order of orbital energy. The following chart will help you with this order:1st Energy level 1sThere is only an s orbital on the 1st energy level.Slide5

The rules:

To follow the Aufbau principle, you must know the order of orbital energy. The following chart will help you with this order:1st Energy level 1s2nd Energy level 2s 2pThere are only s and p orbitals on the 2nd energy level.Slide6

The rules:

To follow the Aufbau principle, you must know the order of orbital energy. The following chart will help you with this order:1st Energy level 1s2nd Energy level 2s 2p3rd Energy level 3s 3p 3dThere are only s, p, and d orbitals on the 3rd energy level.Slide7

The rules:

To follow the Aufbau principle, you must know the order of orbital energy. The following chart will help you with this order:1st Energy level 1s2nd Energy level 2s 2p3rd Energy level 3s 3p 3d4th Energy level 4s 4p 4d 4f

The 4th, 5th, 6th, and 7th energy levels contain all 4 types of orbitals

(although you will not ever use the 6f , 7d, or 7f orbitals.)5th Energy level 5s 5p 5d 5f

6th Energy level 6s 6p 6d 6f7

th Energy level 7s 7p 7d 7fSlide8

The rules:

Sadly, the order of increasing energy does not follow left to right, top to bottom on this chart. Instead you need to add some arrows to help with the order.1st Energy level 1s2nd Energy level 2s 2p3rd Energy level 3s 3p 3d4th Energy level 4s 4p 4d 4f

5th Energy level 5s 5p 5d 5f6

th Energy level 6s 6p 6d 6f7th Energy level 7s 7p 7

d 7f

Start hereSlide9

The rules

So following the chart, the order of the orbitals in increasing energy is:1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, and 7p.Slide10

2. The Pauli Exclusion Principle: Only two electrons can occupy each orbital, but each must have opposite spin.

The rulesWolfgang Pauli(Austria):Nobel prize in Physics, 1945Slide11

Spin refers to a magnetic field created by an electron. Two electrons in the same orbital must have opposite spin meaning they have opposite magnetic field orientation. We’ll represent this using an up arrow for an electron with + spin and a down arrow for an electron with – spin.

 = electron with positive spin  = electron with negative spinThe rulesSlide12

3. Hund’s Rule: If two or more orbitals of equal energy are available, electrons will occupy them singly before filling them in pairs.

The rulesFriedrich Hund (German)Slide13

So for example, if you are placing 4 electrons into the 2p orbitals, they would fill in the following order due to Hund’s Rule:

The rules2p __ __ __2p __ __ __ correct incorrectSlide14

So let’s see the rules in action!

Draw the orbital diagram for carbon (6 electrons). 1s ___Rule 1: Use chart to f

ill lowest energy orbitals first.

Rule 2: Two electrons in each orbital with opposite spin.

2

s ___

2

p ___ ___ ___

3 lines because there are 3 types of p-

orbitals

.

Rule 3: Fill

orbitals

of equal energy 1 at a time and then pair up.Slide15

So let’s see the rules in action!

Draw the orbital diagram for carbon (6 electrons). 1s ___Rule 1: Use chart to f

ill lowest energy orbitals first.

Rule 2: Two electrons in each orbital with opposite spin.

2

s ___

2

p ___ ___ ___The six arrows represent the positions of the six electrons in a ground state carbon atom.

Rule 3: Fill

orbitals

of equal energy 1 at a time and then pair up.Slide16

So let’s see the rules in action!

Draw the orbital diagram for carbon (6 electrons). 1s ___Rule 1: Use chart to f

ill lowest energy orbitals first.

Rule 2: Two electrons in each orbital with opposite spin.

2

s ___

2

p ___ ___ ___We can show this orbital diagram in a more abbreviated form called an electron configuration.

Rule 3: Fill

orbitals

of equal energy 1 at a time and then pair up.Slide17

So let’s see the rules in action!

Draw the orbital diagram for carbon (6 electrons). 1s ___Rule 1: Use chart to f

ill lowest energy orbitals first.

Rule 2: Two electrons in each orbital with opposite spin.

2

s ___

2

p ___ ___ ___1s2

Rule 3: Fill

orbitals

of equal energy 1 at a time and then pair up.

2

s

2

2

p

2

This is the electron configuration for carbon.Slide18

1s __

2s __ 2p __ __ __3s __ 3p __ __ __ 3d __ __ __ __ __4s __ 4p __ __ __ 4d __ __ __ __ __Let’s try another one.Draw the orbital diagram and write the electron configuration for iron: 26 electrons.

Electron Configuration:1s22s22p63s2

3p64s23d6Slide19

Try one on your own.

Draw the orbital diagram and write the electron configuration for rubidium: 37 electrons.Slide20

1s __

2s __ 2p __ __ __3s __ 3p __ __ __ 3d __ __ __ __ __4s __ 4p __ __ __ 4d __ __ __ __ __5s __Try one on your own.Draw the orbital diagram and write the electron configuration for rubidium: 37 electrons.

Electron Configuration:1s22s22p63s

23p64s23d104p65s1