All substances They are made up of atoms, which in turn can form ionic compounds, molecules (organic and inorganic), crystalline structures, and metallic compounds. The atom is the smallest unit that makes up matter and still retains the properties of the chemical element to which it belongs.
Molecules are stable, electrically neutral combinations of atoms. Much of the known matter is made up of molecules, which are extremely diverse in nature. Molecules can be simple or compound (also called chemical compounds).
Simple substances
The simple substances are those that are made up of only one chemical element, which can appear in unitary form (a single atom) or in several atoms of the same chemical element. The important thing is that the molecules of the substance cannot be broken down or separated into their different constituent elements using physical separation methods.
Examples of simple substances
The following list shows simple molecules:
| Bromine, Brtwo, Dibromo. | Iodine, Itwo, Diyodo. |
| Ozone, O3, Trioxygen. | Nitrogen, Ntwo, Dinitrogen. |
| Sodium, Na, Sodium. | Oxygen, Otwo, Dioxygen. |
| Sulfur, S8, Octasulfur. | Chlorine, Cltwo, Dichloro. |
| Chromium, Cr, Chromium. | Potassium, K, Potassium. |
| Hydrogen, Htwo, Dihydrogen. | Gold, Au, Gold. |
| Fluorine, Ftwo, Difluorine. | White phosphorus, P4, Tetraphosphorus. |
| Iron, Fe, Iron. | |
Compound substances
The compound substances They are those that are formed by at least two atoms of two or more chemical elements, chemically united in defined proportions. This means that compound substances can be decomposed into simple substances through certain chemical reactions, which makes sense and is to be expected: elements are frequently in constant interaction with each other.
Most substances are compound, and can be classified in two ways:
Depending on the number of elements in your formula, they can be:
- Binary substances. They are made up of two chemical elements. For example: Water (HtwoOr, hydrogen and oxygen).
- Ternary substances. They are made up of three chemical elements. For example: nitric acid (HNO3, hydrogen, nitrogen and oxygen).
- Quaternary substances. They are made up of four chemical elements. For example: sodium hydrogen sulphite (NaHSO3, sodium, hydrogen, sulfur and oxygen).
According to their structure (fundamental elements that constitute them), they can be:
- Organic compounds. Its structure is based on carbon-carbon and carbon-hydrogen bonds, but they can also have elements such as oxygen, sulfur, nitrogen and phosphorus. For example: ethanol (CH3CHtwoOH).
- Inorganic compounds. They do not have their backbone based on carbon, which is not to say that they cannot have carbon. For example: carbon dioxide (COtwo).
Examples of compound substances
- Ethyl alcohol or ethanol (CH3CHtwoOH or CtwoH6O, carbon, hydrogen and oxygen)
- Sugar (Sucrose, C12H22OReleven, carbon, hydrogen and oxygen)
- Acetone (CH3Car3 or C3H6O, carbon, hydrogen and oxygen)
- Carbon dioxide (COtwo, carbon and oxygen)
- Calcium sulfide (CaS, sulfur and calcium)
- Sodium bicarbonate (NaHCO3, sodium, carbon, hydrogen and oxygen)
- Hydrochloric acid (HCl, hydrogen and chlorine)
- Sulfuric acid (HtwoSW4, hydrogen, sulfur and oxygen)
- Water (HtwoOr, hydrogen and oxygen)
- Chloroform (CHCl3, carbon, chlorine and hydrogen)
- Sodium oxide (NatwoO, oxygen and sodium)
- Salt (NaCl, sodium and chlorine)
- Ammonia (NH3, nitrogen and hydrogen)
- Carbon monoxide (CO, oxygen and carbon)
- Potassium bromide (KBr, bromine and potassium)
There are usually three types of nomenclature to call both types of molecules (simple and compound):
- Traditional nomenclature. It uses certain prefixes and suffixes that depend on the valence of the chemical elements that make up the substance.
- Systematic nomenclature. Use Greek prefixes to indicate the number of atoms of the chemical elements involved.
- Stock nomenclature. The name of the compound is written putting at the end in parentheses and in Roman numerals the oxidation number of the chemical element that is named putting its real name.
Many times, compound molecules give rise to the generation of substances that have a specific name in themselves, thus opening a new nomenclature.