Key Notes On History Of Halogens

Halogens are classified as nonmetals. Fluorine and chlorine are gases at room temperature, but bromine is a liquid at this temperature. Iodine and astatine are both solid substances. All of the halogens are extremely reactive, with the most reactive being fluorine, and the least reactive being astatine in nature . When it comes to nature, the elemental form of halogens does not exist. It has been discovered that astatine isotopes are radioactive and have shorter half-lives than others.

All of these substances have something in common: table salt, bleach, fluoride in toothpaste, and chlorine in swimming pools. When you include halogen lights in the mix, the answer becomes more obvious: they all include one or more of the halogens, which are found in Group 7 of the periodic table and consist of five chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At) in nature. In its original meaning, the word “halogen” is taken from the Greek and means “salt-forming.” Because of their extreme reactivity, halogens are only present in the environment in the form of ions or compounds, rather than as solids.

Properties of Halogens

Several physical and chemical features of Halogens will be discussed in this section.

Physical Characteristics

• In the periodic table, the group of halogens is the only group that contains elements in all three recognised states of matter at ordinary temperatures and pressures.
• Fluorine (F) is a colourless, odourless gas.
• Chlorine (Cl) is a gas that is greenish in colour.
• Bromine (Br) is a dark red liquid that is toxic.
• If you heat up iodine (I), you will get a purple vapour instead of a black solid.
• Astatine (At) is a dark solid with a crystalline structure.
• All of the halogens have a distinct and frequently unpleasant odour.
• The elements containing halogens are particularly poisonous.
• Heat and electricity are poorly conducted through these materials.
• The melting and boiling points are quite low.

Chemical Characteristics

Chemical Characteristics of Halogens

• All halogen molecules are homonuclear diatomic, with the exception of radium. The implication of this is that their molecules have two atoms in each of them.
• Inhaling halogens causes them to form negative ions and become very reactive. Halogens contain seven valence electrons, but one electron is absent.
• In the course of their reactions with atoms of other elements, they can obtain an electron.
• Fluorine is one of the most reactive elements that has ever existed on the planet.
• They have intermolecular forces that are rather modest.

Compounds containing halogens

The fact that halogens are extremely reactive is one of their most distinguishing characteristics. Because of this property, they may combine to generate a variety of compounds, including halides, interhalogens, and polyhalogenated compounds. We’ll take a quick look at them in the section below.

Hydrogen Halides

Hydrogen Halides are a kind of chemical compound that contains hydrogen atoms.

These are binary compounds that are generated when halogens react with hydrogen in the presence of oxygen. Generally speaking, if we combine fluorine, chlorine, and bromine, the reaction takes the form shown below:

2HX = H2 + X2 = 2HX

When hydrogen halides are dissolved in water, they form powerful hydrohalic acids. These acids are extremely hazardous.

Metal halides 

Metal halides are compounds that include metal ions.

These are compounds that are generated as a result of the reaction between halogens with metals. Metallic halides can exist as highly ionic compounds, monomeric covalent compounds, or polymeric covalent compounds, amongst other types of compounds. They are often created by either the direct interaction of a basic metal salt with hydrohalic acid or the neutralisation of a basic metal salt with hydrohalic acid.

Interhalogen Compounds 

Interhalogen Compounds are compounds that contain interhalogen atoms.

The reaction of halogen atoms with one another results in the formation of interhalogen compounds. Both their physical and behavioural features and behaviours are intermediates between those of the two-parent halogens. Some qualities, on the other hand, may be different. With the exception of IF7, all interhalogens may be created by directly mixing pure halogens under certain circumstances.

Organohalogen Compounds

These are also referred to as organic halides in some circles. These can be classified as organic compounds containing halogen atoms, which is what they are. A nucleophilic abstraction process is typically used to create organohalogens in a chemical laboratory setting.

Phosphorus-based Polyhalogenated Compounds

Polyhalogenated compounds are defined as compounds that have had several halogens replaced for one or more halogens. They are industrially produced substances, and the vast majority of them are hazardous to people and bioaccumulate in their bodies. PCBs, PBDEs, and PFCs are only a few of the polyhalogenated compounds that have been identified.

Conclusion

Halogens Compounds Bromine and chlorine are commonly used as disinfectants for a variety of applications, including water purification, swimming pools, new wounds, dishes, and surface sterilisation.

Halogen lights include trace quantities of a halogen, such as iodine or bromine, in their composition.Fluoride can be present in a variety of goods, including toothpaste, infant formula, and vitamin supplements, among others.When it comes to the human body, chlorine accounts for around 0.15 percent of total body weight and performs a variety of critical roles in its functioning. Chlorine and bromine compounds are employed as disinfectants and sterilisers in the production of pharmaceuticals.