A chemical reaction
is a process that leads to the transformation of one set of chemical substances
to another. Classically, chemical reactions encompass changes that only involve the positions of electrons
in the forming and breaking of chemical bonds
, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation
. Nuclear chemistry
is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes may occur.