atomic theories and models

Quantum Mechanical Model of the Atom - Two new theories came to substantially modify Bohr's Atomic model. They a..

In 1913, Neils Bohr proposed a model of an atom based on the Planck's quantum theory of radiation. The basic postulates of Bohr's theory are: * An atom consists of a small, heavily positively charged nucleus around which electrons revolve..

Rutherford proposed that electrons revolve at high speed in circular orbits around the positively charged nucleus. But according to the electromagnetic theory, if a charged particle were accelerated around another charged particle then there would be a continuous radiation of energy. Th..

Rutherford's model had a major drawback. It could not explain why ultimately electrons did not fall into the nucleus by taking a spiral path. This was in concurrence with the electromagnetic theory that states 'if a charged particle undergoes accelerated motion then it must radi..

In 1913, Neils Bohr proposed a model of an atom based on the Planck's quantum theory of radiation. The basic postulates of Bohr's theory are: An atom consists of a small, heavily positively charged nucleus around which electrons revolve in defini..

>As the radiating energy of a revolving electron (according to classical electromagnetic theory) continuously decreases the electron should follow a spiral path and fall into the nucleus. So this atomic model could not account for the stability of the atom. T..

where 'Z' is the nuclear charge, which is equal to atomic number. Although Bohr's model successfully explained the stability and the line spectrum of hydrogen, it had its limitations. They wer..

John Dalton, a British school teacher, published his theory about atoms in the year 1808. His findings were based on experiments and also from laws of chemical combinatio..

John Dalton provided a simple theory of matter to provide theoretical justification to the laws of chemical combinations in 1805. The basic postulates of the theory are: All substances are made up of tiny, indivisible particles called atoms. Atoms of the same..

In view of new discoveries about atoms, Dalton's atomic theory was modified as given below: * Atom is no longer indivisible as it has a complex structure of sub atomic particles (electrons, protons and neutrons). * Atoms of..