Halogens

HALOGENS

The following are the elements in the halogen group which we will discuss later:

1. Fluorine (F)
2. Chlorine (Cl)
3. Bromine (Br)
4. Iodine (I)
5. Astatine (At)

Fluorine:

• Fluorine has an atomic number of 9 and is denoted by the symbol F.
• Fluorine was first discovered in 1886 by isolating it from hydrofluoric acid. 
• It is the most electronegative element in the periodic table.
• It has a small atomic radius.
• Its oxidation state is always -1 except in its elemental form, the diatomic state in which its oxidation state is zero.
• Fluorine is extremely radioactive and reacts directly with all elements except helium, neon, and argon.
• In addition, fluorine produces a very powerful oxidant. For example, Fluorine can react with noble gas Xenon and form the strong oxidizing agent Xenon difluoride (XeF₂)

Chlorine:

• Chlorine has the atomic number 17 and the chemical symbol Cl.
• Chlorine was discovered in 1774 by extracting it from hydrochloric acid.
• Chlorine exhibits multiple oxidation states, such as -1, +1, 3, 5, and 7.
• Chlorine has two isotopes Cl-35 and Cl-37
• Sodium chloride is the most prevalent compound of chlorides.

Bromine:

• Bromine has an atomic number of 35 with a symbol of Br. It was first discovered in 1826. At room temperature bromine is a reddish-brown liquid.
• Its oxidation state varies from -1, +1, 3, 4 and 5.
• Bromine is more reactive than Iodine, but not as chlorine.
• Bromine also has two isotopes Br-79 and Br-81.
• Like all of the other halogens, bromine is an oxidizing agent and very toxic.

Iodine:

• Iodine has the atomic number 53 and symbol I.
• Iodine has oxidation state -1, +1, +5 and +7.
• At room temperature, it appears as a violet solid.
• Iodine has one stable isotope I-127.
• It was first discovered in 1811 through the use of seaweed and sulfuric acid.

Astatine:

• Astatine is a radioactive element with an atomic number of 85 and the symbol At. Its possible oxidation state includes -1, +1, +3, +5 and +7.
• It is the only halogen that is not a diatomic molecule and it appears as a black, metallic solid at room temperature.
• Astatine has a short half-life, no longer than a couple of hours.
• It was discovered in 1940 by synthesis.