Chemistry

Chemical classification


Regarding the type of connection

As for the type of binding, the substances are classified as ionic, molecular or metallic. The substances ionic have at least one ionic bond.

Example: NaCl (sodium chloride)
NaNO2 (sodium nitrite)

Ionic substances have high boiling and melting points; many of them, when dissolved in water, have their ions separated by water in a process called ion dissociation; conduct electric current in aqueous solution.

See the table for other examples of ionic substances:

IONIC SUBSTANCE

DESCRIPTION

BARIUM SULPHATE

X-ray used in gastrointestinal tract

CALCIUM OXIDE

Lime

CALCIUM CARBONATE

Marble

Ferric oxide

Rust

MAGNESIUM HYDROXIDE

Antacid

Sodium HYDROXIDE

Caustic soda

The substances molecular they are formed exclusively by covalent bonds. In general, it has a low boiling and melting temperature. Most of them do not conduct electricity in aqueous solution. They form molecules.

Examples: water (H2O)
ammonia (NH3)

See the table for other examples of molecular substances:

MOLECULAR SUBSTANCE

DESCRIPTION

CARBON MONOXIDE

Poison gas from incomplete combustion of gasoline and alcohol

CARBON DIOXIDE

Product of combustion reaction. Absorbed by plants for use in photosynthesis

ETHANOL

Alcohol & Fuel Ingredient

SACAROSIS

Common sugar

The substances metallic they are formed exclusively by metallic connections.

Examples: Iron (Fe), Silver (Ag), Gold (Au), Aluminum (Al).

Regarding the number of chemical elements

As for the number of chemical elements, the substances can be classified as simple or compound.

Simple substance is one formed by a single chemical element. Examples:

Iron (Fe), Aluminum (Al), Hydrogen gas (H2).


Simple Substance - Iron

Composite substance is one formed by more than one type of chemical element. Examples:

Sodium Chloride (NaCl), Carbon Monoxide (CO), Water (H2O).


Composite Substance - NaCl