Electromagnetic Spectrum

Introduction

Fred Gross:

  • Four of his kids and his wife were poisoned.

  • He was cleared by Dr. Getler. And they also figured out the wife was the killer.

Light and the Bohr Model

Electronic structure of the atom came from the study of atomic spectra (spectroscopy). Scientists are looking at something called "line spectra."

Hydrogen spectra

Red, Orange

Blue, Violet

  • low frequency

  • low energy

  • high frequency

  • high energy

Energy of a light is proportional to its frequency -- discovered by Max Planck

Energy of a photon = frequency times Planck's constant

Photon

  • wave particle duality

  • it's what visible light is made up of

Bohr's Thoughts

Bohr thought that light was emitted from electrons moving between rings

If an electron encounters energy, electrons will go from a ground state to an excited state. It can also go back to its ground state, releasing energy --- and releasing visible light at the same time. The energy that it gains and loses is completely equal.

As N goes up, the more energy. But every single energy level has more to it than just lines. It's called an orbital.

Orbitals

Shape

Groups of

Electrons

S

sphere (electron cloud)

1

2

P

infinity sign in three orientations (X, Y, Z axis)

3

2

D

Complex shapes

5

2

F

Complex shapes

7

2

Energy level + orbital type

2 + P = 2P sublevel

N=1 = 1s

N=2 = 2s, 2p

N=3 = 3s, 3p, 3d

N=4 = 4s, 4p, 4d, 4f

(energy increases as you go from S ➝ F)

N

Sublevel

# of Orbitals

# of Electrons

Total Electrons

1

1S

1

2

2

2

2s

1

2

8

2p

3

6

3

3s

1

2

18

3p

3

6

3d

5

10

4

4s

1

2

32

4p

3

6

4d

5

10

4f

7

14

Instead of drawing an orbital, there's a few things

⬆⬇

S

P

d

f

Three Rules for Electrons

  1. Aufbau: Electrons will occupy the lowest available energy level.

  2. Pauli Exclusion Rule: If two electrons are in the same orbital, they have opposite spin

    1. Electrons are like little planets - constantly spinning

    2. Th at's why there's arrows pointing in opposite directions

  3. Hund's Rule: In a given sublevel, electrons will go into single orbitals before they double up. If they double up, they have opposite spin.

⬆

⬆

⬆

2P

if they double up, they need opposite spin

⬆⬇

⬆

⬆

2P

Stuff

The levels do overlap somewhat. 3f and 4s overlap.

Sublevels have slightly different energy.

Orbitals are centered on the nucleus.

Absorbtion spectrum - the atom can both emit a wavelength of light and absorb a wavelength of light.