1. Quantum Numbers n, l, m, and s – Used to describe an electron in an atom Probable location n – Principal Quantum Number – Represents main energy level of electron Maximum # of electrons in an energy level = 2n 2 Example: What is the maximum number of electrons that can be in the 5 th main energy level? – 2(5 2 ) – Electrons in 7 th energy level? Episode 304

2. Quantum Numbers l The 2 nd quantum number – Angular momentum quantum number Describes the orbital shape within an energy level Number of orbital shapes possible in an energy level = n http://www.youtube.com/watch?v=K- jNgq16jEY&list=PLD1C287B0E1484083&index=9&feature=plcp Episode 304

3. Orbital Shapes Designated s, p, d, and f Level 1: s Level 2: s, p Level 3: s, p, d Level 4: s, p, d, f Episode 304

4. How many electrons can each sublevel hold? s = 1 orbital x 2 e-/orbital = p = 3 orbitals x 2 e-/orbital = d = 5 orbitals x 2 e-/orbital = f = 7 orbitals x 2 e-/orbital = 2 e- 6 e- 10 e- 14 e- Energy Level n E sublevel Type of orbital # of orbitals# e- in orbital# e- = 2n 2 s 2 1 s p 1 1 36 2 2 2(1 2 ) = 2 2(2 2 ) = 8 Episode 304

5. Quantum Numbers m The 3 rd quantum number – Magnetic Quantum Number Describes the orientation of the orbital in space Episode 304

6. Quantum Numbers s The 4 th quantum number – Spin Quantum Number Describes the spin of the electron in orbital Ground state Lowest energy arrangement of electrons – Aufbau Principle http://www.youtube.com/watch?v=2ypC7rnFXLU&list=PLD1C287B0 E1484083&index=1&feature=plcp Episode 304

7. Diagonal Rule Examples: Hydrogen – 1 electron – 1s 1 Lithium – 3 electrons – 1s 2 2s 1 Nitrogen – 7 electrons – 1s 2 2s 2 2p 3 Episode 304

8. Electron Configurations – Describes the electron distribution within an atom Longhand electron configuration – Nitrogen 1s 2 2s 2 2p 3 Orbital Notation – Uses arrows to represent electrons Examples: – Hydrogen 1s 1 1s Episode 304

9. Nitrogen 1s 2 2s 2 2p 3 Hund’s Rule Orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron (spinning in opposite direction) Pauli Exclusion Principle No two electrons in the same atom can have the same set of 4 quantum numbers 2p2s1s Episode 304