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400 BCE
Democritus
Born: 460 BC
Died: 370 BC
Occupation: Ancient Greek Philosopher Democritus made a model stating that matter consists of invisible matter called atoms. He also added that they are indestructible and unchangeable, they have no internal structure and that they all come in different size, mass, shape,position and arrangement and that there was a void that exists in the atom -
350 BCE
The Start
Born: 384 BC
Died: 322 BC
Occupation: Ancient Greek Philosopher Aristotle was a Greek philosopher that made a theory that everything was created from four elements; fire, air, water and earth -
Issac Newton
Born: 4 January 1643
Died: 31 March 1727
Occupation: mathematician, astronomer, and physicist Basically he believed that there were little very small bits of mass that were floating everywhere. -
John Dalton
Born: 6 September 1766
Died: 27 July 1844
Occupation: chemist, physicist, meteorologist
John Dalton founded these laws
1.Matter is made up of atoms that are indivisible and indestructible.
2.All atoms of an element are identical.
3.Atoms of different elements have different weights and different chemical properties.
4.Atoms of different elements combine in simple whole numbers to form compounds.
5.Atoms cannot be created or destroyed.When a compound decomposes, the atoms are recovered unchanged. -
Micheal Faraday
Born: 22 September 1791
Died: 25 August 1867
Occupation: Scientist Micheal Faraday who was a scientist who found electromagnetic induction which is the process of starting voltage/ current is produced in a conductor by a changing magnetic flow, He also found diamagnetism which is an attribute of all materials and opposites applied by magnetic fields. He also found electrolysis which is chemical decaying which is produced by passing an electric current through a liquid or solution with ions. -
Julius Plücker
Born: 16 June 1801
Died: 22 May 1868
Occupation: mathematician and physicist His contribution was the invention of Cathode Rays which is a beam of electrons emitted from the negatively charged conductor of a high-vacuum tube. -
Richard Abegg
Born: 9 January 1869
Died: 3 April 1910
occupation: Chemist He proposed that the difference of the maximum amount of positive and negative valence (combining power) of an element which is usually eight -
James Clerk Maxwell
Born: 13 June 1831
Died: 5 November 1879
Occupation: scientist Proposed that there are electric and magnetic fields filled the void. -
Dmitri Mendeleev
Born: 8 February 1834
Died: 2 February 1907
Occupation: chemist and inventor Created the first periodic table and periodic words -
George Johnstone Stoney
Born: 15 February 1826
Died: 5 July 1911
Occupation physicist He invented the word and concept of what know today as the electron and called it the "fundamental unit quantity of electricity" -
Antoine Henri Becquerel
Born: 15 December 1852
Died: 25 August 1908
Occupation: Physicist He discovered Radioactivity. He found this by experimenting with uranium and a photographic plate. He discovered that uranium was giving off invisible radiation and thus radioactivity was found -
Wilhelm Conrad Röntgen
Born: 27 March 1845
Died: 10 February 1923
Occupation: German/Dutch mechanical engineer and physicist He produced and found electromagnetic radiation in a wavelength range which are X-Rays and this also gave him Nobel Peace Prize. -
Max Planck
Born: 23 April 1858
Died: 4 October 1947
occupation: theoretical physicist He proposed the Quantum Theory which is a theory that explains the nature and behaviour of matter and energy on the atomic and subatomic level. -
Frederick Soddy
Born: 2 September 1877
Died: 22 September 1956\
Occupation: Radio chemist He proposed that the same elements exist in different forms, with nuclei having the same number of protons but different numbers of neutrons. His research also led to the discovery of Carbon Dating -
Hantaro Nagaoka
Born: 19 August 1865
Died: 11 December 1950
Occupation: Physicist and pioneer He proposed a planetary model of the atom in which a positively charged centre (the nucleus) is surrounded by a number of revolving electrons (electron cloud) -
Joseph John Thomson
Born: 18 December 1856
Died: 30 August 1940
Occupation: physicist He discovered the electron via a number of expirements and proposed the plum pudding model which is a model of an atom that is a sphere of positive charge , and negatively charged electrons (the plums) which is embedded in it to balance the total amount of positive charge (the pudding). This was proposed before the discovery of nucleus) -
J.J Thompson
he discovered electrons and created the plum pudding model which demonstrates the positive charge to balance the electrons' negative charges, like negatively charged "plums" surrounded by positively charged "pudding" -
Ernest Rutherford
Born: 30 August 1871
Died: 19 October 1937
Occupation: Physicist He conducted an experiment called the Gold-Foil Experiment. A beam of alpha particles is shot at a sheet of gold and some of the beams reflect and he summarising his expirement by theorising that a tiny, hard nucleus was causing the deflections. -
Robert Millikan
Born: 22 March 1868
Died: 19 December 1953
Occupation: Physicist He conducted an experiment which measured the size of the charge on a single electron. There is no unit but instead a ratio which is called charge-to-mass ratio. -
Ernest Rutherford
He made a model called the rutherford model that proposes a middle point called the nucleus and his model also proves the Plum Pudding model is inaccurate -
Hans Geiger
Born: 30 September 1882
Died: 24 September 1945
Occupation: Physicist He co founded the element (Geiger) which led to and expirement called the Geiger–Marsden experiment which also led to the discovery of the atomic nucleus -
Henry Moseley
Born: 23 November 1887
Died: 10 August 1915
Occupation: Physicist He arranged the elements in the periodic table by their number of protons instead of atomic mass. He called this the atomic number. He also studied atomic structure and developed the X-Ray Spectra which is A photon of electromagnetic radiation of very short wavelength which also led to a more accurate version of the Periodic table. -
Francis Aston
Born: 1 September 1877
Died: 20 November 1945
Occupation: chemist and physicist
He invented the mass spectograph which is an analytic technique which changes a chemical species(atom, molecule etc.)into an ion and sorts it based on mass to charge ratio.This happens by having ions deflected off a magnetic field according to their masses. The lighter they are, the more they are deflected. This led to the discovery of isotopic complexity(the elements that are known to be complex in different senses) -
Niels Bohr
Born: 7 October 1885
Died: 18 November 1962
Occupation: Physicist He created the Bohr Model/Diagram which is similar to Rutherford model that he created but he shows an atom as a positively charged nucleus surrounded by electrons that orbit the nucleus in a circular motion. The charge of the electron depends on the size of the orbit and that radiation can occur when one electron jumps from orbit to another. -
Albert Einstein
Born: 14 March 1879
Died: 18 April 1955
Occupation: Theoretical physicist He proposed a theory of relativity which basically means that places that are moving at constant speeds are relative to each other. This also gave him a nobel peace prize. The General theory was published in 1915. -
Wener Heisenberg
Born: 5 December 1901
Died: 1 February 1976
Occupation: Theoretical physicist He discovered and founded quantum mechanics and a way to formulate quantum mechanics in terms of matrices (matrix's) -
Erwin Schrödinger
Born: 12 August 1887
Died: 4 January 1961
Occupation : Physicist He used mathematical equations to describe the chance of finding an electron in an exact position. This made a new model of the atom with an electron cloud and was called the quantum mechanical model of an atom. -
Paul Dirac
Born: 8 August 1902
Died: 20 October 1984
occupation: theoretical physicist He used the Dirac Equation, which depicts the behaviour of a subatomic particle like the electron and predicted the existence of antimatter -
Louis De Broglie
Born: 15 August 1892
Death:19 March 1987
Occupation: French physicist He discovered the wave nature (they can behave like waves) of electrons and suggested that all matter have wave properties(they can behave like waves with a different sizes). He also won a Nobel Prize -
James Chadwick
Born: 20 October 1891
Died: 24 July 1974
Occupation: physicist He discovered the neutron by bombarding beryllium atoms with alpha particles -
John Cockcroft and Ernest Walton
John Cockcroft: Born: 27 May 1897
Died: 18 September 1967
Occupation: Physicist Ernest Walton:
Born: 6 October 1903
Died: 25 June 1995
Occupation: Physicist They both split the atom and discovered the neutron. They did this via nuclear reaction between nitrogen and alpha particles -
Lise meitner, Otto Hahn and Fritz Strassmann,
Lise meitner: Born: 7 November 1878
Died: 27 October 1968
Occupation: physicist Otto Hahn: Born: 8 March 1879
Died: 28 July 1968
Occupation: Chemist Fritz Starssmann:
Born: 22 February 1902
Died: 22 April 1980
Occupation: Chemist They discovered nuclear fission by bombarding uranium with neutrons -
Glenn Seaborg
Born: 19 April 1912
Died: 25 February 1999
Occupation: Chemist He discovered trans-uranium (unstable) elements:plutonium, americium, curium, berkelium, californium, einsteinium, fermium, mendelevium, nobelium and seaborgium which was named after him -
Ernico Ferni
Born: 29 September 1901
Died: 28 November 1954
Occupation: physicist He made the first ever Nuclear Reactor, The first controlled nuclear chain reaction, the B-Decay Theory and his work led to the invention of the first atomic model -
Marie Sklodowska Curie
Born: 7 November 1867
Died: 4 July 1934
Occupation: Physicist and Chemist
She found substances that had were very similar to those like Uranium and were radioactive and similar to those that they use during x-rays, she called them polonium and radium -
Bibliography
Wikipedia sites, Britannica, atomictimeline.net/index.php
