3.1.2—Factors influencing the electronegativities

Greater nuclear charge tends to strengthen the attraction between the nucleus and a bonding electron pair. More protons increase the positive pull, but this effect must be considered with the electron's distance from the nucleus and the shielding provided by inner electrons.

A larger atomic radius places the bonding electron pair farther from the nucleus, so attraction is weaker and electronegativity is lower. A smaller radius brings the bonding electrons closer and strengthens the attraction.

Inner-shell electrons shield the outer region from some nuclear attraction. Greater shielding reduces the effective pull on bonding electrons; therefore proton number alone cannot determine electronegativity. Use nuclear charge, radius and shielding together.

Do not confuse shielding with the number of bonding electrons, or state that every increase in proton number automatically gives a stronger attraction. The combined factor explanation supports the periodic trends on the neighbouring card; numerical bond classification belongs to the later application card.