Question

Rank the elements from highest to lowest values of melting temperature. C, Si, Ge, Sn, Pb

Answer 1

Order of Melting points : C > Si > Ge > Sn < Pb

Due to the small size and high covalent nature in the elemental form the order will become as shown above. In this C,Si,Ge are covalent and Sn, Pb are metallic in nature. The melting point of Sn will be slightly lower than Pb. this due to the increased effective nuclear charge in Pb atom with filling of f orbitals so the screening effect decreases so covalent nature between the atoms increases. Hence the order will be as shown above.