-
460
Democritus
• Democritus lived from 460BC to 370BC.
• He theorized that everything was made from an atom.
• He claimed that an object can be divided so many times that eventually you will be left with an indestructible particle, which he called an atom. -
Isaac Newton
• Issac Newton was born 25th December 1642 and died 20th March 1727.• He did not specifically contribute anything to the atomic theory, but quantum mechanics helped develop the atomic theory, and it was based souly on Newtons mechanical work. -
John Dalton
• John Dalton was born 6 September 1766 and died 27 July 1844.• He thought that all matter was made of atoms and that atoms could not be made or destroyed and were identical. • He also theorized that chemical reactions occur when atoms are rearranged. -
George Johnstone Stoney
• George Johnstone Stoney was born February 15th, 1826 and died July 5th 1911. • He introduced the term ‘electron’ and stated this to be the ‘fundamental unit quantity of electricity’. -
Dmitri Mendeleev
• Dmitri Mendeleev was born February 8th 1834 and died February 2nd 1907.• It was Dmitri Mendeleev who invented the periodic table.• He had cards with various elements on them, and arranged them in order of atomic mass, noticing that there were similarities in their chemical properties. This inspired the name “Periodic Table”.• His first table was published in 1869. -
J.J Thomson
• Joseph was born on 18th December 1856 and died 30th August 1940.• Joseph John Thomson discovered electrons and developed the ‘Plum-Pudding’ model of the atom, as it was his interpretation of what an atom looked like. -
Ernest Rutherford
• Ernest Rutherford was born 30th August 1871, and died 19th October 1937. • He conducted an experiment involving gold foil and observing the behaviour of particles being shot through the piece of gold foil. With these results, he stated that all of the mass of an atom was in a small positively charged ball in the middle of the atom, the nucleus. -
Otto Hahn
• Otto Hahn was born March 8th 1879 and died July 28th 1968.• Otto Hahn discovered Nuclear Fisson, where the nucleus of an atom can be split into two separate parts, while he was experimenting with uranium. -
Neils Bohr
• Neils Bohr was born 7th Octover 1885 and died November 18th 1962. • Neils Bohr stated that electrons travelled around the nucleus in a stationary orbit. • His work also lead to the theory that if electrons drop from a higher to lower orbit that some form of energy must be released.• He also introduced the Bohr atomic model and received a nobel prize in Physics in 1922. -
Erwin Schrodinger
• Born in 1887 in Austria and died in 1961.• Looked at Bohr’s atomic theory and improved it.• He used mathematical equations to describe the chances of finding an electron in a particular area. This is known as the quantum mechanical model.• It doesn’t describe the exact path of an electron like Bohr’s, but predicts the odds of the location of an electron. -
Henry Moseley
• Henry Moseley was born November 23rd, 1887 and died August 10th, 1915. • He developed X-rays to study the atomic structure. Using this, Moseley was able to determine the number of positive charges in the nucleus of an atom, and this was the first concept of the atomic number. -
James Chadwick
• James Chadwick was born 20th October 1891 and died July 24th 1974. • James Chadwick proved that neutrons exhisted and were a similar mass to protons when he discovered a particle inside the nucleus that had a similar mass to the proton. -
John Douglas Cockcroft and Ernest Thomas Sinton Walton
• John Douglas Cockroft was born May 27th 1897 and died September 18th, 1967 and Ernest Thomas Sinton Walton was born 6th October 1903, and died • John and Ernest built the first linear accelerator which is a powerful radio frequency system. They used this to bombard lithium with aprotons. • They also split the atom for the first time. -
Paul Dirac
• Born in august 1902,• Died 1984,• Dirac established the most general theory of quantum mechanics and discovered the equation for the electron. He was the first to develop quantum field theory, which is the base for all theotorical work on sub-atomic atoms.• He received a nobel prize in 1933. -
Aristotle
• Aristotle was born 384 BC and died 322 BC.
• He believed that all matter consisted of the four elements, Earth, Air, Water, and Fire, and that there were four qualities; dryness, hotness, coldnedd and moistness.
• Aristotles theory had 2 forces, conflict and harmony. • Aristotles theory was used for nearly 2000 years until the scientific revolution.
