A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding. As the valency of germanium is 4, it can share 4 electrons of neighboring atom to complete the octet. Hence, Ge has covalent bond. NaCl is an example of an ionic bond and helium and copper both have valency 2 and 1 respectively.