Question

1. which transition metal has the smallest atomic radius? (put the symbol)

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1. which noble gas would have the smallest atomic radius?

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Explanation:

Step1: Recall atomic - radius trends

Atomic radius decreases across a period and increases down a group in the periodic table.

Step2: Identify the transition - metal

Among transition metals, as we move across the period, the effective nuclear charge increases, pulling the electrons closer. The transition metal with the smallest atomic radius is Scandium (Sc), but in the later transition - metal series, the lanthanide contraction causes Zr, Hf, etc. to have similar radii. However, generally, for the main transition - metal series, the smallest atomic radius is for Sc.

Step3: Identify the noble gas

Among noble gases, helium (He) is in the first period. Since atomic radius decreases across a period and increases down a group, He has the smallest atomic radius among noble gases.

Answer:

1. Sc
2. He