Question

What is the valence electron configuration of the halogens? Why do the boiling points and melting points of the halogens increase steadily from${\mathbf{\text{F}}}_{\mathbf{\text{2}}}$to${\mathbf{\text{I}}}_{\mathbf{\text{2}}}$?

Short answer

The valence electron configuration of the halogens is:${\text{ns}}^{\text{2}}{\text{np}}^{\text{2}}$ .

The boiling and melting points of the halogens increases suddenly due to the increasing number of electrons in the molecule and also the increasing surface area of the molecule.

Step-by-step solution

Define Valence electron:

The electron lying in the outermost shell of an element is called as a valence electron.

Observing why boiling and melting points if halogen increases steadily?

Group$7A$ elements, fluorine chlorine , bromine iodine , and astatine are said to be the halogens.

Fluorine and chlorine are the poisonous gases, bromine is a toxic one, volatile liquid , and iodine is said to be a sublimable solid.

They are said to be the most reactive non-metallic elements.

The Group$7A$elements have the valence electron configuration as${\text{ns}}^{\text{2}}{\text{np}}^{\text{2}}$.

The features that is to be noted include their high ionization energies and their high electronegativities and electron affinities.

Their electron affinities are high due to the incoming electron that can occupy an orbital of an incomplete valence shell and experience a strong nuclear attraction.

The boiling points and melting points of the halogens increasessteadily down the group just due to the increasing number of electrons in the molecule and the increasing surface area of the molecule.

Therefore,valence electron configuration of halogens is: ${\text{ns}}^{\text{2}}{\text{np}}^{\text{2}}$.

The boiling and melting points of the halogens increases suddenly due tothe increasing number of electrons in the molecule and increasing surface area of the molecule.