How does the periodic trend of atomic radius relate to the addition of electrons?

1 Answer

The atomic radius actually decreases as you move from left to right in a period (row) of the periodic table.

This might sound a bit confusing, so here are the key things you need to know to understand this concept.

  1. Elements in any period (row) have the same number of energy levels.
  2. Elements further to the right in a row have a larger number of protons in their nuclei. The added protons in the nucleus of an atom will pull the electron cloud more tightly inward and shrink the size of the electron cloud which means you have a smaller atomic radius.

Here is a video which discusses the topic of chemical periodicity. Video from: Noel Pauller