Texas A&M University (TAMU) BIOL111 Introductory Biology I Exam 1 Practice Exam

As you move across a period in the periodic table from left to right, electronegativity increases. This increase is primarily due to the increase in the nuclear charge as more protons are added to the nucleus of the atoms. As thepositive charge in the nucleus grows, it exerts a stronger attractive force on the electrons in the outermost shell. This stronger attraction allows elements to more effectively attract electrons from other atoms when forming bonds, thus increasing their electronegativity.

Additionally, as you progress across the period, the atomic radius tends to decrease because the added electrons are being pulled closer to the nucleus by the increased nuclear charge. A smaller atomic radius means that the outer electrons are more strongly attracted to the nucleus, which further contributes to the higher electronegativity.

In summary, the combined effects of increased nuclear charge and decreased atomic radius as you move across a period result in an increase in electronegativity.