Halogens are pronounced non-metals. These include fluorine, astatine, iodine, bromine, chlorine, and an artificial element called ununseptium (tennessin). These substances have a wide range of chemical functions, and it is worth telling more about them.
High oxidative activity
This is the first pronounced property that needs to be said. All halogens have high oxidative activity, but most of all fluorine. Further downward: 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. The reactions are highly exothermic, and may be accompanied by an explosion.
It is also worth noting that when heated, fluorine oxidizes all other halogens. The scheme is: Hal 2 + F 2 = 2 HalF. And here Hal is chlorine, bromine and iodine. Moreover, in such compounds the degree of oxidation is +1.
And another chemical property of fluorine halogen is its reaction with heavy inert gases under the influence of radiation. They are also called noble. Such gases include helium, neon, argon, krypton, xenon, radon, and the recently discovered Oganeson.
Interaction with complex substances
This is another chemical property of halogens. Complex substances, as you know, include compounds consisting of two or more elements. The same fluorine manifests itself very energetically in such reactions. They are accompanied by an explosion. But, for example, this is how his reaction with water looks like a formula: 2F 2 + 2H 2 O → 4HF + O 2 .
Chlorine is also reactive, although its activity is less than that of fluorine. But it reacts with all simple substances, except for noble gases, nitrogen and oxygen. Here is one example: Si + 2Cl 2 → SiCl 4 + 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, then an explosion will occur, moreover, by a chain mechanism. The reaction proceeds under the influence of photons, quanta of electromagnetic radiation, which dissociates Cl 2 molecules into atoms. A whole chain of reactions follows, and in each of them a particle is obtained that initiates the beginning of the next stage.
Bromine
As you can already see, the most said about fluoride and a little less about chlorine. This is because the chemical properties of halogens are gradually decreasing from fluorine to astatine.
Bromine is a middle ground among them. It is better than other halogens in water. The resulting solution is known as bromine water - a powerful substance that can oxidize nickel, iron, chromium, cobalt and manganese.
If we talk about the chemical properties of halogen, it is worth mentioning that in 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: Br 2 + 2Kl → I 2 + 2KBr.
Also, bromine can react with non-metals (tellurium and selenium), and in the liquid state it interacts with gold, as a result of which AuBr 3 tribromide is formed. He is also able to attach to organic molecules with a triple bond. If heated in the presence of a catalyst, it will be able to interact with benzene to form C 6 H 5 Br bromobenzene, which is called a substitution reaction.
Iodine
The next most active chemical property of halogens in the table is iodine. Its peculiarity lies in the fact that it forms a number of different acids. These include:
- Hydrogen iodide. Colorless liquid with a pungent odor. Strong acid, a powerful reducing agent.
- Iodovistataya. Unstable, can exist only in highly diluted solutions.
- Iodine. The characteristics are the same as the previous one. Forms iodite salts.
- Iodine. A crystalline colorless substance with a glass sheen. It is soluble in water, prone to polymerization. It has oxidizing properties.
- Iodine. Hygroscopic crystalline substance. It is 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 it is not comparable with fluorine. The most famous reaction is the interaction of iodine with starch, the result of which is the blue staining of the latter.
Astatine
A couple of words should be said about him in the course of 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:
- Forms an insoluble salt of AgAt, like all halogens.
- It can oxidize to a state of At, like iodine.
- It forms compounds with metals, exhibiting an oxidation state of -1. Like all halogens, however.
- Reacts with iodine and bromine, forming interhalogen compounds. Astatine iodide and bromide, to be more precise (AtI and AtBr).
- It is soluble in nitric and hydrochloric acids.
- If you act on it with hydrogen, then gaseous astatine hydrogen is formed - fragile gaseous acid.
- Like all halogens, it can replace hydrogen in a methane molecule.
- It has a characteristic alpha radiation. The presence of astatine is determined by its presence.
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 used actively.
Tennesin
And he needs to pay attention, since we are talking about the chemical properties of halogens. There are not very many compounds with tennesin, since so far its exact characteristics remain the subject of discussion, because it was included in the table only in 2014.
Most likely, this is a semimetal. It exhibits almost no oxidative ability, thus being the weakest of halogens, since its electrons are too far from the nucleus. But it is highly likely that tennessin will be that halogen, the reducing property of which will be higher than the oxidizing one.
The reaction with hydrogen was carried out experimentally. TsH is the simplest connection. The resulting tennesin hydrogen continues most of the trends for hydrogen halides.
Physical properties
They should be discussed briefly. So:
- Fluoride is a poisonous light yellow gas with a pungent odor.
- Chlorine is a light green gas. It also has a pungent odor and is more toxic than fluoride.
- Bromine is a reddish-brown heavy liquid. His fumes are highly toxic.
- Iodine is a dark gray solid with a metallic sheen.
- Astatine is a blue-black solid. It looks like iodine.
Halogen production
About this - in the end. Chemical properties and halogen production are directly related. The first determines the second. Here are the ways you can get these substances:
- By electrolysis of melts or solutions of halides - their compounds with other elements or radicals.
- By the interaction of their solid salts and concentrated sulfuric acid. But this applies only 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 due to the interaction of water and halogen.
But in general, there are much 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 needed.