Chemical Substances

Any material having definite chemical composition is known as chemical substance. The simplest example can be given of water which is a chemical substance with the chemical formula H2O; meaning that one molecule of water is composed of two atoms of hydrogen and one atom of oxygen. Water collected from any place in the world, or made in the laboratory will have the same chemical composition. Water, sugar and salt are general examples of chemical substances found in common household.

One of the prime properties of chemical substance is that they can't be separated into another substances through mechanical process. Chemical substances are generally found in three forms namely solid, liquid and gas. However chemical substances may change their forms due to changes in temperature or pressure. Each chemical substance carries a unique systematic name. There is IUPAC rules available for naming one alternative system of naming is CAS.

Chemical substances which can't be transformed or broken down by ordinary chemical process are known as chemical element or simply element. So far about 120 elements are known. Most of these chemical substances are classified as metal like iron, copper, gold etc.

When two or more elements are combined into one substance form they are known as chemical compound. In a chemical compound atoms of all it's elements are bonded together in molecules. There are approximately 30 million known chemical compounds formed by combination of 120 chemical elements. These compounds are further divided into organic and inorganic compound.

Every matter consists of various elements and chemical compounds, which is often intimately mixed together. Various matters known as mixtures contain more than one chemical substance in varied chemical composition. Soil and wood are common examples of mixture.