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The Periodic Table

The Halogens - Uses.

Fluorides are added to toothpaste and sometimes drinking water.
It has been shown that fluorides can
reduce dental decay (damage to teeth) especially in young children.


Chlorine is a disinfectant - it kills bacteria (see iodine below).
It is used to kill bacteria in drinking water and swimming pools.

Chlorine dissolved in sodium hydroxide solution is bleach.
It forms sodium chlorate(I)  -  NaOCl.
Domestic bleach contains about 5% NaOCl(aq).

Chlorine dissolved in water forms
chloric(I) acid  -  HOCl(aq) +  hydrochloric acid  -  HCl(aq).
Chloric(I) acid is also bleach.

Chlorine is used in the manufacture of pesticides,  CFCs and PVC.


Iodine can also be used as an antiseptic to kill bacteria.
There is a difference between an antiseptic and a disinfectant.
They both kill germs but an antiseptic is safe to use on the skin
whereas a disinfectant will damage skin cells.
Iodine dissolved in alcohol (ethanol)
was commonly used as an antiseptic in the past.
It was called "Tincture of Iodine".

Iodine plays an important role in the body (see uses of potassium iodide).

 

Silver bromide and silver iodide are sensitive to light
and are used in photographic film.
Silver bromide is almost white, and when light falls on it,
it splits up into silver metal and bromine.
The silver metal appears as a black mark on the film,
producing a black and white (monochrome) negative.


See also the uses of sodium chloride and potassium iodide.

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