Consider the elements: Na, Mg, Al, Si, P. b. Which element has the smallest atomic radius?

Key Concepts

Atomic Radius

The atomic radius is a measure of the size of an atom, typically defined as the distance from the nucleus to the outermost electron shell. It can vary depending on the type of bond the atom is involved in, but generally, atomic radius decreases across a period in the periodic table due to increased nuclear charge, which pulls electrons closer to the nucleus.

Periodic Trends

Periodic trends refer to predictable patterns in the properties of elements as you move across or down the periodic table. For atomic radius, the trend shows that it decreases from left to right across a period and increases from top to bottom within a group, influenced by factors such as effective nuclear charge and electron shielding.

Effective Nuclear Charge

Effective nuclear charge (Z_eff) is the net positive charge experienced by an electron in a multi-electron atom. It accounts for the shielding effect of inner electrons, which reduces the full nuclear charge felt by outer electrons. A higher Z_eff leads to a smaller atomic radius, as electrons are drawn closer to the nucleus.