Today we’ll be discussing single replacement reactions. Single Replacement reactions always follow this format:

Element + Ionic Compound → New Ionic Compound + Different Element

Another way to think of them would be this…

So Here’s how it works. We’ll use the Reactants Zn + Cu(NO₃)₂ →  As our example

Step 1: Identify the element as either a Metal or a Non Metal.
–              For our reaction Zn (Zinc) is a metal. So, we’ll write ‘Metal’ under Zn

Zn + Cu(NO₃)₂ →
Metal                        –

Step 2: Determine the charge of the Element.
–              For our reaction, Zn has a charge of +2. So we’ll write that below ‘Metal’

Zn + Cu(NO₃)₂ →
Metal                        –
+2                          –

Step 3: Seperate the Ionic Compound into Cation and Anion and determine the charges
–            In almost all Ionic compounds the Cation is listed first, and it’s almost always a Metal (except when it’s ‘H’)

Zn + Cu(NO₃)₂ →
Metal   Cat.  An.       –
+2       +2     -1          –

Step 4: If the Element is a Metal then it will replace the Cation; It will replace the Anion if it was a Nonmetal.
–              For our example, Zn will replace the Cu. The other element is left standing alone in it’s elemental form.
–              Remember the charges will determine the subscripts. In this case, Zn has a charge of +2 and since NO₃ has a charge of -1, it takes 2 NO₃‘s to make the charges balanced.

Zn + Cu(NO₃)₂ →   Zn(NO₃)₂  + Cu
Metal    Cat.  An.                                –
+2         +2     -1                                 –

That’s all folks.