C1 | C2 | C3 | C4 | C5 | C6 | C7 | C8 | C9 | C10
Made by
How & why
Exams (dutch)
Tests (dutch)
Periodic table
Solvabillity table

ThinkQuest Chemistry in room 11 > Chapter 9 > Information


Salts can be categorised as pure materials. They are dull and brittleand they have very high melting and cooking points. They conduct electricity when they are melted or in a solution.
Salts are not made up of molecules but ions. Ions are electrically charged atoms.
The best known example sodium-chloride which is the main part of cooking salt.
Sodium-chloride is not made up of sodiumatoms and chlorideatoms but ions.

These ions are, in their solid phase, very regularly organised.

Sodium-chloride consists of Na+ and Cl- ions that attrackt eachother. The substance is therefore neutral because the negative charge and the positive charge are the same. So the ratio of Na+ and Cl- ions is 1:1 so the conclusion must be there are the same number of positive and negative ions.
This means that the formula should be (Na+)1(Cl-)1 . The index 1 is not noted and this means that the brackets are not needed. To make it even more easy the formula Na+Cl- is simplified to NaCl.

There are about 100,000 known salts and they all have a high meltingpoint. Stalgmites and stalagtites in caves are examples of salts. They are mainly made up of a salt called calcium carbonate or chalk. Other examples of well-known salts are: plaster stone, copper sulphate, marble, bauxite(alluminium-ore) and rust.

 To determine the formula for a salt we first need to know the charge of the ions in the salt. This is easy for NaCl because Na has +1 and Cl has 1. Bur there are other salts with different charges. Just look at the table. 

The ions of metals (which always have the same ion-charge) are given the name of the metal.
The ion of potassium (K+) is called the potassium ion.
The name of an ion with more than one ion-charge will get a roman numeral added. The roman numeral denotes the charge of the ion. In this way Fe2+ is called the iron(II)ion A negative ion will get the suffix: -ide.

Bromine            bromide-ion
Chlorine            chloride-ion
Iodine              iodide-ion
Oxygen            oxide-ion
Sulphur            sulfide-ion 

To get the formula of a salt there are a number of steps.

find the charge of the ion involved.
write down the ions next to eachother (the metal-ion always in front).
the compound must be electrically neutral so determine the smallest ratio of ions necessary.
note the ratio-numbers to the right of the ions.
If the ratio-number is one, leave it out.

Besides simple ions there arealso complex ions. A complex ion is an electrically charged particle which consists of more than one atom. You will need to know the following complex ions:

Ammonium NH4+
Carbonate CO3 2-
Phosphate PO4 3-

Hydroxide OH-
Nitrate NO3-
Sulphate SO4 2-

Back to top






Dutch Version