Halogens are pronounced non-metals. These include fluorine, astatine, iodine, bromine, chlorine, and an artificial element called ununseptium (tennessine). These substances have a wide range of chemical functions and are worth talking about in more detail.
High oxidative activity
This is the first pronounced property to be mentioned. All halogens have a high oxidative activity, but fluorine is the most active. Further descending: chlorine, bromine, iodine, astatine, ununseptium. But fluorine reacts with all metals without exception. Moreover, most of them, being in the atmosphere of this element, self-ignite, and this process is accompanied by the release of a large amount of heat.
If fluorine is not heated, then in this case it will react with many non-metal substances. For example, with sulfur, carbon, silicon, phosphorus. Reactions are obtainedhighly exothermic, and may be accompanied by an explosion.
It is also worth noting that fluorine, when heated, oxidizes all other halogens. The scheme is as follows: Hal2 + F2=2HalF. And here Hal is chlorine, bromine and iodine. Moreover, in such compounds, the degree of their oxidation is +1.
And one more chemical property of halogen-fluorine is its reaction with heavy inert gases under the influence of irradiation. They are also called noble. These gases include helium, neon, argon, krypton, xenon, radon, and the recently discovered oganesson.
Interaction with complex substances
This is another chemical property of halogens. Complex substances, as is known, include compounds consisting of two or more elements. The same fluorine manifests itself in such reactions very vigorously. They are accompanied by an explosion. But, for example, this is how its reaction with water looks like in the form of a formula: 2F2 + 2H2O → 4HF +O 2.
Chlorine is also reactive, although its activity is less than that of fluorine. But it reacts with all simple substances except noble gases, nitrogen and oxygen. Here is one example: Si + 2Cl2 → SiCl4 + 662kJ.
But the reaction of chlorine with hydrogen is especially interesting. If there is no proper lighting and temperature, then nothing happens between them. But if you increase the brightness and heat them up, then an explosion will occur, moreover, by a chain mechanism. The reaction proceeds under the influence of photons, quanta of electromagnetic radiation, whichdissociates Cl2 molecules into atoms. Next, a whole chain of reactions occurs, and in each of them a particle is obtained that initiates the beginning of the next stage.
Bromine
As you can see, most of the talk about fluorine and a little less about chlorine. This is because the chemical properties of halogens consistently decrease from fluorine to astatine.
Bromine is a kind of middle in their series. It is more soluble in water than other halogens. The resulting solution is known as bromine water, a powerful substance that can oxidize nickel, iron, chromium, cob alt and manganese.
If we talk about the chemical properties of halogen, then it is worth mentioning that in terms of activity it occupies an intermediate position between the notorious chlorine and iodine. By the way, when it reacts with iodide solutions, free iodine is released. It looks like this: Br2 + 2Kl → I2 + 2KBr.
Also, bromine can react with non-metals (tellurium and selenium), and in the liquid state it interacts with gold, resulting in the formation of tribromide AuBr3. He is also able to join organic molecules with a triple bond. If heated in the presence of a catalyst, it can react with benzene to form bromobenzene C6H5Br, which is called a substitution reaction.
Iodine
The next most active chemical properties of halogens in the table is iodine. Its peculiarity lies in the fact that it forms a number of different acids. These include:
- Iodine. Colorless liquid with a pungent odor. A strong acid that is a powerful reducing agent.
- Iodine. Unstable, can only exist in highly dilute solutions.
- Iodine. The characteristics are the same as the previous one. Forms iodite s alts.
- Iodine. Crystalline colorless substance with a vitreous luster. Soluble in water, prone to polymerization. Has oxidizing properties.
- Iodine. Hygroscopic crystalline substance. Used in analytical chemistry as an oxidizing agent.
The general chemical properties of halogen-iodine include high activity. Although it is less than that of chlorine with bromine, and even more so is not comparable with fluorine. The most famous reaction is the interaction of iodine with starch, which results in a blue color of the latter.
Astatine
It is also worth saying a few words about it in continuation of the discussion of the general characteristics of halogens. The physical and chemical properties of astatine are close to those of the notorious iodine and polonium (a radioactive element). Here is his brief description:
- Produces an insoluble AgAt s alt, like all halogens.
- Can be oxidized to At, like iodine.
- Forms compounds with metals, showing an oxidation state of -1. Like all halogens though.
- Reacts with iodine and bromine to form interhalogen compounds. Astatine iodide and bromide, to be precise (AtI and AtBr).
- Dissolves in nitrogen and hydrochloricacids.
- If you act on it with hydrogen, then gaseous hydrogen astatide is formed - an unstable gaseous acid.
- Like all halogens, it can replace hydrogen in a methane molecule.
- Has characteristic alpha radiation. By its presence, the presence of astatine is determined.
By the way, the introduction of astatine in the form of a solution into the human body treats the thyroid gland. In radiotherapy, this element is actively used.
Tennesin
And he needs to pay attention, since we are talking about the chemical properties of halogens. There are not very many known compounds with tennessine, since so far its exact characteristics remain the subject of discussion, since it was included in the table only in 2014.
Most likely it is a semi-metal. It shows almost no oxidizing power, thus being the weakest of the halogens, since its electrons are too far from the nucleus. But it is highly likely that tennessine will be the halogen, the reducing property of which will be higher than the oxidizing one.
Experimentally carried out reaction with hydrogen. TsH is the simplest connection. The resulting tennessine hydrogen continues most of the trends for hydrogen halides.
Physical properties
They should be briefly mentioned. So:
- Fluorine is a poisonous light yellow gas with a pungent odor.
- Chlorine is a light green gas. It also has a strong odor and is more poisonous than fluorine.
- Bromine is a red-brown heavy liquid. Histhe vapors are highly toxic.
- Iodine is a dark gray solid with a metallic sheen.
- Astatine is a blue-black solid. Looks like iodine.
Getting halogens
This is the last thing. The chemical properties and production of halogens are directly related. The first conditions the second. Here are some ways to get these substances:
- Through the electrolysis of melts or solutions of halides - their compounds with other elements or radicals.
- Through the interaction of their solid s alts and concentrated sulfuric acid. But this only applies to HF and HCl.
- HBr and HI can be obtained by hydrolysis of phosphorus halides.
- Oxidation of hydrohalic acids.
- HClO is obtained by hydrolysis in aqueous solutions of chlorine.
- HOBr is formed by the interaction of water and halogen.
But in general there are many more ways to get, these are just examples. After all, halogens are widely used in industry. Fluorine is used to produce lubricants, chlorine is used for bleaching and disinfection, bromine is used in medicine and the production of photographic materials, and iodine is not even worth talking about.
