Question

Krypton has a higher melting point than argon because of its:

Answer 1

Answer:

             Krypton has a higher melting point than argon because of its stronger dispersion forces.

Explanation:

                   Dispersion forces also known as London Dispersion forces are found in non polar compounds. These interactions take place in two steps.

Step 1: Instantaneous Dipole:

                                                  In non polar compounds the electron density on atom is symmetrical. When these symmetrical atoms approaches second symmetrical atom, a disturbance in electron densities occur due to repulsion between electrons. Due to repulsion the electrons density change there position and for a small period of time and instantaneous dipole is produced on an atom.

Step 2: Induced Dipole:

                                         The dipole produced in step one when approaches another symmetrical atom, the partial positive part (low electron density site) attracts the electron from symmetrical atom and induces polarity in it. In this way the non polar atoms become polar and interacts with each other.

Factors Effecting Strength of Dispersion Forces:

i) Size of Atom / Molecule:

                                           Greater the size of an atom greater will be the dispersion forces and vice versa.

ii) Shape of Molecules:

                                      Greater the branching on molecule, weaker will be the dispersion forces and vice versa.

Conclusion:

                  As the size of Krypton is greater than Argon therefore, it will have stronger dispersion forces and will melt at higher temperature than Argon.