Molecule Element Compound

Matter is chemically classified as Elements, compounds and mixtures.

Dalton had proposed that atoms of the same or different elements combine with one another to form compound atoms. These compound atoms later came to be known as molecules.  Avogadro made a clear distinction between atoms and molecules. According to him, atom is the smallest particle of an element which can take part in a chemical reaction. It may or may not be capable of independent existence.

Molecule Element Compound:molecule

Molecule is the smallest particle of matter(element or compound) which can exist independently. It may be made up of the atoms of the same or different elements For example, N2 contains only Nitrogen and it is one molecule of Nitrogen. CO2 is one molecule of carbon dioxide. It contains one atom of carbon and two atoms of oxygen.

Atoms combine to give molecules, and molecules combine to give elements. Elements combine to give compounds.
Molecule Element Compound : Elements

Elements are substances which cannot be reduced to simpler materials either by physical or chemical changes. Examples are iron, copper, gold, silver etc. At present 105 elements are known. About 90 of the elements can be extracted from natural sources but the rest can be prepared artificially by means of nuclear processes.

Molecule Element Compound : Compounds

Compounds are substances which have been formed by the combination of two or more different elements in a definite ratio.Millions of compounds are known because of the different combinations of the 105 elements.  A few examples are water, ammonia, methane, and benzene. Out of these, water and ammonia are examples of inorganic compounds, and methane and benzene are examples of organic compounds.

Elements and compounds are known as pure substances because their composition and properties are uniform throughout in any given sample. However, most of the naturally occurring substances are neither pure elements nor pure compounds but generally mixtures of both.