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