What is Halogens? | Types, Definition, Structure, Function & Facts
What is Halogens?
The halogens are a group of elements in the periodic table. They are located to the right of the other nonmetals and to the left of the noble gases. Halogen group elements have seven electrons in their outermost shell, giving them many unique properties.
What Elements are Halogens?
The halogens include the five elements fluorine, chlorine, bromine, iodine, and astatine. They make up column 17 of the periodic table.
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What are the similar properties of Halogens?
Halogens share many similar properties, including:
They all form acids when combined with hydrogen.
They are all quite toxic. They easily combine with metals to form salts.
They have seven valence electrons in the outermost shell.
They are very reactive and are electronegative.
They all exist as diatomic (two-atom) molecules when in their pure form.
Phases Under Standard Conditions
Under standard conditions, halogens exist in all three major phases of matter: iodine and astatine are solids; bromine is a liquid; fluorine and chlorine are gases. The only other element that is liquid at room temperature is mercury.
Order of Abundance
All halogens are found in the earth’s crust. Fluorine and chlorine are quite abundant, iodine and bromine are quite rare. Astatine is extremely rare and is considered one of the rarest natural elements on Earth.
Below we have provided the order of abundance in the Earth’s crust:
- Fluorine
- Chlorine
- Bromine
- Iodine
- Astatine
Interesting Facts about Halogens
The name halogen comes from the Greek words “hals” meaning “salt” and “gen” meaning “generating”.
Fluorine is considered to be one of the most reactive elements that exists.
Simple compounds containing halogens are called halides.
Fluorine gas is deadly. Breathing air as small as 0.1% fluorine can also be fatal.
Small amounts of fluoride are used in water and toothpaste to help prevent tooth decay.
The first halogen to be isolated and recognized as an element was chlorine.
Astatine has been used medicinally even though it is radioactive and decomposes rapidly.
Liquid bromine readily evaporates at room temperature giving off an orange vapor.
Bromine has a very strong and unpleasant odor. It takes its name from the Greek word “bromos” which means “stink”.
Despite the fact that fluorine and chlorine are both toxic, small amounts are essential for human health and life. Iodine is also essential for human health.