Why is Na atom bigger than the atoms of both lithium and magnesium ?

Why do atoms combine?

Write any two similarities between Lithium and Magnesium.

Give any two diagonal relationship between Lithium and Magnesium.

Lithium, sodium and potassium form a Dobereiner's triad. The atomic masses of lithium and potassium are 7 and 39 respectively. Predict the atomic mass of sodium.

Explain the diagonal relationship between Lithium and Magnesium.

Give one suitable reason for diagonal relatioship of lithium with magnesium.

Explain the diagonal relationship between LIthium and Magnesium

Why is an atom electrically neutral?