History of the Atomic Structure

Timeline created by gracelyn_gosnell in Science and Technology

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Event Date:	Event Title:	Event Description:
01/01/1704	Solid Masses in Motion	Isaac Newton proposed a mechanical universe with small solid masses in motion. More Info!
01/01/1785	Indestructible and Unchangeable	Atoms are indestructible and unchangeable. Atoms of an element cannot be created, destroyed, divided into smaller pieces, or transformed into atoms of another element. Dalton based this hypothesis on the law of conservation of mass as stated by Antoine Lavoisier and others around 1785. More Info!
01/01/1803	Atomic Theory	John Dalton proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass. More Info!
01/01/1869	7 Groups of Elements	Dmitri Mendeleev arranged elements into 7 groups with similar properties. He discovered that the properties of elements "were periodic functions of the their atomic weights". This became known as the Periodic Law. More Info!
01/01/1879	Cathode	Sir William Crookes discovered cathode rays had the following properties: travel in straight lines from the cathode; cause glass to fluoresce; impart a negative charge to objects they strike; are deflected by electric fields and magnets to suggest a negative charge; cause pinwheels in their path to spin indicating they have mass. More Info!
01/01/1889	electron	British physicist J.J. Thomson discovered the electron More Info
01/01/1894	Electricity	G.J. Stoney proposed that electricity was made of discrete negative particles he called electrons More Info!
01/01/1898	Alpha and Beta	Rutherford studied radiations emitted from uranium and thorium and named them alpha and beta. More Info
01/01/1919	Isotope Discovery	Aston discovered the existence of isotopes through the use of a mass spectrograph. More Info!
01/01/1922	Atomic Structure - Elements	Niels Bohr developed an explanation of atomic structure that underlies regularities of the periodic table of elements. His atomic model had atoms built up of sucessive orbital shells of electrons. More Info!1922
01/01/1923	Electron waves are similar to light waves	de Broglie Discovered that electrons had a dual nature-similar to both particles and waves. Particle/wave duality. Supported Einstein. More Info!
01/01/1932	Neutron Discovery	James Chadwick using alpha particles discovered a neutral atomic particle with a mass close to a proton. Thus was discovered the neutron. More Info!
12/01/1941	New Periodic Table	Glenn Seaborg synthesized 6 transuranium elements and suggested a change in the layout of the periodic table. More Info!
01/01/1942	Energy from Nucleus	Enrico Fermi conducted the first controlled chain reaction releasing energy from the atoms nucleus. More Info!