Britannica Sources used in this answer

Why does atomic size increase from carbon to lead in Group 14?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

A color-coded periodic table of the elements displays each element's symbol and atomic number, with categories such as alkali metals, noble gases, halogens, transition metals, and actinoid elements distinguished by different background colors. — carbon group element Modern version of the periodic table of the elements (printable).

The atomic size of elements in Group 14 increases from carbon to lead primarily because of the addition of electron shells as you move down the group.1

While carbon has only six electrons distributed in two shells, lead has 82 electrons arranged in six shells. As the number of shells increases, the outermost electrons are located further from the nucleus. Furthermore, the inner, or intervening, electron shells provide a shielding effect that reduces the electrostatic attraction between the positive nucleus and the valence electrons. Consequently, the atoms become progressively larger as the atomic number increases and more shells are occupied.21