Atoms and Molecules Notes

• The atoms of Noble gases have stable (ns², np⁶) configuration, there octet duet in the case of Helium is complete therefore they do not combine.

• Atoms of other elements combine in order to complete their respective octet (attain 8 electrons in the valence shell).
• They try to complete their octet either by gaining/losing /sharing electrons.

• An ion is a positively or negatively charged atom (or group of atoms).

Cations:

• Cations are positively charged species and are formed when a metal atom loses electrons.

• Cations are represented by symbol of element and positive sign as superscript (A⁺).

Sodium Cation:

Potassium Cation: