how do u find the lone pair of electrons and bond pair of electrons with the octet rule?

Asked by naveen.mohandas | 19th Sep, 2010, 07:42: PM

Expert Answer:

The octet rule is a simple chemical rule of thumb that states that atoms tend to combine in such a way that they each have eight electrons in their valence shells, giving them the same electronic configuration as a noble gas.
In many molecules, not all of the electron pairs comprising the octet are shared between atoms. The unshared electron pairs are often called lone pairs. Although lone pairs are not directly involved in bond formation.
 
Now, Let us clear the concept by taking an example of NH3.
 

Nitrogen has 5 outer electrons ( shown by red colour). Each of the 3 hydrogens electron is shown by green colour which  are adding another electron to the nitrogen's outer level, making a total of 8 electrons of nitrogen atom in its outer shell in 4 pairs. Because the nitrogen is only forming 3 bonds with hydrogen atom, one of the pairs must be a lone pair.

Answered by  | 19th Sep, 2010, 08:54: PM

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