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.
Write the balanced chemical equation for the reaction of lithium with bromine to produce lithium bromide, LiBr. Include state symbols.
2Li(s) + Br2(g) → 2LiBr(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.
A more reactive halogen can displace a less reactive halogen from solutions of its salts. For example, chlorine is more reactive than iodine. A solution of chlorine can displace iodine from potassium iodide solution:
chlorine + potassium iodide → potassium chloride + iodine
Cl2(aq) + 2KI(aq) → 2KCl(aq) + I2(aq)
The reaction mixture turns darker and iodine solution forms.
A reactivity series can be worked out by carrying out several displacement reactions. Different combinations of halogen solution and salt solution should be tested so that a reactivity series for Group 7 can be worked out:
It doesn't matter whether sodium salts or potassium salts are used - it works the same for both types of salt.