Noble Gases Argon :1s2 2s2 2p6 3s2 3p6 Potassium: 1s2 2s2 2p6 3s2 3p6 4s1 Simplified electron configuration for Argon: [Ar] Simplified electron configuration for Potassium: [Ar] 4s1 Noble Gas Simplification

Noble Gas Simplification Take the last noble gas before the element of interest Put the noble noble gas we put into the brackets Finish the electron configuration for the element Example: Aluminum: [Ne]3s23p1  Calcium: [Ar]4s2

Noble Gas Simplification This notation for writing electron configurations helps us to highlight 2 different types of electrons in the atom 1. Electrons in the brackets are called core electrons These electrons do not participate in chemical reactions 2. The electrons written after the [noble gas] are called valence electrons Valence electrons are those electrons in the highest principal energy level These electrons are important because they are the ones that are gained, lost or shared in chemical reactions.

Noble Gas Simplification Aluminum: [Ne]3s23p1  This tells us that there are 2 electrons in the 3s orbital and 1 electron in the 3p orbital so aluminum has a total of 3 valence electrons Calcium: [Ar]4s2 valance electrons: 2 Manganese: [Ar]4s23d5 Valance electrons: 2 Iodine: [Kr]:5s24d105p5 Valence electrons: 7

Electron Configurations Atoms Al: 1s2 2s2 2p6 3s2 3p1 Ions Al- Gained an electron 1s2 2s2 2p6 3s2 3p2 Al+ Lost an electron 1s2 2s2 2p6 3s2 Al3+ Lost 3 electrons 1s2s2p6 Work sheets: Valence Electrons Noble Gases