Why group 2 metal is smaller than group 1 metal?

1 Answer
1s2s2p
Apr 18, 2018

Let's use sodium (#"Na"#) and magnesium (#"Mg"#) for example.

The charge on the nucleus of #"Mg"# is one greater than that of #"Na"# and so would have a greater pull on the electrons around it which bring the outer electrons closer to the nucleus. #"Mg"# also donates 2 electrons whereas #"Na"# donates 1, which helps reduce the size of the atom.

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