Compounds of halogens

A group of elements known as the halogens includes the elements fluorine, chlorine, bromine, iodine, astatine, and the more recently found radioactive element cesium-137. All of these elements’ physical and chemical properties, with the exception of astatine, have been thoroughly investigated. They are members of group VII of the periodic table, and their physical qualities are nearly flawless in their range of variation.

It is also illustrated by the similarity in the chemical properties of the elements in the group, which is associated with the arrangement of seven electrons in each of the elements’ outer shells of their atomic structures, a similarity which is associated with the arrangement of seven electrons in each of the elements in the group’s atomic structure. All of the members combine to create compounds with hydrogen, and the ease with which union happens diminishes as the atomic weight of the members increases. In a similar vein, the temperatures of production of the different salts fall as the atomic weights of the halogens increase in size. It is striking how closely the properties of halogen acids and their salts are related; the similarity is immediately apparent in organic halogen compounds, but as the compound becomes more chemically complex, the characteristics and influences of other components of the molecule may mask or modify the gradation of properties.

Halogens

Halogens are classified as nonmetals. Fluorine and chlorine are gases at room temperature, whereas 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. When it comes to nature, the elemental form of halogens does not exist. It has been discovered that astatine isotopes are radioactive and have short half-lives.

Types of halogen compounds

Hydrogen Halides

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

Every one of the halogens reacts with hydrogen to generate binary compounds, which are known as the hydrogen halides. These compounds include the following elements: fluorine (HF), chloride (HCl), bromide (HBr), iodide (HI), and astatide (HA) (HAt). When dissolved in water, all of these compounds, with the exception of HF, form powerful chemical acids. Hydrofluoric acid, on the other hand, has extremely damaging characteristics against animal tissue, including human tissue.

All of these acids are extremely hazardous and must be handled with extreme caution. Some of these acids are also frequently utilised in the chemical industry, particularly in the production of chemicals. Because of the great radioactivity of astatine (through alpha decay) and the fact that it easily decomposes into its constituent elements, hydrogen astatide should also be considered a strong acid (hydroastatic acid), but it is rarely included in presentations about hydrohalic acids (hydrogen and astatine).

Metal Halides

The halogens combine with metals to generate a wide variety of compounds. These include highly ionic compounds such as sodium chloride, monomeric covalent compounds such as uranium hexafluoride, and polymeric covalent compounds such as palladium chloride, amongst other substances. It is generally accepted that metal halides are formed through the direct combination of two metal halides or, more typically, the neutralisation of a basic metal salt with a hydrohalic acid.

Interhalogen Compounds

Interhalogen compounds are formed as a result of the reaction between the halogens. In certain ways, diatomic interhalogen compounds such as BrF, ICl, and ClF are similar to pure halogens in that they contain diatomic interhalogens. When it comes to the properties and behaviour of diatomic interhalogen compounds, they tend to be intermediates between those of their parent halogens. Some characteristics, on the other hand, are shared by neither parent halogen. For example, Cl2 and I2 are soluble in CCl4, however ICl is not since it is a polar molecule and hence cannot dissolve in CCl4 (due to the electronegativity difference between I and Cl).

Organic Halides

The halogen atoms found in many synthetic organic compounds, such as plastic polymers, and a few naturally occurring organic compounds are referred to collectively as “organic halides.” Halogenated organic compounds are substances that include halogen atoms. Chlorine is by far the most abundant of the halogens, and it is the only one that humans require (in the form of chloride ions) in reasonably considerable quantities. By mediating the activity of the inhibitory transmitter GABA, chloride ions, for example, play a critical role in brain function and function. Their usage by the body to create stomach acid is also documented. Iodine is required in trace amounts for the creation of thyroid hormones, such as thyroxine, which are essential for normal thyroid function. In contrast, neither fluorine nor bromine are considered to be required for human survival. In addition to organohalogens, the nucleophilic abstraction reaction is used to create them.

Polyhalogenated Compounds

Polyhalogenated compounds are synthetic compounds that have had numerous halogens swapped for one another in the manufacturing process. Many of them are extremely hazardous to humans and bioaccumulate in their bodies, but they have a wide range of potential applications. Among the various polyhalogenated chemicals are the widely recognised PCBs, PBDEs, and PFCs, as well as a slew of additional substances.

Uses of halogen and halogens compound

1. Chlorine and halogens are utilised in a variety of industries, including the chemical, water and sanitation, plastics, pharmaceuticals, pulp and paper, textiles, the military, and the oil industry. Bleaching agents and disinfectants are produced by the reactions of the elements bromine, chlorine, fluorine, and iodine. 

2. During the textile manufacturing process, both bromine and chlorine are utilised for bleaching and shrink-proofing wool. Bromine is also employed in the extraction of gold from ore, as well as in the drilling of oil and gas wells. 

3. It is used as a fire retardant in the plastics sector, and as an intermediary in the production of hydraulic fluids, refrigerating and dehumidifying agents, and hair-waving preparations, among other products. Bromine is also found in military gas and fire-extinguishing fluids, among other things.

4. Oxidizers for rocket fuel systems include the elements fluorine, fluorine monoxide, bromine pentafluoride, and chlorine trifluoride, among others. Aside from these applications, fluorine is also utilised in the conversion of uranium tetrafluoride to uranium hexafluoride, while chlorine trifluoride is used in nuclear reactor fuel as well as in the cutting of oil-well tubing.

5. Calcium fluoride, which can be found in the mineral fluorspar, is the principal source of fluorine and fluorine-containing compounds in nature. It is used as a flux in ferrous metallurgy to increase the fluidity of the slag, and it is also employed in other industries. Calcium fluoride can also be found in the sectors of optical glass and electronic devices.

6. It is possible to manufacture organic and inorganic bromides with hydrogen bromide and its aqueous solutions, and they can also be used as reducing agents and catalysts. They are also utilised in the alkylation of aromatic compounds, which is a chemical reaction. 

7. The chemical element potassium bromide is utilised in the production of photographic sheets and plates. Phosgene gas is required in large amounts for a variety of industrial syntheses, including the production of dyestuffs. Phosgene is also employed in military gas and pharmaceuticals, among other applications. Phosgene can be found in pesticides and fumigants, among other things.

Dangers associated with halogen compounds

1. The physiological effects connected with this group demonstrate the chemical similarities that these elements share in terms of their physical and chemical properties. 

2. Irritants of the respiratory system include the gases fluorine and chlorine, as well as the vapours of bromine and iodine.

3. When Halogen compounds are inhaled in small amounts, then their gases and vapours produce an unpleasant, pungent sensation that is followed by a sensation of suffocation, coughing, and a sensation of constriction in the chest. When these disorders cause damage to the lung tissue, the lungs may become overloaded with fluid, leading to the development of a condition known as pulmonary oedema, which has the potential to be lethal.

Conclusion

These reactive nonmetals have seven valence electrons, which makes them nonmetals. Halogens exhibit a wide range of physical properties when seen as a group. At ambient temperature, halogens can be found in a variety of states ranging from solid (I2) to liquid (Br2) to gaseous (F2 and Cl2). When they are pure elements, they combine to create diatomic molecules, which are held together by nonpolar covalent bonds.

The chemical properties have become more consistent. The electronegativities of the halogens are extremely high. Fluorine has the highest electronegativity of any element, and it is also the most reactive. The alkali metals and alkaline earths are extremely reactive with the halogens, resulting in the formation of stable ionic crystals.