What is an inorganic compound?
Concept, Properties, Types and Examples
We explain what an inorganic compound is and its properties. In addition, the types of inorganic compounds that exist and examples.
Inorganic compounds are less abundant than organic ones.
Unlike the organic ones, typical of the chemistry of life, inorganic compounds are those whose composition does not revolve around carbon and hydrogen, but involves various types of elements, almost all of which are known from the periodic table.
These compounds are formed through physical reactions and phenomena present in nature, such as solar energy, the action of electricity or heat, etc., which allow the creation of various substances. The atoms and their molecules are usually bound together by ionic or covalent bonds.
Despite the variety of elements available, inorganic compounds are far less abundant and diverse on our planet than organic ones. Similarly, they have a different form of nomenclature and are often involved in different processes.
Inorganic compounds can be: oxides, hydrides, salts, hydroxides and oxacids.
What properties do they have?
Inorganic compounds have high melting and boiling points.
Inorganic substances can differ greatly from each other, so their properties are not always common or universal. Broadly speaking, however, it is about:
- Good conductors of heat and electricity.
- The ionic bond (electrovalent) predominates in them.
- They have high melting and boiling points.
- When they are solid, they tend to present hardness and fragility.
- They are usually organized in crystals, when solid, due to the lack of mobility between their ions.
Types of inorganic compounds
Hydroxides result from the union of a metal with a hydroxyl group.
Inorganic compounds present a great variety of structures, but they can be classified according to the number of elements that intervene in each compound, in the following way:
Binary compounds. Those consisting of only two chemical elements. Such as:
- Oxides. Product of the union of oxygen (O2) with some metallic element (basic oxides) or non-metallic element (acid oxides) of the periodic table. For example: chlorine (VII) oxide: Cl2O7 – ferrous oxide: FeO.
- Peroxides. Peroxides are joints of the peroxide group (O2-2) with a metallic element. For example: gold (III) peroxide: Au2(O2)3 – lithium peroxide: Li2O2.
- Hydrides. Hydrides are composed by joining a hydride anion (H-) of negative electrical charge with any metallic cation (positive charge). For example: Lithium hydride: LiH – Beryllium hydride: BeH2.
- Binary salts. These are ions, i.e. sets of electrically charged atoms, either cations (+) or anions (-). These types of ions are also salts. For example: calcium chloride: CaCl2 – iron bromide: FeBr3.
Ternary compounds. Those involving three chemical elements. Such as:
- Hydroxides. Resulting from the union of a metallic element with a hydroxyl group (OH-). They are commonly called “bases” or “alkalis. For example: sodium hydroxide: NaOH – germanium hydroxide (IV): Ge(OH)4.
- Oxacids. Acids that arise from the reaction between an anhydride (a non-metal oxide) and water. Its formula always depends on a HaAbOc pattern, where A is a transition metal or a non-metal. For example: sulphuric acid: H2SO4 – carbonic acid: H2CO3.
Examples of inorganic compounds
Ammonia is an inorganic molecule composed of hydrogen and nitrogen.
Some commonly used inorganic compounds are:
- Water (H2O). Despite being so abundant in the world and being indispensable for life, water is an inorganic substance, liquid at normal and solid temperature when cooled below 0° C, capable of becoming gas (vapour) when carried at 100 °C.
- Sodium chloride (NaCl). The common salt that we use to eat, is composed of an atom of sodium and another of chlorine, and it is abundantly in the terrestrial crust, mainly dissolved in the waters of the sea.
- Ammonia (NH3). An inorganic molecule composed of hydrogen and nitrogen, which is excreted along with others (such as urea) by the metabolic systems of various living beings. It usually comes in a gaseous form, and has a characteristic unpleasant smell.
- Carbon dioxide (CO2). A gas composed of carbon and oxygen that is extremely abundant in our atmosphere, as various metabolic processes throw it as a by-product: animal respiration, fermentation, and so on. It is, at the same time, the elemental input to carry out the photosynthesis of the plants.
Calcium oxide (CaO). Also called “quicklime”, it is widely used in construction and is obtained by calcination of limestone rocks or dolomites, rich in mineral calcium sources.