Single Replacement Reactions

In a single replacement reaction, one element replaces (takes the place of) another element in a compound. One reactant is always an element. In many reactions, the element is a metal and the second reactant is a compound. You can write a single replacement reaction in a general form like this:

A + BX --> AX + B

The following animation illustrates this process using actual elements and compounds. Notice that the sodium atoms are replacing the hydrogen atoms in the hydrogen chloride.