1. Models of the Atom
H.C.2A.3: Analyze and interpret absorption and emission spectra to support explanations that electrons have discrete energy levels.

2. Models of atoms Dalton JJ Thompson Ernest Rutherford Niels Bohr
Erwin Schrodinger

3. Bohr Model
Bohr suggested that an electron is found in only specific circular paths, or orbits, around the nucleus called ENERGY LEVELS.
According to this theory any atom could jump from one energy level to another by gaining or losing the right amount of energy
This theory was proven INCORRECT by Schrodinger’s Atom Model.

4. Quantum
A quantum of energy is the amount of energy required to move an electron from one energy level to the next energy level.
The amount of energy an electron gains of loses is NOT always the same.
Sometimes the amount of energy is more or less.
The Bohr model failed to explain why the amount of energy lost or gained would be different.

5. Quantum Mechanical model
Modern description of the atom is called the quantum mechanical model
Comes from Schrödinger's equation.
Does not involve an exact path around the nucleus

6. Energy levels Energy levels are represented by n = 1, 2, 3, 4, …
Each energy level has a MAXIMUM number of electrons
Energy Level (n)
Maximum number of electrons 1 2 8 3 18 4 32

7. Atomic Orbitals
Atomic Orbitals are thought of as a region of space in which there is a high probability of finding an electron.

8. Orbitals Orbitals also have a maximum number of electrons in each one.2 P 6 D 10 F 14

9. S orbital

10. P orbital

11. D orbital

12. F orbital

13. Animation

14. Electron Configuration
H.C.2A.3: Analyze and interpret absorption and emission spectra to support explanations that electrons have discrete energy levels.

15. SDPF Blocks

16. Electron configuration
The ways that electrons are arranged in various orbitals around the nuclei of atoms are called ELECTRON CONFIGURATION.
Three rules:
Aufbau Principle
Pauli Exclusion Principle
Hund’s Rule

17. Aufbau Principle
Electrons occupy the orbitals of the lowest energy level FIRST.

18. Pauli Exclusion Principle
An atomic orbital may describe at most two electrons.

19. Hund’s rule
Electrons occupy a suborbital singularly before any suborbital is occupied by a 2nd electron.

20. Orbital Notation
Carbon – 6 electrons C C C C C 1S 2S 2P

21. Electron COnfiguration
Carbon – 6 electrons
1S22S22P2

22. Orbital Notation
Neon – 10 electrons C C C C C 1S 2S 2P

23. Electron Configuration
Neon – 10 electrons
1S2 2S2 2P6

24. Practice – Write Electron configuration and Orbital notation
Lithium
Nitrogen
Chlorine
Selenium