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Henry Cavendish
The Cavendish experiment, performed in 1797–98 by British scientist Henry Cavendish was the first experiment to measure the force of gravity between masses in the laboratory, and the first to yield accurate values for the gravitational constant. Because of the unit conventions then in use, the gravitational constant does not appear explicitly in Cavendish's work. Instead, the result was originally expressed as the specific gravity of the Earth, -
John Dalton
John Dalton discpvered elements that appeared in the table namely hydrogen, oxygen, nitrogen, carbon, sulfur, and phosphorus, with the atom of hydrogen conventionally assumed to weigh . Dalton provided no indication in this first paper how he had arrived at these numbers.However, in his laboratory notebook under the date 6 September 1803, there appears a list in which he sets out the relative weights of the atoms of a no a number of elements, derived from analysis of water, ammonia, carbon diox -
Joseph Proust
In chemistry, the law of definite proportions, sometimes called Proust's Law, states that a chemical compound always contains exactly the same proportion of elements by mass. An equivalent statement is the law of constant composition, which states that all samples of a given chemical compound have the same elemental composition. For example, oxygen makes up about 8/9 of the mass of any sample of pure water, while hydrogen makes up the remaining 1/9 of the mass. Along with the law of multiple pro -
Joseph Louis Gay-Lussac
The expression Gay-Lussac's law is used for each of the two relationships named after the French chemist Joseph Louis Gay-Lussac and which concern the properties of gases, though it is more usually applied to his law of combining volumes, the first listed here. One law relates to volumes before and after a chemical reaction while the other concerns the pressure and temperature relationship for a sample of gas. -
Medeleev
The history of the periodic table reflects over a century of growth in the understanding of chemical properties, and culminates with the publication of the first actual periodic table by Dmitri Mendeleev in 1869.While Mendeleev built upon earlier discoveries by such scientists as Antoine-Laurent de Lavoisier and Stanislao Cannizzaro, the Russian scientist is generally given sole credit for development of the actual periodic table itself. -
John Strutt
The existence of Rayleigh waves was predicted in 1885 by Lord Rayleigh, after whom they were namedRayleigh waves have a speed slightly less than shear waves by a factor dependent on the elastic constants of the material. The typical speed is of the order of 2–5 km/s. -
John Thomson
. He is credited for the discovery of the electron and of isotopes, and the invention of the mass spectrometer.Thomson, in 1897, was the first to suggest that the fundamental unit was over 1000 times smaller than an atom, suggesting the sub-atomic particles now known as electrons. Thomson discovered this through his explorations on the properties of cathode rays. -
Max Planck
Max Planck found that the energy of the wavelength could be calculated.The Planck constant (denoted h), also called Planck's constant, is a physical constant reflecting the sizes of energy quanta in quantum mechanics. It is named after Max Planck, one of the founders of quantum theory, who discovered it in 1900. Classical statistical mechanics requires the existence of h -
Hantaro Nagaoka
Physicists in 1900 had just begun to consider the structure of the atom. The recent discovery by J. J. Thomson of the negatively charged electron implied that a neutral atom must also contain an opposite positive charge. In 1903 Thomson had suggested that the atom was a sphere of uniform positive electrification, with electrons scattered through it like plums in a pudding, the plum pudding model.Nagaoka rejected Thomson's model on the ground that opposite charges are impenetrable. He proposed -
Democritus
In chemistry and physics, atomic theory is a theory of the nature of matter, which states that matter is composed of discrete units called atoms, as opposed to the obsolete notion that matter could be divided into any arbitrarily small quantity. It began as a philosophical concept in ancient Greece (Democritus) and India and entered the scientific mainstream in the early 19th century when discoveries in the field of chemistry showed that matter did indeed behave as if it were made up of particle -
Ernest Rutherford
In 1911, Rutherford came forth with his own physical model for subatomic structure, as an interpretation for the unexpected experimental results. In it, the atom is made up of a central charge surrounded by a cloud of orbiting electrons. In this May 1911 paper, Rutherford only commits himself to a small central region of very high positive or negative charge in the atom. -
Bohr Model
In atomic physics, the Bohr model, introduced by Niels Bohr in 1913, depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus.This was an improvement on the earlier cubic model . -
James Chadwick
Atomic theory was discovered many years back by a famous physicist Mr. James Chadwick. He discovered that except the both negatively charged atoms called electron and positively charged proton there is one other tiny particle in an atom that is called a neutron, which is found to be neutral from both positive and negative charges. According to the James Chadwick Atomic Theory, a neutron is a very tiny but important particle which present in the central part of an atom called nucleus. -
Norman Ramsey
In1960, Ramsey invented an atomic clock based on the hydrogen maser, a design used today in Global Positioning System satellites.In 1949, while working at Harvard, Ramsey applied a key insight to improve Columbia University physicist Isidor Rabi's method of studying atoms and molecules. In 1937, Rabi used alternating magnetic fields to characterize atomic matter. Ramsey exposed the atoms to the magnetic field only as they entered or exited his device.
