Some Basic Concepts of Chemistry

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The combination of elements to form compounds is governed by the  five basic laws:

1. Law of Conservation of Mass
2. Law of Definite Proportions
3. Law of Multiple Proportions
4. Gay Lussac’s Law of Gaseous Volumes
5. Avogadro Law

1. Avogadro proposed that equal volumes of gases at the same temperature and pressure should contain an equal number of molecules.
2. Avogadro made a distinction between atoms and molecules which is quite understandable in the present times.

Gay Lussac’s Law of Gaseous Volumes (Given by Gay Lussac in 1808.)According to this law when gases combine or are produced in a chemical reaction they do so in a simple ratio by volume provided all gases are at same temperature and pressure.

For example H₂(g) (1 vol)+ Cl₂(g)(1 vol) → 2HCl(g) (2 vol)

Law of Conservation of Mass (Given by Antoine Lavoisier in 1789).It states that matter (mass) can neither be created nor destroyed.

This law was proposed by Louis Proust in 1799, which states that: 'A chemical compound always consists of the same elements combined together in the same ratio, irrespective of the method of preparation or the source from where it is taken'.

Law of Multiple Proportions Proposed by Dalton in 1803, this law states that: 'When two elements combine to form two or more compounds, then the different masses of one element, which combine with a fixed mass of the other, bear a simple ratio to one another'.