Success 24/7 Chemistry: Synthesis and Decomposition Reaction Notes
Synthesis Reactions
(Also known as addition reactions and combination reactions.)
A + B → AB
Two elements or compounds react to make one compound.
Things to be aware of:

When making the new compound, pay attention to the charges of the elements involved.

Do not keep the subscripts from the reactants side.

Don’t forget to balance!
Practice:
Ag
+
S8
→
Al
+
Br2
→
K
+
Cl2
→
Decomposition Reactions
AB
→
A
+
B
A compound decomposes into 2 separate elements or compounds.
Things to be aware of:

If the compound breaks into elements, check to see if either (or both) of them are
diatomics.

Do not keep the subscripts from the original compound…those were from the charges
being “criss-crossed”.

Don’t forget to balance!
Wait…what is a diatomic?
Practice:
Ag2O →
Al2O3 →
Li3N
→