According to its origin, it is possible to classify all known matter into natural substances and artificial substances. The term “substance” means that they are substances with a fixed and defined chemical composition. Substances are made up of atoms or molecules, and cannot be separated using physical separation methods (they are not mixtures).
- Natural substances. They are those that are commonly found in nature, whether organic or not, and whose obtaining involves only the effort necessary to extract and collect the material, as in the case of minerals in the earth’s crust. They are substances originated in nature without the intervention of the human being or another living being. For instance: wool, charcoal, sea salt.
- Artificial or synthetic substances. They are those created or made by man in factories, metallurgy or laboratories, whether they are new and non-existent species, or synthetic replicas of natural compounds, such as resins and synthetic fabrics. For instance: glass, plastic, trans fat.
Other ways to classify substances
Substances can also be classified into:
- Simple substances and compound substances. The former are made up of atoms of a single chemical element (for example, molecular oxygen, O2), while the latter are made up of atoms of different chemical elements (for example, water, H2OR).
- Organic substances and inorganic substances. According to the atoms on which its composition is based: all organic substances are based mainly on carbon, while inorganic substances can present any combination of elements, including carbon, but without this constituting their primary structure.
Examples of natural substances
- Water. It is the most abundant inorganic substance on the planet, essential for the emergence and maintenance of life. Its simple molecule, with two atoms of hydrogen and one of oxygen, is the product and by-product of numerous chemical reactions and is abundant in gaseous form in our atmosphere. It is estimated that 70% of the planet’s surface is water between solid and liquid.
- Wool. It is a natural fiber secreted by the animals of the goat family and some camelids, which it serves as shelter and defense against the cold. This fiber is usable for fabrics, so it is sheared and processed.
- Rubber. It is an elastic polymer, with waterproof and resistant properties, secreted by the tree with the same name and other tropical trees, from whose trunks it is extracted in the form of a milky liquid. It has been used since ancient times to make pots and other containers and in modern times for thousands of industrial applications, such as automobile tires. Today, however, it is produced synthetically.
- Wood. Composed of cellulose and lignin, wood is found in the trunk of trees, and grows year after year through a system of concentric rings. This substance is very usable by man given its characteristics of hardness, elasticity and combustibility, both for the carving of tools and utensils, the construction of buildings and even as biomass for burning in ovens and chimneys.
- Iron. It is a metallic element, resistant, ductile and magnetic, very prone to oxidation, which usually occurs in nature in the form of oxides and mineral compounds. Iron in its pure state is rare, but it can be obtained from its natural sources and used in metallurgy to make alloys.
- Coal. One of the forms of carbon in nature, along with graphite and diamonds, is carbon. In all three cases they are agglomerations of atoms of this element, but arranged in a very different way, so that some are more resistant than others and have different physical properties.
- Sea salt. Also called sodium chloride (NaCl), common salt is an inorganic substance that is produced by the union of a sodium atom and a chlorine atom, in a solid form of whitish crystals. It can be easily obtained by evaporating sea water, since the liquid disappears and the saline crystals remain.
- Helium. Like many of the noble (inert) gases, this monatomic gas has a very low reactivity despite being very frequent in nature, either as a member of our atmosphere (from where it can be extracted) or as a by-product of the fusion of hydrogen in the bosom of the stars.
- Nacre. It is a hard, iridescent and white substance that is composed of crystallized calcium carbonate, organic matter and water, in a unique combination that many marine mollusks can produce inside their shells, to repair possible damage and to preserve their refuge. .
- Glucose. The sugar present in fruits, honey and in the blood of animals (including man) is a monosaccharide of molecular formula C, whose importance in animal metabolism is capital, since it constitutes its main form of energy reserve at the same time than an important piece in the construction of more complex compounds.
Examples of artificial substances
- Aspirin. Acetylsalicylic acid, commonly known as aspirin, is a compound derived from the bark of the white willow tree, which today is completely synthesized in high-purity ranges in laboratories. It is a non-steroidal anti-inflammatory and analgesic, considered the most widely used medicine in the world.
- Artificial glass. It is a translucent, hard and brittle substance that is obtained through the smelting of a mixture of silica and some carbonates, and is used to make containers, window coverings or automotive glass. It is one of the most manufactured compounds in the world, since its domestic consumption is very high.
- Uranium-233. It is one of the least stable isotopes of uranium, an element of our planet that can be used in nuclear-type reactions to obtain energy. In fact, the atomic bomb dropped on Japan contained variants of this metal. However, the variant 233U does not exist in nature but is produced from natural thorium.
- Cement. It is the product of a mixture of calcined and ground clay and limestone, to which gypsum is added and later gravel and sand. This powder is widely used in construction and civil engineering, because when adding water to it, a uniform, malleable and plastic paste is formed that hardens to form stone-hard concrete or cement.
- Plastic. It is a synthetic material obtained by polymerization processes of carbon chains of organic compounds derived from oil (hydrocarbons). It is perhaps the most produced synthetic material in the world, with countless applications in the areas of engineering, commerce and even medicine.
- Ferrofluid. These substances were synthesized in the second half of the 20th century and are fluids that, in the presence of a magnetic field, proceed to polarize. They have an extreme susceptibility to magnetism (“superparamagnetic”), since they are made of magnetic nanoparticles contained in a liquid that does not allow them to agglomerate. They are the closest approximation that exists to a magnetic liquid as such.
- Airgel. Also called “frozen smoke”, it is a colloidal material similar to a gel, in which the liquid is exchanged for a gas, thus obtaining a very light, low-density, porous solid, endowed with an enormous capacity for thermal insulation. It was created in 1931 and since then it has been produced from numerous substances, such as silica, zirconium or alumina.
- Carbon nanotubes. It is a state-of-the-art nanomaterial, highly hydrophobic, obtained by artificially modifying the proportions of carbon to achieve allotropic forms (such as diamond or fullerene), this time as a sheet of graphene rolled up on itself. They are tiny and possess surprising characteristics: they are superconducting of electricity and can withstand 100 times more stress than steel.
- Perfluorocarbons. If the hydrogen atoms of a hydrocarbon are replaced by fluorine atoms, a perfluorocarbon is obtained, a substance whose properties are controllable from the length of the carbon chains that compose it, and it can be gaseous or liquid. This makes it extremely useful for medicine (as a filler in eye operations) or powerful refrigerant.
- Fats trans. Although they can be found in small amounts in the milk or body fat of animals, most of the trans fats that we consume in many industrially processed foods are the result of the hydrogenation of fats, such as in fast food and processed foods or synthetic dairy such as margarine. These fats are particularly harmful to the body as they lower good cholesterol and increase bad cholesterol.