# Covalency and Oxidation Number in Covalent Compounds

## Homework Statement

$NCl_{3}$

What is the Co-valency / Oxidation number of Nitrogen in this Covalent compound ?

## Homework Equations

I think the table of electronegativity might be useful

## The Attempt at a Solution

Nitrogen must be "-3" since it is more electronegative than Chlorine.

The correct answer is +3. How is that possible ?

Clearly Nitrogen is more electronegative than chlorine.

## Homework Statement

$NCl_{3}$

What is the Co-valency / Oxidation number of Nitrogen in this Covalent compound ?

## Homework Equations

I think the table of electronegativity might be useful

## The Attempt at a Solution

Nitrogen must be "-3" since it is more electronegative than Chlorine.

The correct answer is +3. How is that possible ?

Clearly Nitrogen is more electronegative than chlorine.

Chlorine is more electronegative than nitrogen. :)

Chlorine is more electronegative than nitrogen. :)

Nitrogen forms hydrogen bonds in its compounds with Hydrogen attached .

Chlorine rarely forms any hydrogen bonds in any of its compounds .

Here :

Nitrogen forms hydrogen bonds in its compounds with Hydrogen attached .

Chlorine rarely forms any hydrogen bonds in any of its compounds .

Here : View attachment 55758

Allen Scale?

Pauling Scale is the one you need to use.

Allen Scale?

Pauling Scale is the one you need to use.

hmm...doesn't Pauling scale gives us wrong values since according to pauling scale Chlorine being more Electronegative should form Hydrogen bonds .

Borek
Mentor
As if it all mattered...

First: oxidation numbers don't reflect any real property of the element, they are used just for electron accounting.

Second: using electronegativity to predict anything is a quite fuzzy concept, more of a general indication than a hard rule, especially when the differences in electronegativity are small.

Taking both things into account - don't be surprised you get inconsistent predictions trying to apply rule of thumb to border cases.