Question

explain electronegativity. what does its mean that nitrogen(N) is less electronegative than F .?And how we come to know that particular element is more electronegative or less?

Answer 1

Electronegativity is an ability of atom to attract electron either electron density towards itself upon formation of bond with the second atom. An electron density in X-Y pair of atoms is shifted or is located closer to X atom if it has the higher electronegativity than Y atom.
The nitrogen is less electronegative than F means that for N-F bonds, electron density made by valence electrons is closer to the F atom resulting in the negative charge on it.
To find the Electronegativity for the particular element, there is a table containing corresponding data. However, we can use periodic table and the rules about electronegativity to estimate, which say:
1) Electronegativity increases from left to the right side in the period;
2) it decreases from the top to the down in the main group;
3) The most electronegative elements are non-metals (halogens) and the less ones are metals.