1. Where exactly are the electrons? It’s all a little cloudy!

2. The Electron Cloud.

3. A closer look at the Electron Cloud

4. ELECTRONIC CONFIGURATION
With electronic configuration elements are represented numerically by the number of electrons in their shells and number of shells. For example;
Nitrogen
configuration = 2 , 5 7
2 in 1st shell
5 in 2nd shell N
= 7 14

5. ELECTRONIC CONFIGURATION
Write the electronic configuration for the following elements; 20 11 8 Na O Ca a) b) c) 16 23 40
2,8,8,2
2,8,1
2,6 17 14 5 Cl Si B d) e) f) 11 35 28
2,8,7
2,8,4
2,3

6. Energy level
An energy level is a region of fixed energy, within an atom, than an electron occupies.
Energy level 1 (n= 1) can hold up to 2 electrons
Energy level 2 (n= 2) can hold up to 8 electrons
Energy level 3 (n= 3) can hold up to 18 electrons
Energy level 4 (n= 4) can hold up to 32 electrons

7. Orbitals (Region in space, around an atom where there is a high probability of finding an electron)
S – Orbitals
P - Orbitals

8. Sub-levels ( Group of orbital in the same energy level)

9. A closer look at the atom (all ideas incorporated)

10. The journey of ideas
Electron cloud ~ Electrons in a cloud around the nucleus of the atom
Energy level ~ electrons in fixed energy levels around nucleus of atom.
Energy level, sublevels and orbitals ~ a more detailed explanation of the position or the electrons in an atom

11. Showing the location of the electrons

12. Energy level diagrams
Sub-level
orbital
Main energy level

13. Filling energy levels, sublevels and orbitals
The Aufbau Principle
Hund’s Rule
Pauli’s Exclusion Principle

14. The Aufbau Principle
Electrons will occupy the lowest energy level available, before filling the next energy level.
Energy level 1 will be filled before energy level 2)

15. Hunds Rule
Electrons will occupy orbitals of equal energy level on their own before they will occupy them in pairs.

16. Paulis Exclusion Principle
Only two electrons can fill an orbital, and these orbitals must be in opposite spin to each other.

17. Filling energy levels, sub levels and orbitals
Name of Element = No. of electrons =