Sodium chloride has a giant ionic lattice. This formation is due to the ionic bonding, which involves the transfer of electrons from one atom to another to ensure that each atom has a full outer shell of electrons. Sodium will lose the electron to become Na + while chloride will get the electron to form Cl-, While SiCl4 is a cohesive compound, so in solid SiCl4, molecules are bound together by weak inter molecular forces. As a result, ionic compounds have higher melting points. Inter molecular strength is weak, however, requiring less breaking power than ionic bonds, so covalent compounds have lower melting points.