What is atomic radii and how is this impacted in ions?
Atomic radii is the distance from the nucleus to the outmost electron probability. Losing electrons will decrease the atomic radii and gaining electrons will increase the atomic radii.
The nucleus contains the protons the positive force of the atom. The more positive force the more electrons will be pulled toward the nucleus. This is why as the atomic number increases across a period the atomic radii decreases.. Lithium number three is larger than Neon number 10. because the electrons are in the same electron shell but have less attraction to the nucleus.
However if Lithium atomic number three loses an electron creating a positive ion of +1 there are still three positive charges pulling on what is now only two electrons which are in a smaller electron shell, so the + 1 ion is much smaller than the atomic radii of the Neutral atom.
If Flourine atomic number nine gains an electron creating a negative ion -1 there are still only nine positive protons pulling on the electrons. But now there are ten electrons that are being pulled in by the same positive charge so the pull is not as strong. This makes the -1 ion bigger than the neutral atom.