Question

compare the trends for atomic radius with the trend for atomic mass. how are they similar? how are they different?

Explanation:

Atomic radius and atomic mass both generally increase down a group in the periodic table due to addition of electron - shells and more protons/neutrons. However, across a period, atomic radius decreases as effective nuclear charge increases pulling electrons in, while atomic mass generally increases due to more protons and neutrons.

Answer:

Similarities: Both generally increase down a group. Differences: Across a period, atomic radius decreases while atomic mass increases.