1. Electron Configuration: Ions

2. Electron Configuration - Cations
Cations – atoms that lose electrons - metals
Electron Configuration:
Magnesium – 12 electrons in its neutral state
1s22s22p63s2
Magnesium ion
Loses 2 electrons
New configuration: 1s22s22p6
Notice that the electron configuration is the same as the noble gas Neon
This indicates that by giving 2 electrons away, it obtains an outer octet (stable valence configuration!)

3. Electron Configuration - Anions
Anions – gain electrons – non-metals
Electron Configuration:
Chlorine – 17 electrons in its neutral state
1s22s22p63s23p5
Chlorine ion
Gains 1 electron
New configuration: 1s22s22p63s23p6
Notice that the electron configuration is the same as the noble gas Argon
This indicates that by gaining 1 electron, it obtains an outer octet (stable valence configuration!)

4. Electron Configuration
Both ions obtain a noble gas configuration
This makes the ion and the noble gas isoelectronic
Isoelectronic: when two elements and/or ions have the same electronic configurations with one another
They tend to have similar chemical properties.

5. Isoelectric Examples Li+1 1s2 He 1s2 S-2 1s2 2s2 2p6 3s2 3p6
Ar 1s2 2s2 2p6 3s2 3p6