• The
chemical atomic weight or the average atomic weight (A) of
an element in nature is given by the equation
• A
= A1p1 + A2p2 + .......+ Anpn
•
• where
A1,
A2,
...... An are the atomic masses
in Daltons of the n isotopes of the element and p1,
p2 ...... pn are the fractional
abundance of these isotopes.