How to Name Compounds in Inorganic Chemistry
The naming of compounds otherwise known as the nomenclature of compounds follows a standard method of nomenclature called the International Union of Pure and Applied Chemistry (IUPAC).
Though the British curriculum and IGCSE exam still accept British nomenclature and equally IUPAC nomenclature, so it is important you know the two nomenclatures.
I will start by explaining the British nomenclature and then down to the IUPAC nomenclature.
I will like you to know how the radicals are named;
Must Know/s in Nomenclature of Compounds
SO42- is called sulfate
CO32- is called carbonates
NO3– is called nitrates
MnO4– is called mangannate
CaCO3 is called Calcium Carbonate
You need to name the metal first i.e cations
K2CO3 is called Potassium Carbonate
MgCO3 is Magnesium Carbonate
CuCO3 is Copper II carbonate
PbCO3 is Lead II carbonate
Do you know why in the last two compounds, I had to mention the valency of the metals?
It is because the metals are transition metals and you need to mention the valency i.e the state of the metal in the compound. This is crucial because transition metals have variable oxidation states.
I talked about this in balancing chemical equations and forming compounds by exchange of valencies.
I will love to talk about the IUPAC nomenclature of these compounds but please I need to emphasize that learning how to name compounds in organic chemistry is different from naming compounds in inorganic chemistry.
There are simple steps required in naming compounds in inorganic chemistry and this post will combine both namings of compounds using IUPAC nomenclature and British nomenclature. However, this is not about the naming of compounds in organic chemistry.
Steps required in naming compounds in inorganic chemistry-IUPAC nomenclature
- When naming compounds, start with metallic ion or ammonium ion
E.g NaCl –Sodium Chloride KBr-Potassium Bromide
2. When naming Binary compounds, the compound should nd with the second element.
However, the second element should end with –ide.
E.g oxygen ends with oxide, fluorine ends with fluoride, chlorine with chloride, etc
NaBr – Sodium bromide, KCl-Potassium Chloride, MgI2-Magnesium iodide
Have you wondered how we form the compounds? No worries, I did a full post on how to form the
formulae of compounds.
3. When naming compounds containing three elements, you need to name the first element first, last or third element, and middle element last.
But you will need to determine the oxidation state of the middle element before you can properly name the compound.
Take a look at some examples
British nomenclature says Calcium Carbonate
IUPAC nomenclature says otherwise
Calcium trioxocarbonate IV
But how did we deduce the oxidation state.
Take a look
Nomenclature of compounds of some compounds
You need to calculate the oxidation state of carbon.
Using the valencies of other elements except for Carbon
2(1) + C + 3(-2) = 0
2 + C- 6 = 0
C = 6-2 =4
IUPAC name is Potassium trioxocarbonate IV
British name is Potassium carbonate
2 + 2N + 6(-2) = 0
2 + 2N -12 =0
2N = 12-2 =10
N = 10/2
IUPAC nomenclature is Calcium trioxonitrate V
British name is Calcium nitrate
IUPAC nomenclature is Sodium tetraoxosulphate VI
British nomenclature is Sodium sulfate
Recall that we need to calculate the oxidation of carbon first before naming the compound in IUPAC Nomenclature
IUPAC nomenclature is Carbon II oxide
British nomenclature is carbon monoxide
IUPAC Nomenclature is Carbon IV oxide
British nomenclature is carbon dioxide
Please take note of the compounds of transition metals; you need to mention the state or valency of the transition metals.
IUPAC Nomenclature is copper II oxide
British nomenclature is cupric oxide
IUPAC Nomenclature is Copper I oxide
British nomenclature is cuprous oxide
IUPAC Nomenclature is iron II chloride
British nomenclature is Ferrous chloride
IUPAC Nomenclature is iron III chloride
British nomenclature Ferric chloride
Please note that naming binary compounds is very easy
MgCl2 is Magnesium Chloride
KCl is potassium chloride
CaO is Calcium oxide
MgO is Magnesium oxide
AgBr is Silver bromide
CaI2 is Calcium iodide
In conclusion, it is important I emphasize this again; nomenclature of compounds in inorganic chemistry is different from naming compounds in organic chemistry.