Currently, thousands of different compounds are known to science. It is absolutely impossible to remember the formulas, names, and even more so the properties of all of them. Scientists have been looking for ways to more conveniently classify chemical compounds for centuries. They have achieved great 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 substances whose molecules contain atoms of only one element. Complex substances are compounds that already consist of several different elements. Both groups are divided, in turn, into subgroups with similar structure and properties.
|Simple substance||Complex substance|
As mentioned earlier, simple substances are built from atoms of a 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 definitions of "chemical element" and "simple substance", one must understand 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 water oxygen as an element that enters the substance, and there is oxygen as a substance that has its own characteristics, such as the absence of smell and color.
Brief characteristics of simple substances
Let's consider in more detail each subgroup of simple substances. There are four of them:
- Metals, or metal compounds, are the elements of groups 1-3 (with the exception of boron) of the periodic table of D. I. Mendeleev, elements of secondary subgroups, octinoids and lantonoids. All metals are malleable and have a metallic luster, thermal and electrical conductivity.
- Non-metals, or non-metallic compounds, include all elements of groups 8-6 (with the exception of polonium), as well as phosphorus, arsenic, carbon (from the 5th group), silicon, carbon (from the 4th group) and boron (from 3rd).
- Amphigenes, 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.
- Noble (inert) gases include elements of the 8th group: 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 substances with proof of their belonging to this group of chemical compounds, that is, we will name those several different elements that, being part of the compounds of this group, make them complex.
- Oxides are substances that include two elements, one of which is oxygen. Therefore, they are complex substances. Oxides are: basic, acidic, amphoteric, binary and non-s alt-forming (for example, CO, NO, N2O, and so on).
- Bases, or hydroxides, include substances that have an OH group (this is a hydroxyl group). This means that in their compounds there is some element (mainly metals) + a hydroxo 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.
- To acids are substances in which hydrogen ions are cations. The negative ions, or anions, of acids are called acid residues. It turns out that the composition of acids can include oxygen, hydrogen, and another element (mostly a non-metal). Hence, these substances are also complex. Acids can be oxygenated or anoxic, monobasic or dibasic or tribasic, weak or strong.
- And finally, s alts are compounds consisting of a metal cation and an anion of an acid residue.Of course, and this is a complex substance. S alts are: sour, medium, basic, mixed and double.