Dalton Atomic Theory

 

DALTON ATOMIC THEORY

John Dalton in 1808, formulated a scientific theory. It was the first attempt to describe matter in terms of atoms. The following are the postulates and limitations of Dalton's Atomic Theory.

Postulates:

• All matter is made up of tiny indivisible particles called atoms.
• All atoms of an element are identical in mass and properties.
• An atom of different elements has different properties.
  
• Compounds are formed by different combinations of different atoms.
• Atoms can neither be created nor destroyed. An atom cannot be divided into smaller particles
• A chemical reactant is the rearrangement of atoms.

Limitations:

• According to Dalton's atomic theory atom is indivisible but the discovery of sub-atomic particles disproves its postulate.
• According to Dalton, all atoms of an element have identical masses but actually different atoms of an element (Isotopes) have different masses.
• Allotropes were also not explained by this theory.
• Atoms do not need to combine in simple whole-number ratios to form compounds.

Significance:

Although most of the postulates of Dalton's atomic theory were proved wrong with the advancement in science and technologies still scientist did not discard the theory and continue to design experiments and it paved the way for other scientists to explore new and advance research by testing his theory.