1. !Electrons in Atoms
Chapter 13.1 and 13.2

2. Atomic Models
!Atomic models help explain the nature of elements—part of atomic theory
We can not see atoms, so how do we know they exist?

3. !Scanning Tunneling Microscope
!Can “see” atoms! Can even be used to rearrange individual atoms!

4. !Thompson’s Plum Pudding Model
Thompson imagined a positively charged ball of “pudding” with electrons (which he discovered) as the “plums” inside

5. Niels Bohr’s Model
1913: !Bohr imagined electrons follow circular orbits around the nucleus, like a solar system

6. Energy Levels
!The energy level of an electron is the region around the nucleus where the electron is moving

7. !Energy Levels are Fixed
!Energy levels are like rungs on a ladder
!Electrons exist on rungs
!Electrons can jump between rungs
!Electrons can’t exist between rungs

8. It takes energy to jump between energy levels
!Quantum: The amount of energy required to move from one energy level to another
Part of the Quantum Theory

9. Neils Bohr
"If quantum mechanics hasn't profoundly shocked you, you haven't understood it yet."

10. Light and Atomic Spectra
!Spectrum: a series of energies (like light) arranged according to wavelength, or frequency

11. !Atomic Emission Spectrum
!Every element (vapor) emits light when it is excited by the passage of electric discharge.

12. Atomic Emission Spectrum
!Passing this light through a prism creates a spectrum, different for every element.
!Each line represents one exact amount of energy

13. More on Quantum Theory:
Subatomic particles don’t follow the rules of classical physics
Gravity doesn’t apply!
Time doesn’t apply!
Can move without occupying space!
Superposition—can’t locate position!
Order of operations don’t always apply!

14. Neils Bohr
"If quantum mechanics hasn't profoundly shocked you, you haven't understood it yet."

16. The Quantum Mechanical Model
Erwin Schrodinger, in 1926, used quantum theories to solve a mathematical equation concerning the location and energy of an electron.
(But not both at once)

19. !Electron Orbitals—Quantum Theory
!The area where an electron is likely to be found. (90% chance)
!An orbital can contain two electrons.

21. Energy levels and orbitals
!Types of orbitals
!s orbital = sphere shaped (1 type)
!p orbitals = dumbell shaped (3 types)
!d orbitals = clover shaped (5 types)

23. Electron Configurations
High energy = unstable, higher energy levels, further away from nucleus
Low energy = stable
Three major rules tell you how to find where electrons will be:

24. !Rule 1: Aufbau Principle
!Electrons enter orbitals of lowest energy first.

25. !Rule 2: Pauli Exclusion Principle
!An atomic orbital is one or two electrons
To be in the same orbital, two electrons must be “opposite”

26. !Rule 3: Hund’s Rule
!Electrons in the same energy level must enter each orbital until all the orbitals contain one electron with parallel spins.

28. !Electron Cloud
!All the electrons in all the orbitals.