S27 Atomic radii.

Aim: To show how the size of the atom of elements varies according to the position of the element in the periodic table.

 

   The size of atoms can be defined in various ways.
The covalent radius is defined as half the distance between the mid points of the nuclei of two identical atoms joined by a single covalent bond. It is the covalent radii which are shown on the overlay illustration (the values being expressed in Angström (=0.1nm in S.I. units). The circles give a relative visual impression of the atomic radii (1).
In the table the atomic radius can be seen to increase on moving down a group and to decrease from left to right across a period.

Reference:
1) H.F. Holtzclaw and W.R. Robinson, College Chemistry, D. C. Heath and Company Lexington, (1988)