Question

Electrons in shells of first 18 elements in periodic table

Answer 1

Electron configurations and the periodic table
Helium ( He), neon ( Ne), and argon ( Ar), as group 18 elements, have outer electron shells that are full or satisfy the octet rule. ...
Hydrogen ( H), lithium ( Li), and sodium ( Na), as group 1 elements, have just one electron in their outermost shells.