1. Periodic Table Electron Configurations

2. Aufbau Principle – electrons occupy the orbitals of lowest energy first Hund’s Rule - electrons fill orbitals in the same energy level first with electrons spinning the same direction and then the other direction Valence electrons are the ones in the highest occupied energy level. N, P, As, Bi have the same outer energy level configurations.

4. The maximum number of electrons that can occupy one orbital is ____ 2 Give the symbol and name of the elements that correspond to these configurations of an atom. 1s 2 2s 2 2p 3 ____ ___________ N Nitrogen 1s 2 2s 2 2p 4 ____ ___________ O Oxygen 1s 2 2s 2 2p 6 3s 2 3p 1 ____ ___________ Al Aluminum

5. 1s 2 2s 2 2p 6 3s 2 3p 2 ____ ___________ Si Silicon 1s 2 2s 2 2p 6 3s 1 ____ ___________ Na Sodium 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 ____ ___________ K Potassium 1s 2 2s 2 2p 6 3s 2 3p 6 3d 2 4s 2 ____ ___________ Ti Titanium

6. How many valence electrons do the following elements have? oxygen ___________ 6 aluminum ___________ 3 sodium ___________ 1 barium ___________ 2

7. The next atomic orbital in the series 1s, 2s, 2p, 3s, 3p is ____ 4s The electron configuration for fluorine is ________ 1s 2 2s 2 2p 5 The correct electron configuration for silicon, atomic number 14 is __________ 1s 2 2s 2 2p 6 3s 2 3p 2 The configuration for the outermost (valence) energy level in Ca is _____ 4s 2

8. Which orbital configuration is the valence electron configuration for each of these elements? sulfur _____ s 2 p 4 germanium _____ s 2 p 2 beryllium _____ s 2 krypton _____ s 2 p 6 strontium _____ s 2

9. Give electron configurations for atoms of these elements Na _________________ 1s 2 2s 2 2p 6 3s 1 S _________________ 1s 2 2s 2 2p 6 3s 2 3p 4 Mg _________________ 1s 2 2s 2 2p 6 3s 2 Ne _________________ 1s 2 2s 2 2p 6

10. K _________________ 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 selenium _________________ 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 4 vanadium _________________ 1s 2 2s 2 2p 6 3s 2 3p 6 3d 3 4s 1 nickel _________________ 1s 2 2s 2 2p 6 3s 2 3p 6 3d 8 4s 2 calcium _________________ 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2