Electron Configuration  the arrangement of electrons in an atom

Energy Level The principle quantum number designates the amount of energy Number 1 is closer to the nucleus and therefore has the least energy Numbers 2, 3, and 4, correspond to increasingly higher amounts of energy

General Information about Orbitals Orbital shapes vary s orbitals are spherical p orbitals are dumbbell shaped d orbitals are dumbbell and donut shaped f orbitals are just plain weird…don’t worry about them

More Information Only 2 electrons are allowed in each orbital s orbitals only hold 2 electrons p orbitals have 3 orientations and each can hold 2 electrons (6 total) d orbitals have 5 orientations and each can hold 2 electrons (10 total)

Aufbau Principle  electrons in an atom will occupy the lowest-energy orbitals available

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p

Steps to Write e - Configuration Decide how many electrons the atom has Starting with 1s, put 2 e - in like this: 1s 2 Then put 2 e - in the 2s orbital like this: 2s 2 6 e - can go in the 2p orbital like this: 2p 6 3s fills next with 2 e - and so on until you have no more electrons

Practice H He Li Be B C N 1s 1 1s 2 1s 2 2s 1 1s 2 2s 2 1s 2 2s 2 2p 1 1s 2 2s 2 2p 2 1s 2 2s 2 2p 3

More Practice O F Ne Na Mg Al Si 1s 2 2s 2 2p 4 1s 2 2s 2 2p 5 1s 2 2s 2 2p 6 1s 2 2s 2 2p 6 3s 1 1s 2 2s 2 2p 6 3s 2 1s 2 2s 2 2p 6 3s 2 3p 1 1s 2 2s 2 2p 6 3s 2 3p 2

Using the Periodic Table to Help The principle quantum number for s and p orbitals is the same as the row number Groups 1 and 2 fill the s orbitals (except He) Groups fill the p orbitals (except He) Groups 3-12 fill the d orbitals The principle quantum number for d is the row number minus 1