Atomic (Hotels) Theory  Floors of the hotel are known as energy levels  The period corresponds to the floor. The number of the floor is called the Principle Quantum Number  Energy levels are divided into sublevels. These are the rooms of our atomic hotel. There are different types of rooms.  Atomic Orbital - Region of high probability of finding an electron  There are 4 types of rooms (orbitals). S, P, D, F rooms  s - Spherical p - dumbbell d- clover leaf f - too complex to describe.  s - superior p - preferred d- desirable f- fair  Floors of the hotel are known as energy levels  The period corresponds to the floor. The number of the floor is called the Principle Quantum Number  Energy levels are divided into sublevels. These are the rooms of our atomic hotel. There are different types of rooms.  Atomic Orbital - Region of high probability of finding an electron  There are 4 types of rooms (orbitals). S, P, D, F rooms  s - Spherical p - dumbbell d- clover leaf f - too complex to describe.  s - superior p - preferred d- desirable f- fair

Atomic (Hotels) Theory  Three Managers each with their own rule:  1. Aufbau principle  Rooms closest to the basement are checked out first  Electrons enter orbitals of lowest energy first  2. Pauli Exclusion Principle - no more than 2 per room  An atomic orbital contains a maximum of 2 electrons  Three Managers each with their own rule:  1. Aufbau principle  Rooms closest to the basement are checked out first  Electrons enter orbitals of lowest energy first  2. Pauli Exclusion Principle - no more than 2 per room  An atomic orbital contains a maximum of 2 electrons

Atomic (Hotels) Theory  3. Hund’s Rule  Best rooms are check out first  Similar rooms must have an occupant before pairing up as roommates  Roommates must have opposite spins to share a room  When electrons occupy orbitals of equal energy, one electron enters each orbital until all the orbitals contain one electron with parallel spins  3. Hund’s Rule  Best rooms are check out first  Similar rooms must have an occupant before pairing up as roommates  Roommates must have opposite spins to share a room  When electrons occupy orbitals of equal energy, one electron enters each orbital until all the orbitals contain one electron with parallel spins

S-orbitals of the 1st and 2nd energy levels.

P-orbital 2nd energy level