Question

1. as you move across a period of the periodic table from left to right, the atomic radii of the elements _______

a) increase.

b) decrease.

c) remain constant.

d) show no pattern.

Explanation:

Analyze the effect of moving left to right across a period

$$ \text{Protons } (Z) \uparrow \implies \text{Effective Nuclear Charge } (Z_{\text{eff}}) \uparrow $$

Determine the effect on atomic radius

$$ \text{Electrostatic Attraction} \uparrow \implies \text{Electron Cloud Pull} \implies \text{Atomic Radius} \downarrow $$

Answer:

• A) increase.
• B) decrease. (Correct answer)
• C) remain constant.
• D) show no pattern.