The halogens react with metals to produce salts (the word 'halogen' means 'salt former'). For example, chlorine reacts with sodium:
sodium + chlorine → sodium chloride
2Na(s) + Cl2(g) → 2NaCl(s)
Sodium and chlorine react vigorously when heated, giving an orange flame and clouds of white sodium chloride.
The halogens become less reactive going down group 7. The reaction of sodium with fluorine will be more vigorous than the reaction between sodium and chlorine.
Write a balanced equation for the reaction of potassium with bromine to produce solid potassium bromide, KBr. Include state symbols.
2K(s) + Br2(l) → 2KBr(s)
The halogens also react with other metals, such as iron. The table describes what is seen when halogens react with iron wool.
|Fluorine||Cold iron wool burns to produce white iron(III) fluoride|
|Chlorine||Hot iron wool burns vigorously to produce orange-brown iron(III) chloride|
|Bromine||Hot iron wool burns quickly to produce red-brown iron(III) bromide|
|Iodine||Hot iron wool reacts slowly in iodine vapour to produce grey iron(II) iodide|
Write a balanced equation for the reaction of iron with chlorine to produce solid iron(III) chloride, FeCl3. Include state symbols.
2Fe(s) + 3Cl2(g) → 2FeCl3(s)
Damp litmus paper is bleached white when it is placed in chlorine. If damp blue litmus paper is used, the paper turns red then white.