What is the formula to find the number of lone pair electrons in a covalent molecule ?

Asked by majumdar_indrajit | 31st Mar, 2017, 07:00: AM

Expert Answer:

In a covalent molecule, with only sigma bonds find out the number of bonds formed by the each atoms in the molecule.
Except hydrogen, all the atoms try to form octet for stability.
So each atom should form 4 covalent bonds.
If there are less than four covalent bonds then rest are lone pair of electrons.
 
e.g. In NH3, nitrogen atom forms three covalent bonds. It's atomic number is 7.
Electronic configuration of nitrogen is 1s22s22p3.
So, valence electrons are 5. From those 5 electrons, 3 electrons are used to form covalent nonds with three hydrogen atoms.
Rest two electrons form one lone pair of electrons on nitrogen atom.
Hope, it helps you!!

Answered by Prachi Sawant | 31st Mar, 2017, 11:32: AM

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