Size and Mass

We've told you a little about the size and mass of atoms. But now it's time to go into more detail.

Size

Since we're still talking size here, another important atomic measurement is atomic radius. A radius, as you know, is a line drawn from the center of a circle to its circumference (or from the center of a sphere to its surface). 
Unlike a ball, an atom doesn't have a fixed radius (because of its constantly shifting and orbiting electrons). So the radius of an atom can only be found by measuring the distance between the nuclei of two touching atoms and then dividing that distance by 2.