Every time two atoms join together,they form a molecule. In fact, everything that surrounds us - and ourselves - consists of trillions of different types of molecules. The concept of a molecule was adopted in 1860 at the international congress of chemists in Karlsruhe. According to the accepted definition, a molecule is the smallest particle of a chemical substance that has all its chemical properties (solubility, taste, ability to join compounds, etc.). The introduction of the concept of a molecule pushed the development of physics, chemistry and other natural sciences. In a more general sense, a molecule is a particle made up of two or more atoms joined together by covalent bonds.
Atom is the smallest particle of a substance that has all its physical properties (color, hardness, density, etc.)
When atoms of various types of elements combinetogether, they form molecules called compounds. So, water consists of complex molecules consisting of 2 hydrogen atoms and 1 oxygen atom. That's why it is called H2O: a water molecule will always have 2 times more hydrogen atoms than oxygen atoms. There are just over 100 types of atoms, but the types of various substances are millions. The reason for this inequality lies in the fact that they are composed of various types of molecules.
It’s important to understand that molecules are not only composed ofdifferent types of atoms, but also from different ratios. As in the above example with water, a water molecule consists of two hydrogen atoms and one oxygen atom, which is written as H2O. Other examples are carbon dioxide (C02), ammonia (NH3) and sugar or glucose (C6H12O6). Some molecular formulas can be quite long and complex. Let's look at a sugar molecule:
- C6 - 6 carbon atoms
- H12 - 12 hydrogen atoms
- Oxygen atom O6 - 6
To make it, you need certain atoms ina certain amount. But molecules can be much larger. One molecule of vitamin C consists of 20 atoms (6 carbon atoms, 8 hydrogen atoms and 6 oxygen atoms - C6H8O6). If you take these 20 atoms of vitamin C and mix, connecting them together in a different order, you get a completely different molecule, which not only looks different, but also acts differently.
See also: Discovered new chemical compounds that can explain the emergence of life on Earth.
Some molecules, especially some proteins,contain hundreds or even thousands of atoms that join together in chains that can reach considerable lengths. Liquids containing such molecules sometimes behave strangely. For example, the liquid may continue to flow out of the flask from which some of it has been poured, even after the flask has been returned to the upright position.
- Oxygen gas is usually an O2 molecule, but it can also be O3, which we call ozone.
- Molecules can have various shapes. Some of them are long spirals, while others may take the form of a pyramid.
- An ideal diamond is the only molecule made up of carbon atoms.
- DNA is an extra-long molecule that has information that describes each person.
- 66% of the mass of the human body consists of oxygen atoms
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Molecules and compounds are held together by forces,called chemical bonds. There are four types of chemical bonds that hold most of the compounds together: covalent bonds, ionic bonds, hydrogen and metal bonds, however, covalent and ionic bonds are distinguished as the main ones, since they are bound to electrons. As you know, electrons revolve around atoms in shells. These shells want to be "full" of electrons. When they are not filled, they will try to connect with other atoms to get the right amount of electrons and fill their shells.
Covalent bonds Electrons are divided between atoms. This happens when it turns out that atoms share their electrons to fill their outer shells. In turn ionic bonds are formed when one electron is transferred to another. This happens when one atom gives an electron to another in order to form a balance and, therefore, a molecule or compound.
Read even more fascinating articles about how scientists split reality into atoms, read on our channel in Yandex.Zen. There are articles that are not on the site!
Also important is the fact thatmolecules are always in motion. In solids and liquids, they are very close to each other, and their movement can be compared with rapid vibration. In liquids, molecules can freely move among themselves, as if gliding. In a gas, the density of molecules is usually lower than in a liquid or solid of the same chemical compound, and therefore molecules move even more freely than in a liquid. For a particular compound in a given state (solid, liquid, or gaseous), the rate of molecular motion increases with increasing absolute temperature.