1. Electron Configuration and Periodic Trends

2. Evolution of Atomic Theory

3. Dalton’s Atomic Theory

4. Dalton’s Atomic Theory
did not explain how atoms break down into subatomic particles

5. J.J. Thompson

6. found the existence of electrons and created the plum pudding model
J.J. Thompson
found the existence of electrons and created the plum pudding model

7. Rutherford

8. Rutherford
discovered the nucleus and proposed the idea of a dense nucleus surrounded by electrons

9. Bohr

10. Bohr
proposed that electrons are arranged in orbits around the nucleus and that the electrons have a fixed energy so they can’t fall into the nucleus

11. Quantum Mechanical Model
The modern description of electrons in atoms proposed by Schrödinger

12. Quantum Mechanical Model
proposed that the
location and energy of an electron could be determined by the Schrödinger wave
equation

13. Quantum Mechanical Model

14. Quantum Mechanical Model
This model tells you that
the e is found 90% of the
time within a cloud

15. Quantum Mechanical Model

16. Quantum Mechanical Model and Atomic Orbitals
Principle Quantum Number
(n) designates energy levels
by n=1,2,3,4….as the
electrons move away from
the nucleus

17. Quantum Mechanical Model and Atomic Orbitals
Sublevels are found within
each energy level and they
are designated by s, p, d,
and f

18. Quantum Mechanical Model and Atomic Orbitals

19. Quantum Mechanical Model and Atomic Orbitals
Atomic orbitals make up
each sublevel

20. Quantum Mechanical Model and Atomic Orbitals
Each Atomic orbital
holds 2 electrons

21. Quantum Mechanical Model and Atomic Orbitals
Chart

22. Summary
Principle Quantum numbers always equal the number of sublevels within that energy level

23. Summary
The number of orbitals within each energy level is n2

24. Summary
The maximum number of electrons that can occupy each energy level is 2n2

25. Electron Configuration
The way electrons are arranged around the nucleus of an atom according to the quantum mechanical model
Represented by orbital notation

26. Electron Configuration
Guidelines:
1. Aufbau Principle
Electrons enter orbitals of lowest energy first

29. Electron Configuration
2. Pauli Exclusion Principle
An atomic orbital at most describes 2 electrons, and they must be of opposite spin

30. Electron Configuration
2. Pauli Exclusion Principle

31. Electron Configuration
3. Hund’s Rule
When electrons occupy orbitals of the same energy, one electron occupies each orbital until all electrons are of the same spin, then second electrons can be added

32. Electron Configuration
3. Hund’s Rule

33. Electron Configuration
Exceptions to the rules
Cu and Cr

34. Electron Configuration
Shorthand Notation
Energy level (n=1,2,3,…)
symbol for sublevel (s, p, d, f)
Superscript for electrons
Superscripts sum = total electrons

35. Electron Configuration

36. Electron Configuration
Noble Gas Notation
Previous noble gas symbol in brackets
Additional orbitals in shorthand

37. Electron Configuration
Noble Gas Notation