What are halogens? Where are they located in the periodic table?

Halogens are a group of chemical elements that belong to Group 17 (formerly Group VIIA) of the periodic table. This group is also known as the "halogen group." The word "halogen" itself comes from Greek words that mean "salt-former," which is appropriate because halogens are known for their tendency to form salts when they react with metals.

The halogen group includes the following elements:

Fluorine (F) - Atomic number 9
Chlorine (Cl) - Atomic number 17
Bromine (Br) - Atomic number 35
Iodine (I) - Atomic number 53
Astatine (At) - Atomic number 85
These elements share several common characteristics:

They have seven valence electrons in their outermost electron shell, which makes them highly reactive.

They tend to form negatively charged ions (anions) by gaining one electron to achieve a stable electron configuration with a full set of eight valence electrons, similar to the noble gases.

Halogens are diatomic in their natural state, meaning they exist as molecules with two atoms bonded together (e.g., F2, Cl2, Br2, I2).

They are highly reactive and can readily form compounds with other elements, especially metals, to create salts and other compounds.

Halogens become less reactive as you move down the group, with fluorine being the most reactive and astatine the least.

Halogens play essential roles in various chemical processes and are used in a wide range of applications, including disinfection (chlorine), pharmaceuticals (iodine), and organic synthesis (bromine). They are also vital components of many minerals and natural compounds found in the Earth's crust and atmosphere.