Chemistry. The compound is ..

Currently, thousands of different compounds are known to science. It is completely impossible to remember the formulas, names, and especially the properties of all of them. Scientists for centuries have been looking for ways to more conveniently classify chemical compounds. They managed to achieve considerable success in this. Consider the classification of simple and complex substances of chemistry, and also give them a brief description.

Classification of simple and complex compounds

All chemicals are divided into two large groups: simple and complex. Simple substances are those substances whose molecules include atoms of only one element. Complex substances are compounds that are already composed of several different elements. Both groups are divided, in turn, into subgroups that have a similar structure and properties.

Simple substances

As mentioned earlier, simple substances are built from atoms of one single element of the periodic system, so their names coincide with the names of these chemical elements of the table. In order not to confuse the definition of “chemical element” and “simple substance”, it must be understood that in the first case the element is considered as a component of the substance, and in the second - as the substance itself, which has its own properties. For example, there is oxygen in water as an element entering a substance, and there is oxygen as a substance that has its own characteristic, for example, the absence of smell and color.

Brief description of simple substances

Let us consider in more detail each subgroup of simple substances. There are four of them:

1. Metals, or metal compounds, are called elements of 1-3 groups (with the exception of boron) of the periodic table of D. I. Mendeleev, elements of side subgroups, octinoids and lantonoids. All metals are malleable and have a metallic luster, heat and electrical conductivity.
2. Non-metals, or non-metallic compounds, include all elements of 8-6 (except polonium) groups, as well as phosphorus, arsenic, carbon (from the 5th group), silicon, carbon (from the 4th group) and boron (from 3 th).
3. Amphigens, or amphoteric compounds, are compounds that are capable of exhibiting the properties of the first two subgroups described above. For example, zinc, aluminum and so on.
4. Elements of the 8th group are referred to noble (inert) gases: radon, xeon, krypton, argon, neon, helium. They are all inactive.

Classes of Complex Substances

For a clearer understanding of the differences between simple and complex substances, we will describe each subgroup of complex ones with proof of their belonging to this group of chemical compounds, i.e. we will name those several different elements that, being part of the compounds of this group, make them complex.

1. Oxides are substances that include two elements, one of which is oxygen. Therefore, these are complex substances. Oxides are: basic, acidic, amphoteric, double and non-salt forming (for example, CO, NO, N2O and so on).
2. Bases, or hydroxides, include substances that have an OH group (this is a hydroxyl group). So, in their compounds there is some element (mainly metals) + a hydroxy group consisting of hydrogen and oxygen. Thus, the composition of hydroxides includes three elements and this is a complex substance. They are: amphoteric, basic and acidic.
3. Acids include substances in which hydrogen ions are cations. Negative ions, or anions, of acids are called acid residues. It turns out that the composition of acids may include oxygen, hydrogen and another element (mainly non-metal). So these substances are also complex. Acids can be oxygen-containing or oxygen-free, monobasic or dibasic, tribasic, weak or strong.
4. And finally, salts are compounds consisting of a metal cation and an anion of an acid residue. Of course, this is a complex substance. Salts are: acidic, medium, basic, mixed and double.