In your own words, explain the trend of atomic radius. What is it and why?

Explanation:

Trend of Atomic Radii in Periodic Table :

Atomic Radii Increases Down the group due to increase in Atomic number Atomic Radii Decreases across the period as no. of protons in nucleus keep increasing for successive elements but electrons keep adding in the same shell (energy level) . Thus, increasing effective nuclear charge results in reduced atomic radii across the period .

(Note : There are exceptions to above trend)