ii Nonmetals from group V alongacross the period form simple molecules joined by weak intermolecular vanderwaals force The weak intermolecular vanderwaals force require little energyheat to weaken leading to low meltingboiling points The strength of the intermolecular vanderwaals forces decrease with decrease in atomic radius size lowering the meltingboiling points alongacross the period and raising the meltingboiling points down the groupeg