Question

Which statement describes a periodic trend of atomic radius?

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A. It tends to decrease from left to right across a period.
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B. It remains the same within a period.
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c. It remains the same within a group.
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D. It tends to decrease from top to bottom of a group.

Answer 1

The atomic radius decreases from left to right across a period due to increasing nuclear attraction and increases from top to bottom down a group as the number of energy levels increases.

Step-by-step explanation:

The statement that accurately describes a periodic trend of atomic radius is that the atomic radius tends to decrease from left to right across a period. As the atomic number (Z) increases within a period, more protons are added to the nucleus while electrons are added to the same principal energy level. This results in a greater nuclear attraction, pulling the electrons closer to the nucleus and thus decreasing the atomic radius. Conversely, down a group, the atomic radius tends to increase as the principal energy level of valence electrons increases, causing the electron cloud to expand and the atom's size to increase.

Answer 2

Answer:A. It tends to decrease from left to right across a period

Explanation: This trend is caused by the increase number of protons in an atoms nucleus when moving across a period. The protons pull the electrons towards the nucleus causing the atomic radii to shrink and gets smaller or also called as electron shielding.