Explain why the elctrical conductivity of Group 1 elements (alkali metals) is higher than group 7 elements?

Answer 1

Group I elements are metals, and so held together by metallic bonding. This means that the solids are crystals with the atoms held together by a "sea" of electrons. When you pass electricity through them, the electrons flow through the crystal. By contrast, Group 7 elements are all covalent nonpolar molecules, F2, Cl2, Br2, I2, At2. Nonpolar molecules do not conduct electricity.