Explain in terms of structure and bonding the properties of ionic compounds: (a) high melting points and boiling points (b) good electrical conductivity when aqueous or molten and poor when solid

Describe the formation of covalent bonds in simple molecules, including ( CH_3OH ), ( C_2H_4 ), ( O_2 ), ( CO_2 ) and ( N_2 ). Use dot-and-cross diagrams to show the electronic configurations in these and similar molecules