Ions & Electron Configurations

VSEPR Shapes

VSEPR stands for:

Valance
Shell
Electron
Pair
Repulsion

Basically, this means that the electrons in the outermost shell repel each other and try to be as far apart as possible. When finding the shape then, you need to know how many bonds/electron pairs are around the center atom.

Orbital Energy Levels

Rules for filling orbitals... summarized:
Aufbau Principle: electrons fill from the lowest energy levels first.
*when filling in electrons, start at the bottom and work up.

Pauli Exclusion Principle: no two fermions can have the same quantum number.
*you can't have 2 electrons in the same place doing the same thing. Electrons can have spin up or spin down (this is 2 different quantum numbers). Therefore, if you have 2 electrons in 1 orbital, you must always have 1 up and 1 down. You may not have 2 ups or 2 downs. This is why we are limited to two electrons in each orbital.

Hunds rule: every orbital in a sublevel occupied by a single electron (going in the same spin direction) first before anything is doubly occupied.
*when given the choice, electrons choose to have their own orbital. Therefore, if there are 3 electrons in 3p, 1 will be in 3px, 1 in 3py, and 1 in 3pz.
Fill up each level with an up arrow on every line first before adding the second (down) arrow.

Orbital Filling Diagrams

Modern Atom Energy Levels

Orbital Energy Levels

Bohr vs. Modern Atom

NEW PICTURE!

Quantized -- electrons must be within a certain energy level. They CANNOT be in between. This is why you see a bright line spectrum not a full spectrum.

What are these orbitals??

Numbers (1, 2, 3) tell you the energy level (similar to Bohr's Orbit Levels)

Letters (s, p, d, f) tell you the shape of the energy level (there are more options than rings/orbits/circles!)