Dalton's Atomic Theory: The Indestructible Atoms

Dalton’s Atomic Theory

Ever since our existence on this planet, human brain has been curious to understand nature. This curiosity has been the mother of all inventions. Matter has been one of the most important subjects of research for the science enthusiasts. Scientists and philosophers have always tried to simplify things and so was the case with matter. They wanted to know about the fundamental particles that makes matter, their properties, structure etc. This led to the formulation of a number of atomic theories. Democritus was the first man to propose that matter is made up of particles called a atomos meaning indivisible. This was then referred to as Democritus’ Atomic Theory. Due to lack of technological setup back then, information based on this theory was very limited.
Dalton's Atomic Theory
Almost after two millennia, the works on the simplifying matter was materialized by Dalton. In 1808 John Dalton postulated the famous Dalton’s Atomic Theory. He published this theory in a paper titled “A New Chemical Philosophy”; indeed the philosophy was new for that era. The postulates of Dalton’s Atomic Theory were as follows:

  1. Matter is made up of indivisible particles known as atoms.
  2. The properties of all the atoms of a given element are same including mass. This can also be stated as, all the atoms of an element have identical mass; atoms of different elements have different masses.
  3. Atoms of different elements combine in fixed ratios to form compounds.
  4. Atoms are neither created nor destroyed. This implies that during chemical reactions, no atoms are created nor destroyed. The formation of new products (compounds) results from the rearrangement of existing atoms (reactants).

Dalton’s Atomic Theory also suggested that the smallest part of an atom that can take part in a chemical reaction is an atom. Some postulates of this theory remain valid even in modern chemical thoughts. The atomic structure model proposed by Dalton has proved to be a stepping stone in chemistry and forms the base for modern atomic theories and quantum mechanics. Learn more about Dalton’s Atomic Theory with the expert faculties at Byju’s.

Practise This Question

In a hydrogen atom, the electron jumps from one stationary orbit for which n=1 to an orbit for which n=3. If the angular momenta of these levels are Li and Lf respectively, what is the ratio LfLi ?