Unit 4 Notes: Electron Configurations

(1) Shells vs. Orbitals• Shell = Large area you are most

likely to find electrons in an atom.

• Orbital = Weird shaped plane within a shell, holding specific quantities of electrons.

(2) Types of Orbitals• s = can only ever hold 2 electrons

• p = can only ever hold 6 electrons

• d = can only ever hold 10 electrons

• f = can only ever hold 14 electrons

(3) Filling the Orbitals• Fill in order of:

s p d f

• Some shells, only have certain orbitals…LOOK AT ORBITAL CHEAT-SHEET

(4) What is an Electron Configuration?

• Abbreviated way of showing how electrons are distributed throughout an atom.

• Unique for EACH element!

(5) Writing Electron Configurations:

1. Always start with 1s

2. Exponent (Superscript) Numbers:They tell you the number of electrons in that orbital.

3. Coefficient Numbers (Numbers in front of orbitals):They tell you which shell we are in.

4. Example: Aluminum1s2 2s2 2p6 3s2 3p1

(6) Shorter Electron Configurations:

1. Write the Noble Gas that was right before it. Example: [Ne]

2. Then write the rest out like you normally would.

3. Example: Aluminum[Ne] 3s2 3p1

(7) Write the Electron Configuration for:

(SULFUR)

(8) Write the Electron Configuration for:

(LITHIUM)

(9) Write the Electron Configuration for:

(GALIUM)