Mr. John Dalton intro.• John Dalton (6 September 1766 – 27 July 1844) was an English chemist, meteorologist and physicist. He is best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness (sometimes referred to as Daltonism, in his honour).
Dalton’s atomic theory….• Elements are made of extremely small particles called atoms.• Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties.• Atoms cannot be subdivided, created, or destroyed.• Atoms of different elements combine in simple whole- number ratios to form chemical compounds.• In chemical reactions, atoms are combined, separated, or rearranged.
Some of his achievements• He was president of the Lit & Phil from 1817 until his death, contributing 116 memoirs.• In 1800, Dalton became a secretary of the Manchester Literary and Philosophical Society, and in the following year he orally presented an important series of papers, entitled "Experimental Essays" on the constitution of mixed gases
Mr. Niels Bohr intro.• Niels Henrik David Bohr (7 October 1885 – 18 November 1962)was a Danish physicist who made foundational contributions to understanding atomic structure and quantum mechanics, for which he received the Nobel Prize in Physics in 1922.
Contribution to physics and chemistry• The Bohr model of the atom, the theory that electrons travel in discrete orbits around the atoms nucleus.• The shell model of the atom, where the chemical properties of an element are determined by the electrons in the outermost orbit.• The correspondence principle, the basic tool of Old quantum theory.• The liquid drop model of the atomic nucleus.• Much work on the Copenhagen interpretation of quantum mechanics.• Identified the isotope of uranium that was responsible for slow-neutron fission – 235U.
Niels’ Achievements• In 1922, Bohr was awarded the Nobel Prize in physics "for his services in the investigation of the structure of atoms and of the radiation emanating from them.• Among the international community of nuclear physicists, Bohr came to play the role of convener of discussion groups and lectures, as well as being a mentor and an advisor.
We thank niel bohr for for histremendous contribution towards physics and chemistry