SPM Chemistry Form 5 Notes – Terminology and Concepts: Oxidation and Reduction (Part 6)

by BerryBerryTeacher

in Berry Reference (Notes)

Halogens are non-metal elements listed under Group 17 in the periodic table. The halogen elements contained within Group 17 are fluorine, chlorine, bromine, iodine and astatine. (Within the SPM Chemistry context, you may just focus on the first four halogens mentioned) Hence, you may guessed it already, this post is a continuation Berry Berry Easy‘s SPM Chemistry Form 5 notes on “Oxidation and Reduction” – Part 6. It’s the only group in the periodic table to consist of elements in liquid, solid and gaseous form at S.T.P. Unlike the elements from other groups, halogens typically is not found in its free form in nature, due to its high reactivity. In all, it is rather easy to understand halogens in SPM level and fortunately this short sub-topic is frequently asked in exams of all levels.

SPM Chemistry Form 5 – Terminology and Concepts: Oxidation and Reduction (Part 6)

Rusting of Iron Nails

Rusting of Iron Nails

Displacement of Halogen (Group 17) from Its Halide Solution

Halogen – elements in Group 17 of the Periodic Table

Example: chlorine, bromine and iodine.

Halogen Identification

Halogen Colour in (conc.) aq. solution Colour in (dilute) aq. solution Colour in 1,1,1-trichloroethane
Iodine Reddish-brown Yellow Purple
Bromine Brown Yellow Brown
Chlorine Pale yellow Colourless Colourless

Strength of oxidising agent in halogen

Cl2, Br2. I2

<——— Oxidising power increases

Halide / Halogen Chlorine Bromine Iodine
Potassium chloride - No changes No changes
Potassium bromide Chlorine displace bromine from KBr solution - No changes
Potassium iodide Chlorine displace iodine from KI solution Bromine displace iodine from KI solution -

So stay tune for the next part of this series of “Oxidation and Reduction” on redox reaction by the transfer of electrons from a distance.

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