CBSE Class 10 Answered

Electronegativity is a chemical property that describes the tendency of an atom or a functional group to attract electrons (or electron density) towards itself. An atom's electronegativity is affected by both its atomic number and the distance that its valence electrons reside from the charged nucleus. As the effective nuclear charge acting on the valence shell electrons increases across a period, the tendency to lose electrons will decrease. Hence, non-metals tend to form bonds by gaining electrons and are electronegative in nature.

Electropositivity is a measure of an element's ability to donate electrons, and therefore it gives rise to positive ions; the greater the metallic character of an element, the greater the electropositivity. Down the group, the effective nuclear charge experienced by valence electrons is decreasing because the outermost electrons are farther away from the nucleus. Therefore, these can be lost easily. Hence electropositive character increases down a group.