Why does electronegativity increase as atomic radius decreases?

When atomic radius decreases, electrons are closer to the nucleus, which means that the attraction that atom has on the orbiting electrons increases, and therefore the electronegativity increases.

is the ability of an element to attract electrons towards itself when it's bonded.

As you move across a period,

• Atomic radius decreases
• Electronegativity increases

Why does this happen?

• The greater the electronegativity, the greater the attraction that atom has on the electrons orbiting around the atom
• The greater the electronegativity, the closer those electrons orbit the nucleus
• Atomic radius is going to decrease because electrons are closer to the nucleus

To know more about electronegativity check this.