1. Electron Configurations
Notation for Electrons

2. Where Are the Electrons?
Rutherford said they were outside the nucleus
But how are the electrons organized in relationship to the nucleus
The electrons are extremely important as they determine how an element reacts
The organization of the electrons determines an elements physical and chemical properties

3. Niels Bohr a review
Compares electrons orbiting the nucleus of an atom to planets orbiting around the sun.
Electrons occupy distinct orbitals.
Orbitals have certain energies and distances from the nucleus.

4. Erwin Schrodinger a review
Regions where electrons are most likely found are called “electron clouds”.
Different types of orbitals have different shapes and different levels of energy.
Although difficult to understand, the results were spectacular!
This new model of the atom explained the physical properties of atoms, and the Periodic Table, perfectly.

5. Principle Quantum Level (n)
The quantum level is the energy level of the electron (shell); the 1st shell, 2nd shell
Energy increases as you move out
Each quantum level has sub levels of different shapes

6. Sublevels
The number of sublevels is equal to the quantum level or energy level
The first level energy level has one sublevel,
The second energy level has two sublevels
The third energy level has three sublevels

7. Sublevels Each orbital type holds a different number of electrons
S shape has1 orbital for a total of total of 2 electrons
P shape has 3 orbitals for a total of 6 electrons
D shape has 5 orbitals for a total of 10 electrons
F shape has 7 orbitals for a total of 14 electrons

8. Principle energy level (n) Type of shape Number of orbitals per type
Orbitals and Electron Capacity of the First Four Principle Energy Levels
Principle energy level (n)
Type of shape
Number of orbitals per type
Number of orbitals per level(n2)
Maximum number of electrons (2n2) 1 s 2 4 8 p 3 9 18 d 5 16 32

10. Summary First level of organization Second level of organization
Energy level numbered 1-7
Second level of organization
Energy levels broken into shapes
The number of orbital is equal energy level
Each shape has different number of orbitals
Each orbital holds 2 electrons
Electrons are placed in the lowest energy levels first

11. Putting the Electrons in Place
Electrons are put in the lowest energy levels first
The order is 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 5d, 4f,
Note that the s orbitals in the next energy are filled before the d level
Maximum electrons in each orbital are:
S – 2 electrons
P – 6 electrons
D – 10 electrons
F – 14 electrons

12. This chart gives the specific order that the energy levels are filled

13. Another Way to View the Order Each Dash Is an Orbital Which Can Hold 2 Electrons
2p__ __ __
3s__
3p__ __ __
4s __
3d __ __ __ __ __
4p __ __ __
5s __
4d __ __ __ __ __
5p __ __ __

14. Lets Try One Oxygen 8 Electrons
1 s 2 electrons
2 s 2 electrons
2 p 4 electrons
The electron configuration can be written as 1s22s22p4

15. Lets Try Another Ca 20 Electrons
1s 2 electrons
2s 2 electrons
2p 6 electrons
3s 2 electrons
3p 6 electrons
4s 2 electrons
1s22s22p63s23p64s2