A molecule It is the union of two or more atoms (of the same or different chemical elements) through chemical bonds, which form a stable set. For example: the water molecule is HtwoOR.
Molecules constitute the smallest division of a chemical substance without losing its physico-chemical properties or being denatured (that is, there is a non-atomic structural change of biomolecules such as proteins or nucleic acids, which leads to the loss of their biological functions). Molecules are generally electrically neutral (except the molecular ions, which are molecules with a positive or negative charge).
The interactions between the molecules of a substance they show its physical state: being close together, the interactions will be greater and it will be a solid; with mobility, it will be a liquid; and of being very dispersed and with a lot of mobility (although without separating completely) it will be a gas.
Examples of molecules
| Water: Htwo0 | Sucrose: C12H22OReleven |
| Hydrogen: Htwo | Propanal: C3H8OR |
| Oxygen: Otwo | Propenal: C3H6OR |
| Methane: CH4 | Para-aminobenzoic acid: C7H7NOtwo |
| Chlorine: Cltwo | Fluorine: Ftwo |
| Hydrochloric acid: HCl | Butane: C4H10 |
| Carbon dioxide: COtwo | Acetone: C3H6OR |
| Carbon monoxide: CO | Acetylsalicylic acid: C9H8OR4 |
| Lithium hydroxide: LiOH | Ethanoic acid: CtwoH4ORtwo |
| Bromine: Brtwo | Cellulose: (C6H10OR5) n |
| Iodine: Itwo | Dextrose: C6H12OR6 |
| Ammonium: NH4 | Trinitrotoluene: C7H5N3OR6 |
| Sulfuric acid: HtwoSW4 | Ribose: C5H10OR5 |
| Propane: C3H8 | Methanal: CHtwoOR |
| Sodium hydroxide: NaOH | Silver nitrate: AgNO3 |
| Sodium chloride: NaCl | Sodium cyanide: NaCN |
| Sulfur dioxide: SOtwo | Hydrobromic acid: HBr |
| Calcium sulfate: CaSO4 | Galactose: C6H12OR6 |
| Ethanol: CtwoH5Oh | Nitrous acid: HNOtwo |
| Phosphoric acid: H3PO4 | Silica: SiOtwo |
| Fullerene: C60 | Sodium thiopentate: CelevenH17NtwoORtwoSNa |
| Glucose: C6H12OR6 | Barbituric acid: C4H4NtwoOR3 |
| Sodium Acid Sulfate: NaHSO4 | Urea: CO (NH2)two |
| Boron trifluoride: BF3 | Ammonium Chloride: NH4Cl |
| Chloroform: CHCl3 | Ammonia: NH3 |
Types of molecules
Molecules can be classified according to different criteria:
According to its atomic composition:
- Discrete molecules. They are made up of a defined and specific number of atoms, either of different elements or of the same chemical element. They may be:
- Homonuclear molecules. They are composed of atoms of the same chemical element, for example, dinitrogen (Ntwo).
- Heteronuclear molecules. They are composed of atoms of different chemical elements, for example, carbon dioxide (COtwo).
- Macromolecules or polymers. Macromolecules are large molecular chains made up of simpler pieces called monomers, which are linked together to form more complex constructions. It is important to know that all polymers are macromolecules, but not all macromolecules are polymers.
The kind of traditional notation of the molecules is expressed in relation to the atomic content present, by means of the symbols of the periodic table to represent the elements involved and a subscript that expresses their numerical relationship within the molecule.
However, since molecules also have three-dimensional structural arrangements, a visual model that reflects the structure and not just the quantity of its elements is often used for their complete understanding.
According to the number of atoms that are integrated into its structure:
- Monatomic molecules. Made up of a single atom. For example: helium (He).
- Diatomic molecules. Made up of two atoms. For example: molecular oxygen (Otwo).
- Triatomic molecules. Made up of three atoms. For example: the water (HtwoOR).
- Tetraatomic molecules. Made up of four atoms. For example: ammonia (NH3), and so on.