Question

Why does hydrogen molecule exist while helium molecule does not exist for 0?

Answer 1

Answer:

H₂ is formed due to combination of two hydrogen atoms. Atomic number of hydrogen is 1 .

Hence it’s electronic configuration is 1s¹.According to valence bond theory,halfilled atomic orbitals can overlapp to form a bond.Thus two hydrogen atoms along with halffilled 1s orbital,overlapp with each other to form H₂ molecule. H₂ is formed dew to s-s overlapp.

Whereas atomic number of helium is 2 .It’s electronic configuration is 1s².Filled orbital can not overlapp and hence cannot form a bond.Hence diatomic helium i.e.He₂ molecule does not exist .

Answer 2

Explanation:

Hydrogen forms to attain the stability by forming the configuration of He by filling its valence shell with 2 electrons

Helium has only one shell K which us already filled with 2 electrons

So He2 doesnt form

H2 can be formed