The horizontal rows of the table are called periods and each of their elements have the same number of electron shells. The columns (groups or families) contain elements that have the same number of electrons in their outermost shell, which results in very similar chemical properties. Some of these groups are highlighted.
The atomic radius is a periodic property.
Learning objectives
To observe the periodicity of atomic radii.
How to use the animation
Rollover the element to see their names and atomic radii.