What are inorganic compounds?

The inorganic compounds are those which are formed by the combination of a metal element (calcium, sodium, iron, etc.) with a nonmetal element (chlorine, oxygen, carbon, etc.).

The ionic bond is the main link type inorganic compounds: an electrical attraction between the metal ion of the positively charged (+) and ion nonmetal negatively charged (-). This interaction is very strong and explains many of the properties of inorganic compounds, such as having high boiling and melting points.

On the other hand, inorganic compounds can also result from the combination of two nonmetal elements that share a pair of electrons, forming the so-called covalent bond. An example of this is water (H 2 O).

The main difference between organic and inorganic compounds is that organics always contain the element carbon, while most inorganic compounds do not. Another main characteristic of inorganic compounds is that they do not have carbon-hydrogen bonds.

Examples of inorganic compounds are water, carbon dioxide, table salt, or hydrochloric acid.

Properties of inorganic compounds

Despite the great diversity of inorganic compounds, most of them share a set of common properties, the following being possible:

Ionic bond

The chemical elements of inorganic compounds are united by an ionic bond that consists of an electrical attraction between particles with opposite electrical charges; that is, with positive and negative charges.

Electric conductors

Inorganic compounds in aqueous solution are good conductors of electricity, because they dissociate into ions when dissolved in water.

Ions are electrically charged particles, and therefore they are good conductors of electricity.

Melting and boiling points

Inorganic compounds have high melting and boiling points.

This is due to the fact that to change the physical state, the ionic bonds with high energy content must be broken, which is why a high energy supply is necessary.

Inorganic compounds are generally soluble in water.

Water molecules are electric dipoles, that is, they have a positive and negative electric charge at their ends, so they can interact electrically with ions, electrically charged particles. Water interacts with ions using these poles, which favors the solubility of inorganic compounds.

Solid state or phase

Inorganic compounds are usually solid due to the ionic bonds that exist between the chemical elements that form them.

A consequence of this is that the electrical interactions end up organizing the ions in crystalline networks, and therefore, in crystalline solids.

Crystal hardness

The crystals of inorganic compounds have great hardness due to the ionic bonds that are present in them.

However, when they are deformed, elements with the same electrical charge come together, which can cause repulsive forces capable of breaking the crystalline structure.

Low volatility

Inorganic compounds are generally low volatile and non-combustible.

The explanation is that these compounds do not usually undergo evaporation at room temperature, and are also made up of chemical elements that do not burn easily.

Classification: types of inorganic compounds

The types of inorganic compounds are usually established based on the number of different chemical elements present in them. Following this criterion, inorganic compounds are classified into binary, ternary and quaternary.

Binary inorganic compounds

They are compounds formed by the union of two different chemical elements, among them are: oxides, peroxides, hydrides, hydracids, hydroxides and binary salts.


They are formed by the combination of oxygen (O 2 ) with another chemical element. They are classified as basic oxides and acid oxides. However, there are other very characteristic oxides, among which stand out, for example, inorganic peroxides.

  • Basic oxides : they are formed by the combination of a metal element with oxygen. These compounds give rise to hydroxides. For example: ferric oxide (Fe 2 O 3 ).
  • Acidic oxides : are formed by the union of a non-metal element with oxygen. They are characterized by originating acids. For example: bromic oxide (Br 2 O 5 ).
  • Inorganic peroxides : they have an oxygen-oxygen bond in their structure that can combine with hydrogen to produce hydrogen peroxide (H 2 O 2 ), or it can combine with a metal. For example: sodium peroxide (Na 2 O 2 ).


They can be metal hydrides and non-metal hydrides:

  • Metal hydrides : are formed by the bonding of hydrogen with valence or oxidation state -1 with a metal. For example: potassium hydride (KH).
  • Non-metallic hydrides : chemical compounds originated by the combination of hydrogen with valence +1, with a non-metal element using its lower valence. They are gaseous and when they dissolve in water they originate acids. For example: hydrogen chloride (HCl).

Acids (hydracids)

They result from the combination, generally, in the gaseous phase of hydrogen with a non-metal element. For example: hydroiodic acid (HI).

Binary salts

They are formed by the union of a metal element, with a positive charge, and a non-metal element, negatively charged, thus establishing an ionic bond between them. For example: calcium chloride (CaCl 2 ).

Ternary inorganic compounds

Three different chemical elements are present in them, forming part of this group: hydroxides, oxacids and ternary salts.


They originate from the reaction of a basic oxide with water, presenting hydroxyl groups (OH). For example: calcium hydroxide [(Ca (OH) 2 ].


They are formed by the reaction of an acid oxide with water. These acids have oxygen. For example: nitric acid (HNO 3 ).

Ternary salts

They result from the neutralization reaction of an oxacid with a hydroxide, forming the ternary salt and water. For example: sodium carbonate (Na 2 CO 3 ).

Quaternary inorganic compounds

Among them are acid salts and basic salts.

Acid salts

They are formed by the partial replacement of the hydrogen atoms of an oxacid by a metal. For example: sodium bisulfate (NaHSO 4 ).

Basic salts

They originate in reactions in which the hydroxyl groups (OH) are not completely replaced by a non-metal. For example: calcium hydroxychloride [CaCl (OH)].

Examples of inorganic compounds

  • Aluminum oxide (Al 2 O 3 )
  • Chloric oxide (Cl 2 O 5 )
  • Potassium hydroxide (KOH)
  • Ferric hydroxide [Fe (OH) 3 ]
  • Lithium hydride (LiH)
  • Hydrochloric acid (HCl)
  • Sulfuric acid (H 2 SO 4 )
  • Lithium peroxide (Li 2 O 2 )
  • Sodium Chloride (NaCl)
  • Calcium fluoride (CaF 2 )
  • Sodium bicarbonate (NaHCO 3 )
  • Potassium permanganate (KMnO 4 )
  • Water (H 2 O)
  • Carbon dioxide (CO 2 )
  • Ammonia (NH 3 )

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