Question

which of the following elements has the smallest atomic radius?
chlorine
sulfur
selenium
bromine

Explanation:

Atomic radius trends: In a period (horizontal row), atomic radius decreases from left to right due to increasing nuclear charge attracting electrons more strongly. Chlorine (\(Cl\)) and sulfur (\(S\)) are in period 3, selenium (\(Se\)) is in period 4, bromine (\(Br\)) is in period 4. Among \(Cl\) and \(S\) (same period), \(Cl\) is to the right of \(S\). Also, in a group (vertical column), atomic radius increases from top to bottom. Chlorine is above bromine and selenium in the periodic table. So chlorine has the smallest atomic radius.

Answer:

chlorine