trains students in the state symbols for reactants and products in a chemical equation. Elements in their elemental form and compounds are divided into covalent and ionic compounds for classification and easier identification of relevant state symbols.

1. CHEMICAL EQUATIONS
Practice your covalent bonding to find how the non-metal atoms such as the group 7 ones
form molecules using covalent bonding to get octet configuration
O2 and Cl2
State symbol of atoms in their elemental forms
What are the state symbols of metals from group I, II, III?
Solid
Group IV What are the state symbols of carbon?
carbon is usually in the form of graphite which is a solid, the state symbol is C(s).
Group V nitrogen atoms form N2 molecule which isin gaseous state at room temperature
Phosphorus is a solid at room temperature. the state symbol is P(s).
Group VI oxygenatoms form O2 molecule which is in gaseous state at room temperature
Sulphur is a solid at room temperature. Its state symbol is S(s).
Group VII flourineatoms form F2 molecule which is in gaseous state
Bromine atoms form Br2 molecule which is in liquid state. Its state symbol is Br2(l).
Iodine atoms form I2 molecule which is in solid state. Its state symbol is I2(s).

2. Group VIII  the noble gases are monoatomic, which means they exist as single atoms in
the gaseous state.
Next you need to know the state symbol of the commonly seen compounds.
Compounds are grouped into two types – ionic and covalent
As you know, ionic compounds are made up of oppositely charged ions and you must be able
to recognise from their formula that they are ionic compounds.
On the other hand, covalent compounds are made up of all non-metals atoms.
Insoluble ionic compounds are solids are room temperature because they have very high
melting points. But soluble ionic compounds may be in aqueous state, which means that they
are dissolved in water.
Most covalent compounds are either in liquid or gaseous states, except a few exceptions like
sand (SiO2). But acids (the big 3, hydrochloric acid, nitric acid and sulphuric acid) are usually
in aqueous state.
Sort the following compounds into covalent and ionic compounds and their state symbols at
room temperature.
H2O HCl
CO2 CH4
CaCO3 H2SO4
CaO NaOH
Al2(SO4)3 HNO3
Ca(OH)2 CCl4
Use the solubility table below to help you!
reagents soluble insoluble
Carbonates sodium, potassium & ammonium the rest
Calcium, sodium, potassium &
Bases
hydroxides ammonium the rest
Metal Oxides Group I metals’ oxides only Other metals
Non-metal Oxides Most CO, NO, SiO2
chlorides the rest lead, sliver
salts Nitrates ALL soluble -
sulphates the rest barium, lead

3. Try to balance the following equations, the key is to balance those atoms that appear only
once first, and then balance hydrogen and oxygen atoms last.
H2+ O2H2O
CaO + HClCaCl2 + H2O
CH4 + O2 CO2 + H2O
N2 + O2NO2
H2SO4 + NaNa2SO4 + H2O
CH4 + Cl2CCl4 + HCl
Na2O + H2O NaOH
Na + H2O NaOH + H2
Write out the following chemical equations
Calcium oxide + nitric acid  calcium nitrate + water
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