What is the order of melting point of group 18 elements?

CONCEPT:

Melting Points of Group 18 Elements

• Group 18 elements, also known as noble gases, have weak van der Waals forces between their atoms.
• The melting points of these elements generally increase with an increase in atomic number.
• This trend is due to the increase in the size of the atoms and the corresponding increase in the strength of van der Waals forces.

EXPLANATION:

• Considering the noble gases in Group 18:

  He, Ne, Ar, Kr, Xe

• As we move down the group from helium (He) to xenon (Xe):
  • The atomic size increases.
  • The van der Waals forces between the atoms become stronger.
  • As a result, the melting points increase.
• The order of melting points from lowest to highest is:
  • He < Ne < Ar < Kr < Xe

Therefore, the correct order of melting points of Group 18 elements is: He < Ne < Ar < Kr < Xe.