In the periodic table, non-metals are located in the upper right triangle, and when the group number decreases, their number in it also falls. In the seventh group (halogens), all elements are non-metals. These are fluorine, chlorine, bromine, iodine and astatine. Although we do not consider the latter, since, firstly, it is radioactive in itself, it occurs in the earth's crust only as an intermediate decay product of uranium, and its compound HAt (hydrogen astatide), obtained in the laboratory, is extremely unstable and behaves in solution not like other hydrogen halides. In the sixth group there are already fewer non-metals (oxygen, sulfur, selenium and tellurium, which is a metalloid), in the fifth there are three (nitrogen, phosphorus and arsenic), in the fourth - two (carbon and silicon), and in the third there is a lone boron. Hydrogen compounds of nonmetals of the same group have similar chemical properties.
Halogens
Hydrohalides are the most important halogen compounds. According to their properties, these are anoxic acids, dissociating in water into a halogen anion and a hydrogen cation. All of them are highly soluble. The chemical bond between the atoms in the molecule is covalent, the electron pair is shifted towards the halogen as more electronegative. Since the higher the periodic table, the greater the electronegativity of the atom, withAs the period decreases, the covalent bond becomes more and more polar. Hydrogen carries a greater partial positive charge, in solution it is easier to break away from halogen, that is, the compound dissociates more completely and more successfully, and the strength of acids increases in the series from iodine to chlorine. We did not say about fluorine, because in its case the exact opposite is observed: hydrofluoric (hydrofluoric acid) is weak and dissociates very poorly in solutions. This is explained by such a phenomenon as hydrogen bonds: hydrogen is introduced into the electron shell of the fluorine atom of a "foreign" molecule, and an intermolecular bond occurs that does not allow the compound to dissociate as expected.
This is clearly confirmed by the graph with the boiling points of various hydrogen compounds of non-metals: compounds of elements of the first period - nitrogen, oxygen and fluorine - that have hydrogen bonds are distinguished from them.
Oxygen group
The hydrogen compound of oxygen is obviously water. There is nothing remarkable about it, except that oxygen in this compound, unlike sulfur, selenium and tellurium in similar ones, is in sp3-hybridization - this is evidenced by the bond angle between the two bonds with hydrogen. It is assumed that this is not observed for the remaining elements of group 6 due to the large difference in the energy characteristics of the outer levels (hydrogen has 1s, oxygen has 2s, 2p, while the rest have 3, 4 and 5, respectively).
Hydrogen sulfide is released during protein decay, therefore it manifests itself with the smell of rotten eggs, poisonous. It occurs in nature in the form of volcanic gas, is released by living organisms during the processes already mentioned (rotting). In chemistry it is used as a strong reducing agent. When volcanoes erupt, it mixes with sulfur dioxide to form volcanic sulfur.
Hydrogen selenide and hydrogen telluride are also gases. Terribly poisonous and have an even more disgusting smell than hydrogen sulfide. As the period increases, the reducing properties increase, and so does the strength of aqueous solutions of acids.
Nitrogen group
Ammonia is one of the most famous hydrogen compounds of non-metals. Nitrogen here is also in sp3-hybridization, retaining one unshared electron pair, due to which it then forms various ionic compounds. It has strong restorative properties. It is known for its good ability (due to the same lone electron pair) to the formation of complexes, acting as a ligand. Ammonia complexes of copper, zinc, iron, cob alt, nickel, silver, gold and much more are known.
Phosphine - a hydrogen compound of phosphorus - has even stronger reducing properties. Extremely toxic, ignites spontaneously in air. Has a dimer present in the mixture in small amounts.
Arsine - arsenic hydrogen. Toxic, like all arsenic compounds. It has a characteristic garlic smell, which appears due to the oxidation of a part of the substance.
Carbon and silicon
Methane - hydrogenthe compound of carbon is the starting point in the boundless space of organic chemistry. This is exactly what happened to carbon, because it can form long stable chains with carbon-carbon bonds. For the purposes of this article, it is worth saying that the carbon atom also has sp3 hybridization here. The main reaction of methane is combustion, during which a large amount of heat is released, which is why methane (natural gas) is used as a fuel.
Silane is a similar silicon compound. It ignites spontaneously in air and burns out. It is noteworthy that it is also capable of forming carbon-like chains: for example, disilane and trisilane are known. The problem is that the silicon-silicon bond is much less stable and the chains break easily.
Bor
With boron everything is very interesting. The fact is that its simplest hydrogen compound - borane - is unstable and dimerizes, forming diborane. Diborane ignites spontaneously in air, but is itself stable, as are some subsequent boranes containing up to 20 boron atoms in a chain - in this they have advanced further than silanes with a maximum number of 8 atoms. All boranes are poisonous, including nerve agents.
Molecular formulas of hydrogen compounds of non-metals and metals are written in the same way, but they differ in structure: metal hydrides have an ionic structure, non-metals have a covalent structure.
