Leucippus or Leukippos wasHe was a (born c. 460 — one of the earliest Greeks todied c. 370 BC) Greek develop the theory ofphilosopher. atomism• He was an Ancient Greek Philosopher born • He was born in Miletus and spent in Abdera, Thrace in Greece. the rest of his life in Abdera.Leucippus was his mentor. Democrituswas his student.• Yuh. Democritus. • Yuh. Leucippus.
held that everything is composed of "atoms― ―Atoms‖ are physically, but not geometrically, indivisible. that between atoms lies empty space; that atoms are indestructible; have always been, and always will be, in motion that there are an infinite number of atoms There are different kinds of atoms, which differ in shape, and size. Democritus said "The more any indivisible exceeds, the heavier it is." But his exact position on weight of atoms is disputed.
Atomic Theory ROBERT BOYLERobert Boyle FRS (25 Boyle is best remembered for Boyles law, aJanuary 1627 – 31 physical law that explains how the pressure and volume of a gas are related.December 1691) was a17th century natural He advanced the view that the basic elements of matter are "corpuscles," or particles, ofphilosopher, chemist, ph various sorts and sizes. Boyle believed thatysicist, and iventor, also these corpuscles were capable of arrangingnoted for his writings themselves into groups, and that each groupin theology. constituted a chemical substance.He is best known He successfully distinguished betweenfor Boyles law. mixtures (substances mixed together) and compounds (chemically bonded substances) and showed that a compound can have very different qualities from those of its constituents.
AntoineLavoisier considerInature a vast Born: 26 August 1743chemical Birthplace: Paris, Francelaboratory in Died: 8 May 1794 (beheading)which all kinds Best Known As: French chemistof composition who proved the law of conservation ofand massdecompositions Because of his achievements he isare formed. sometimes called the father ofAntoine modern chemistry.Lavoisier
Antoine Lavoisier’s contribution to atomic theory Antoine Lavoisier was the first person to make good use of the balance. After a visit with Priestly in 1774, he began careful study of the burning process. He proposed the Combustion Theory which was based on sound mass measurements. He named oxygen. He also proposed the Law of Conversation of Mass which represents the beginning of modern chemistry.
Joseph Proust Joseph Proust proposed the the Law of Constant Composition in 1799. Law of Definite Proportions ( also called Law of Constant Composition) –states that a given compound always has the same elements in the same proportion by mass.
J. Berzelius (Jöns Jacob Berzelius) Jöns Jacob Berzelius (20 August 1779 – 7 August 1848) was a Swedish chemist. He worked out the modern technique of chemical formula notation, and is together with John Dalton, Antoine Lavoisier, and Robert Boyle considered a father of modern chemistry.
The most notable of Berzeliuss contributions to chemistry was his development of a rational system of atomic symbols. Around 1810 Berzelius was working to confirm John Daltons atomic theory as well as Prousts law showing that separate elements always combined in whole-number proportions. Berzelius came to the conclusion that the existing system of denoting elements and compounds was a hindrance. In establishing his own atomic symbols, He stated that "it is easier to write an abbreviated word than to draw a figure which has little analogy with words" Berzelius opted to use the first letter of the Latin name for each element as its symbol.
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).
All matter is made of atoms. Atoms are indivisible and indestructible. All atoms of a given element are identical in mass and properties Compounds are formed by a combination of two or more different kinds of atoms. A chemical reaction is arearrangement of atoms.
J.J Thomson• Sir Joseph John "J. J." Thomson, (18 December 1856 – 30 August 1940) was aBritish physicist and Nobel laureate.• He is credited for the discovery of the electron and of isotopes, and the invention of the ,mass spectrometer.
JJ Thomsons major contributions tothe atomic theory..• His atomic theory identified that electrons inside an atom could show, meaning that atoms were not invisible. Thomson suggested that the model of an atom as a sphere of positively charged matter with negatively charged electrons surrounding them.• He stated that electrons were positioned by electrostatic forces.• After the discovery of the electron and proton as subatomic particles J.J. Thomson had started to discover atomic theory that gives complete explanation of atomic structure.According to Thomson protons are embed in the atoms like a water melon and electrons are present in atoms to make the atom electrically neutral.
ERNEST RUTHERFORD Ernest Rutherford, 1st Baron Rutherford of Nelson (30 August 1871 – 19 October 1937) was a New Zealand- born British chemist and physicist who became known as the father of nuclear physics He was awarded in 1908 "for his investigations into the disintegration of the elements, and the chemistry of radioactive substances".
RUTHERFORDS ATOMICTHEORY -ELECTRONEGATIVITY Ernest Rutherford publishes his atomic theory describing the atom as having a central positive nucleus surrounded by negative orbiting electrons. Rutherford came to this conclusion following the results of his famous gold foil experiment. Rutherford found that although the vast majority of particles passed straight through the foil approximately 1 in 8000 were deflected leading him to his theory that most of the atom was made up of empty space.
Niels Bohr Niels Henrik David Bohr (October 1885 – 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.
Bohr’s Atomic Theory Neils Bohr postulated based on quantum theory that electrons travel around an atomic nucleus in a stationary orbit. Relegates the number of valence electrons to the Periods of a periodic table Fully explains ionic and covalent bonding His work also led to the theory of different energy levels in atoms, that is if an electron drops from a higher to a lower orbit, it must release energy.