Question

Element in 2nd period which doesn't follow the order

Answer 1

The second period contains the elements lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, and neon. ... Period 2 elements obey the octet rule in that they need eight electrons to complete their valence shell.

but lithium , beryllium and boron select duplet configuration i knew onlyy..this much

Answer 2

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The second period contains the elements lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, and neon. ... Period 2 elements obey the octet rule in that they need eight electrons to complete their valence shell.

but lithium , beryllium and boron select duplet configuration i knew onlyy..this much