what is meant by polar covalent compound?

ICSE Class 10 Answered

what is meant by polar covalent compound?

Asked by aishanidas009 | 08 Jun, 2018, 10:54: AM

Expert Answer

Polar covalent compounds:

These are the compounds which are formed between dissimilar atoms, whose electronegativity difference more than zero but not high.

Due to electronegativity difference, the shared pair between these atoms is shifted towards the more electronegative atom, thereby developing a partial negative charge (-δ) on the more electronegative atom and partial positive charge (+δ) on the less electronegative atom. Hence the bond becomes polar, and such compounds are known as polar covalent compounds.

let's understand when a covalent compound is polar,

This happens when bonded atoms are dissimilar atoms with little difference in their electronegativity.

For example HCl ( electronegativity of H=2.2 and Cl = 3.16)

The difference in their electronegativity is 3.1-2.2 = 0.9 which is more than 0, hence the nature of bond will be polar

Since Cl is more electronegative than hydrogen it will attract the shared pair of electrons towards itself, thereby developing a slight negative charge (δ−) on Cl and (δ+) charge

But when HCl is in its gaseous form it will never dissociate, but when we dissolved it into a polar solvent it dissociates to form ions.

H C l space rightwards arrow over leftwards arrow with H subscript 2 O on top space H to the power of plus space plus space C l to the power of minus

This happens because the OH- ion from water molecule will attract the H+ ion of HCl hence as both are oppositely charged they attract towards each other and bond between H-Cl is broken and dissociates to form ions.

Answered by Ramandeep | 08 Jun, 2018, 12:38: PM