The halogen family comprises a collection of non metallic elements. This series of elements fall under Group 17 of the periodic table of chemical elements. The members that are a part of the halogen family include chlorine, fluorine, iodine, bromine, and astatine. Ununseptium is not a naturally occurring element, and is also believed to be a halogen. A unique characteristic of halogens is that it is the only group in the entire periodic table that is composed of elements that belong to all three classical states of matter (solid, liquid, and gas), when kept under standard conditions of pressure and temperature.
- All these elements are extremely reactive.
- Due to this tendency towards high reactivity, the halogens cannot exist in the environment as pure elements. They are usually found occurring as compounds or as ions.
- Most halogen ions and atoms can be found in combination with other compounds present in the sea or mineral water. This is because halogen elements tend to create salt when they come in contact with the metals and combine with them to form compounds.
- As mentioned previously, halogens are the only elemental group in the entire periodic table, which is composed of elements that belong to all three classical states of matter (solid, liquid, and gas). This is proved by the fact that when kept under room temperature and normal pressure, astatine and iodine take the form of solids, bromine appears as a liquid, and chlorine and fluorine occur as gases.
- All halogen elements form hydrogen halides, which are very strong acids, when they combine with hydrogen, and form binary compounds.
- On reacting among themselves within the halogen group, these elements form diatomic inter halogen compounds.
- Halogens get their high tendency to react with other matter due to high levels of electronegativity of their atoms, which is a result of the high effective nuclear charge of all halogen atoms.
- Biological lifeforms may experience harmful effects if they are exposed to either large quantities of halogens, or to moderate quantities for long durations.
All halogen characteristics can be attributed as occurring due to the innate physical and chemical properties that the elements of this group possess in common. The following table summarizes the various properties of halogens.
|Physical Properties of Halogens||Chemical Properties of Halogens|
|They exist in all three classical states of matter - solid, liquid and gas.||All halogens are electronegative. They gain electrons very fast making them most reactive of all chemical elements.|
|Halogens are diatomic when kept under room temperature.||Halogens easily dissociate into atomic particles and can combine with surrounding elements to form compounds.|
|Halogens like fluorine, bromine and chlorine are poisonous in nature, each having different levels of toxicity.||When combined with hydrogen, halogens produce halides which are very strong acidic compounds.|
|No halogen is completely colorless.||Typical to non-metals, halogens have very low melting and boiling points.|
|In their solid forms, all halogens have a brittle texture.||Halogens are poor conductors of heat and electricity, irrespective of their physical state.|
Uses of halogens include utilizing them as key components for manufacturing disinfectants, refrigerants, insecticides, food colorings, dyes, petroleum products, flame proofing agents, etc. Halogen lamps are manufactured by filling inert gas, containing a small amount of either iodine or bromine, inside a bulb that has a tungsten filament. The halogen and tungsten react in such a way that the lamp can work at a higher temperature, without the bulb getting darkened. Among all the members, the uses of astatine have not been ascertained yet.