STATES OF AN ATOM Ground state: when an atom is at its lowest energy level Excited state when at atom gains energy

Orbitals An orbital is a three dimensional region around the nucleus where probably an e - is found There are four type of orbitals : s, p, d, and f Every single orbital can fit 2 electrons max. OrbitalShapeNumber of orbitals sSphere1 pdumbbells3 d“flower”5 f“weird”7

Valence electrons: are the electrons in the last level of energy. WE ALREADY KNOW THIS? Do we?

Principles and Rules For e config. Heisenberg uncertainty principle: States that it is impossible to know both the velocity and position of a particle at the same time Afbau Principle: States that each electron occupies the lowest energy orbital available. Hund’s rule: states that single electrons with the same spins must occupy each equal-energy orbital before they pair. Pauli exclusion principle: States that every single e must have different set of quantum numbers.

Orbitals s

Orbitals p

Orbitals d

ORBITAL DIAGRAM Use He = ↑↓ 1s Be = ↑↓ ↑↓ 1s 2s N = ↑↓ ↑↓ ↑ ↑ ↑ 1s 2s 2p x 2p y 2p z Fe ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑ ↑ ↑ ↑ _ 1s 2s 2p x 2p y 2p z 3s 3p x 3p y 3p z 4s 3d 3d 3d 3d 3d

DOT NOTATION Place dots around the element symbol indicating the number of electrons in the last level of energy.

1s 2 2s 2 2p 6 Last level of energy This particular atoms has 2 levels of energy 10 electron total electrons in the last level of energy 2 +6 What atom is this? How many dots are place around its symbol 11