1.4 Electron Configuration

electrons: particles that have little mass

• acts like waves

• have different frequencies and specific energy levels

• live in a cloud, not one particular spot

orbitals: regions around the nucleus where electrons are most likely to be found

• have specific shapes of electron cloud

• specific energy levels

• each shape has different orientations on the x, y, z plane

s-orbital: shaped like a sphere; one orbital orientation at each level

p-orbital: shaped like a bow tie; three orbital orientations at each level

d-orbital: shaped like a flower; five orbital orientations at each level

Pauli Exclusion Principle: only two electrons can occupy one orbital at a time; spin in opposite directions

Aufbau Principle: fill electrons from lowest energies first; smaller the principle quantum number, lower the energy level

Hund’s Rule: fill up each number level first before adding arrows to the next level; fill up boxes with upwards arrows before adding downwards

• arrows are one up and one down to show electrons spinning in opposite directions

when writing electron configuration, how arrangement of electrons listed in energy levels

• 1s²2s²3s

valence electrons: combination of highest energy level electrons