Halogen Family Characteristics

Introduction:
Halogens are the group of elements present in the seventeenth group of the Periodic Table. This group is also numbered as 7A group. The elements in order are: -

S.No.	NAME	ATOMIC NUMBER	ATOMIC MASS (amu)
1.	Fluorine (Fl)	9	19
2.	Chlorine (Cl)	17	35.5
3.	Bromine (Br)	35	79.9
4.	Iodine (I)	53	126.9
5.	Astatine (At)	85	210

Halogen Family Characteristics:

The halogens are non-metals. They are electronegative elements, since they tend to gain electrons to form negatively charged ions.
They have the highest values of electro-negativity in their respective periods. Fluorine and Chlorine are gases in state,  Bromine is a liquid, and Iodine and Astatine are solids. Astatine is a very unstable element, and it is found rarely in nature.
The Halogens are all strong oxidising agents since they accept electrons to form compounds. They readily and directly combine with electro-positive elements (metals) to form ionic compounds owing to their strong affinity for electrons. Their last shell or the valence shell, contains seven electrons, and in order to complete its octet they need to gain one electron for each atom. This also causes the Halogens to be one of the most highly reactive elements. Examples of compounds formed between Halogens and metals: -

• Common salt (NaCl) : Reaction Na + Cl → NaCl
• Lithium Fluoride (LiF): Reaction 2Li + F₂ → 2LiF
• Potassium Bromide (KBr): Reaction 2K + Br₂ → 2KBr

Halogens also form covalent compounds:-

• Hydrochloric acid (HCl): Reaction H₂ + Cl₂ → 2HCl.

The color of Halogens varies from top to bottom in the group, the top element Fluorine is the lightest colored, being light yellow, and the lowest element Astatine is the darkest, being black in color.