A single-displacement reaction is where one element appears to move out of one compound and into another. This is usually written as
A + BX → AX + B
This will occur if A is more reactive than B.

A and B may not have the same change when ions are formed therefore some balancing of the equation may be necessary. For example the reaction between calcium Chloride (CaCl₂) and Sodium (Na) forms Calcium (Ca) and sodium chloride (NaCl)

CaCl₂ + 2Na → Ca + 2NaCl

See also:

• Reactivity series
• Chemical reactions
• Double displacement reactions