A chemist overlays two periodic trend graphs on the same axes: one for atomic radius…
CHEMISTRY · Single correct · A Level · Chemistry · Periodicity and periodic trends · Periodicity and periodic trends
Problem
A chemist overlays two periodic trend graphs on the same axes: one for atomic radius and one for electronegativity. The atomic-radius graph shows deep troughs at Z=2,10, and 18, while the electronegativity graph shows pronounced peaks at Z=9 and 17. Which statement most accurately interprets the relationship between these two properties across a period?
(a) Because the noble gases have the smallest atomic radii, they exert the greatest pull on additional electrons, so electronegativity is highest for the noble gases.
(b) As atomic radius decreases across a period, the nucleus more strongly attracts bonding electrons, so electronegativity rises and peaks in the halogens just before the noble gases.
(c) Across a period, increased shielding outweighs the growing nuclear charge, so electronegativity decreases even as atomic radius becomes smaller toward the right.
(d) Elements with the smallest atomic radii have the lowest electronegativity because their valence shells are filled and they do not attract additional electrons.