Question

What would cause an atom to have a high electronegativity value?

Answer 1

We should understand that electronegativity is a measurement of an atom's tendency to attract a bonding pair of electrons. Electronegativity is an atom's property that derives from the difference in electron sharing between two atoms. The atomic size increases as you move down the group.

Complete Step By Step Answer:
When the shielding effect experienced by the electron is low and the valence shell of the atom is either full or nearly full, the electronegativity value is high.
The electrons involved in bonding are known as valence electrons, and electronegativity is a measure of how willing an atom is to attract the electrons present around the bond to itself.
The stronger the electronegativity, the more attracted atoms in an element will be shared. On several scales, we measure electronegativity. Linus Pauling developed the most often used scale. The most electronegative element is fluorine, which has a value of $4.0$ , and the least electronegative element is caesium, which has a value of $0.7$ .
Nonmetals usually have a high electronegativity value. Because alkali metals and alkaline earth metals are electropositive in nature, they form cation, whereas non-metals often gain an electron and form anion, making them electronegative in nature.
As a result, group $17$ has a greater electronegativity value. Because fluorine has a small atomic radius, electronegativity decreases as you move down the group. As a result, the halogen family will have a high electronegativity.

Note:
It is important to understand that electronegativity and atomic size (or atomic radius) are inversely proportional. We find a decrease in electronegativity as atomic size increases. The number of shells increases as atomic size increases, resulting in an increase in effective nuclear charge and, as a result, an increase in atomic radius.