Question

What's is pauling's scale?

Answer 1

Pauling scale is a numerical scale of electronegativities based on bond-energy calculations for different elements joined by covalent bonds. Electronegativity is the power of an atom when in a molecule to attract eletrons to itself.
Electronegativity is a property of a chemical element, not of an electron. It is a measure of the ability of an atom of an element to attract the pair of electrons in a chemical bond towards itself. This ability is usually measured on the Pauling scale.

Fluorine is the most electronegative element in the Universe with a Pauling electronegativity value of 4. An atom of fluorine will attract the bonding pair towards itself (assuming the atom to which it is bonded is not another fluorine!) and become slightly negatively charged.

Pauling used bond dissociation energies to define electronegativities.

He defined the difference in electronegativity between atoms A and B as:

χA−χB=eV−12√Ed(AB)−12[Ed(AA)+Ed(BB]

The dissociation energies Ed of the A-B, A-A, and B-B bonds are expressed in electron volts, and the factor eV−½ is used to make the result dimensionless.

The reference point defines the electronegativity of hydrogen as 2.20.

This makes the scale go from 0.7 (least electronegative) to 3.98 (most electronegative).


Electronegativity is the tendency of an atom to attract electrons from other atoms it has bonded with.

You may remember the octet rule, which states that elements want to have the same electron configuration as a noble gas.

The electronegativity, in essence, measures how this happens.

For example:

The most electronegative atoms are near fluorine because they have the least electron shielding and need only 1, 2, or 3 electrons to fill their outer shell (octet rule).
The least electronegative atoms are near francium because they have the most electron shielding and will donate 1, 2, or 3 electrons to fulfill the octet rule.