Question

which element has the smallest atomic radius?
calcium
potassium
scandium
titanium

Explanation:

Atomic radius decreases across a period from left - to - right in the periodic table. Calcium (Ca), potassium (K), scandium (Sc), and titanium (Ti) are all in the fourth period. Potassium is in group 1, calcium in group 2, scandium in group 3 and titanium in group 4. As we move from group 1 to group 4 in the fourth period, the effective nuclear charge increases, pulling the electrons closer to the nucleus and decreasing the atomic radius.

Answer:

D. titanium