Chemistry Definitions

Chemistry

Chemistry is the science of materials of the universe.

Physical Chemistry

The branch of Chemistry that deals with laws and theories to understand the structure and changes of matter is called Physical Chemistry.

Organic Chemistry

Organic chemistry deals with carbon compounds.

Inorganic Chemistry

The branch of Chemistry that deals with elements and their compounds except organic compounds is called Inorganic Chemistry.

Biochemistry

Physical and chemical changes that occur in living organisms are studied in biochemistry.

Industrial Chemistry

Industrial chemistry is concerned with the large-scale production of chemical substances.

Element

An element is a substance whose all the atoms have the same atomic number.

Compound

A compound consists of two or more elements held together in fixed proportions by chemical bonds.

Mixture

An impure substance that contains two or more pure substances that retain their individual chemical characteristics is called a mixture.

Atomic Number

The number of protons in the nucleus of an atom is known as its atomic number.

Mass Number

The total number of protons and neutrons in an atom is called its mass number.

Isotope

Atoms of an element that have different numbers of neutrons are called isotopes.

Relative Atomic Mass

The mass of an atom of an element relative to the mass of an atom of C-12 is called relative atomic mass.

Atomic Mass Unit (AMU)

One atomic mass unit is defined as the mass exactly equal to one-twelfth the mass of one C-12 atom.

Empirical Formula

Chemical formula of a compound that gives the simplest whole-number ratio between atoms is called empirical formula.

Molecular Formula

Molecular formula of a compound gives the exact number of atoms present in a molecule.

Molecular Mass

Molecular mass is the sum of atomic masses of all the atoms present in the molecule.

Cations and Anions

Positively charged ions are called cations, and negatively charged ions are called anions.

Molecular Ion

When a molecule loses or gains electrons, the resulting species is called a molecular ion.

Free Radical

Free radical is an atom or group of atoms that contains an unpaired electron.

Avogadro’s Number

The number of representative particles in one mole of the substance is known as Avogadro’s number.

Mole

The amount of matter that contains as many atoms, ions or molecules as the number of atoms in exactly 12g of C-12 is called mole. Mole can also be defined as atomic mass, molecular mass or formula mass expressed in grams.

Gram Atomic Mass

Atomic mass of an element expressed in grams is called gram atomic mass.

Gram Molecular Mass

Molecular mass of an element or a compound expressed in grams is its gram molecular mass.

Gram Formula Mass

Gram formula mass is the formula mass of a substance in grams.