Why be and Mg not chemically inactive

[Maroon Ray]

Be has 4 electrons, thus the electronic
configuration is 1s2 2s2
Mg has 12 electrons, thus the electronic
configuration is 1s2 2s2 2p6 3s2
Both Be and Mg have
closed subshells. Why are they not chemically
inactive (inert)?

 

[mathman]

To be chemically inert, the element needs closed shells, not subshells. Also, in recent years, compounds involving the heavier inert gases (xenon and krypton?) have been formed.