Explain the periodic trend of atomic radius acr... - SS2 Chemistry Atomic Structure and Periodicity Question

The atomic radius refers to the size of an atom, typically defined as half the distance between the nuclei of two adjacent atoms in a molecule or crystal lattice.

Across a period (from left to right) in the periodic table, the atomic radius generally decreases. This is primarily due to the increasing number of protons in the nucleus as you move across the period. The increased positive charge exerts a stronger pull on the electrons, bringing them closer to the nucleus and reducing the atomic radius.

Down a group (top to bottom) in the periodic table, the atomic radius generally increases. This is because each successive energy level or electron shell is farther from the nucleus. The addition of more energy levels increases the distance between the nucleus and the outermost electrons, resulting in a larger atomic radius.