Question

size trends
atomic radius
consider your knowledge about the
behavior of particles within atoms and
atomic radius trends.
i. the atomic radius decreases from left to
right across a period due to the addition of
electrons to further energy levels.

ii. the atomic radius increases from left to
right across a period due to an increase in
number of valence electrons.

iii. the atomic radius increases from top
to bottom in a group because new
electrons are added to a further energy
level from one period to the next.

iv. the atomic radius decreases from top
to bottom in a group due to an increase in
shielding as additional energy levels are
added.

which statement is true regarding
atomic radius?
statement i
statement iii
statement iv
statement ii

Explanation:

• Statement I is false: Atomic radius decreases left-to-right across a period because increasing nuclear charge pulls electrons closer, not because electrons are added to further energy levels (electrons in the same period occupy the same principal energy level).
• Statement II is false: Atomic radius decreases (not increases) left-to-right across a period due to higher nuclear charge, not valence electron count.
• Statement III is true: Moving top-to-bottom in a group, each element has electrons in a new, higher principal energy level, which is farther from the nucleus, increasing atomic radius.
• Statement IV is false: Atomic radius increases (not decreases) top-to-bottom in a group as new energy levels add shielding, weakening nuclear pull on outer electrons.

Answer:

Statement III