1. Types of Chemical Reactions Special Cases of Synthesis & Decomposition
We know the basics, but how about the specifics?

2. Special Types of Synthesis Reactions Metals
Metal + Oxygen → Metal oxide
4Na(s) + O2(g) → 2Na2O(s)
2Mg(s) + O2(g) → 2MgO(s)
Metal + Sulfur → Metal Sulfide
Why the same?
Metal Oxide + Water → Metal Hydroxide
Na2O(s) + H2O(l) → 2NaOH(aq)
MgO(s) + H2O(l) → Mg(OH)2(aq)

3. Special Types of Synthesis Reactions Nonmetals
Non-metals will react with oxygen to form non-metal oxides:
S8(s) + 8O2(g) → 8SO2(g)
C(s) + O2(g) → CO2(g)
Non-metals will also react with Cl2 or Br2 to form chlorides or bromides
P4(s) + 6 Br2(l) → 4 PBr3(l)
Non-metal oxides react with water to form oxyacids:
SO2(g) + H2O(l) → H2SO3(aq)

4. Reactions of Metals with Halogens
Mg(s) + Cl2(g) → MgCl2(s)
This referred to as an oxidation-reduction (REDOX) reaction
Why?
Magnesium is oxidized (electrons are lost)
Chlorine is reduced (electrons are gained)
Cl2 causes Mg to be oxidized and is called the oxidizing agent
Mg causes Cl2 to be reduced and is the reducing agent

5. Decomposition Reactions of Metals
Metal Carbonates (+ heat) → Metal Oxide + CO2(g)
CaCO3 → CaO(s) + CO2(g)
Metal Hydroxides (+ heat) → Metal Oxide + H2O(l)
Ca(OH)2 → CaO + H2O
Does not happen for Group I hydroxides

6. Decomposition Reactions of Metals
Metal Chlorates (+ heat) → Metal Chloride + O2(g)
2 KClO3(s) → 2 KCl(s) + 3 O2(g)
This reaction takes place with a catalyst (a substance added to speed up reaction that is not changed)
Metal Nitrates (+ heat) → Metal Nitrite + O2(g)
2 NaNO3 → 2 NaNO2 + O2(g)
Hydrogen Peroxide (+ catalyst) → H2O(l) + O2(g)