Elements, Compounds and Mixtures

Matter may be classified into elements, compounds, and mixtures.

Element:

An element is a substance which cannot, by any chemical process, be split up into two, or more, simpler substances. There are over 100 known elements scattered in different percentages all over the world. They occur naturally alone or in combination with other materials. Elements are arranged according to their atomic number in a table called a periodic table and may be classified into two groups, metals and non-metals. This classification also is based on the differences in their physical properties.

Examples include – oxygen, hydrogen, chlorine, sodium, magnesium, etc.

Compound:

A compound is a substance which contains two or more elements, chemically combined together. Examples include water (H₂O), carbon (IV) oxide (CO₂), sodium chloride (NaCl), etc.

Mixture:

A mixture contains two or more constituents which can easily be separated by physical methods. The components of mixtures may be elements or compounds or both.

Types of Mixtures:

1. Homogenous Mixture.

2. Heterogeneous Mixture.

Homogenous Mixture: Sometimes called solutions, these are mixtures of relatively uniform composition, where the components are in the same phase, i.e. the constituent cannot be physically distinguished from one another. Examples are sugar solution, air, seawater, brass, salt solution, etc.

Heterogeneous Mixtures are mixtures in which their components are in different phases i.e the constituents can be distinguished from one another when mixed together e.g. kerosene and water, mud water, etc.

Other examples of mixtures are blood, crude oil, soil, urine, palm wine, milk, and coca-cola.

Differences between Mixtures and Compounds:

	Mixtures:	Compounds:
1.	They may be homogenous or heterogeneous.	They are always homogenous.
2.	Constituent elements are not chemically bonded together and therefore can be separated by physical means.	Constituent elements are chemically bonded and cannot be separated by physical methods.
3.	Cannot be represented by chemical formula because the constituents are not in a fixed ratio.	Can be represented by chemical formula because the constituents are present in a fixed ratio.
4.	The properties of mixtures are a sum of their individual elements.	The properties of a compound differ from those of its component elements.