By st12231
• 100

# Ancient Elements

Previous to 1 A.D Gold, Copper, Silver, Iron, Lead, TIn, Mercury, Sulfur and Carbon.
• Period: 100 to

• 460

# Democritus

Born itn the year 460bc his is considered to be one of the farthers of modern science along with aristotle and plato. Although his contributions to science are hard to seperate from his mentor Leucippus they first theorized that all matter is made up of atoms.
• Jan 1, 1250

# Medival Elements

Between 1 A.D and 1700 hundred Arsenic was
Discovered (1250) Phosphorus (1669) Zinc (1300) and Antimony (1700).
• # Sir Isaac Newton

Born on the 25 of december 1642 Sir Issac Newton is considered to be one of the most influential scientists of all time. His work in physics and mathematics was cruical to prove all later discoveris.
• # Elements 1735- 1765

Cobalt (1735), Platinum (1735), Nickel (1751) and
Bismuth (1753)
• # Elements 1765- 1785

Hydrogen (1766), Nitrogen (1772), Oxygen (1774),
Chlorine (1774), Manganese (1774), Molybdenum (1778)
Tungsten (1783) and Tellurium (1782)
• # Elements 1785-1795

Uranium (1841), Strontium (1808), Titanium (1791)
and Yttrium (1794)
• # Elements 1795-1805

Vanadium (1801), Chromium (1797), Beryllium (1798)
Niobium (1801), Tantalum (1802), Cerium (1803)
Palladium (1803), Rhodium (1803), Osmium (1803)
and Iridium (1803)
• # John Dalton

John Dalton was born on the 6 september 1766 and his major contribution to science was that he theorized that elements are made up of only one atom and that different atoms weigh different amounts and that elements cannot be made into simpiler
substances.
• # Elements 1805-1815

Sodium (1807), Potassium (1807), Barium (1808)
Calcium (1808), Magnesium (1775), Boron (1808)
and Iodine (1811)
• # Elements 1815-1835

Lithium (1817), Cadmium (1817), Selenium (1817)
Silicon (1824) ,Zirconium (1789), Aluminum (1827)
Bromine (1826) andThorium (1828)
• # Elements 1835-1875

Lanthanum (1839), Terbium (1843), Erbium (1843)
Ruthenium (1844), Cesium (1860) ,Rubidium (1861) Thallium (1861), Indium (1863) and Fluorine (1866)
• # Periodic Table

On the 6 of March 1869 Dmitri Mendeleev presented his Periodic table which was classified according to the atomic weight and valence of the different elemtents. This was the first widely regarded version of the periodic table. With this periodic table he was able to predict a large number of elements to fit into the gaps of his table. These elements were later discovered proving him correct.
• # Elements 1875- 1885

Gallium (1875), Ytterbium (1878), Samarium (1879)
Scandium (1878), Holmium (1878) andThulium (1879)
• # Elements 1885-1895

Praseodymium (1885), Neodymium (1885), Gadolinium (1880), Dysprosium (1886), Germainium(1886)
and Argon (1894)
• # Elements 1895-1905

Helium (1868), Europium (1890), Krypton (1898)
Neon (1898), Xenon (1898), Polonium (1898)
• # Joseph John Thompson

Born on the 18 December 1856 he discovered the electron and because of this discovery won the 1906 Nobel prize.
• # Elements 1905-1945

Lutetium (1907), Hafnium (1923), Protactinium (1913)
Rhenium (1925), Technetium (1937), Francium (1939)
Astatine (1940), Neptunium (1940), Plutonium (1940) and Curium (1944)
• # Sir Ernest Rutherford

Born on the 30 of August 1871 and he discovered radioactive half life alpha and beta radiation and was awarded a nobel prize in 1908 for his work into the disintergration of atoms and the chemistry of radioactive substances.
• # Neils Bohr

Born on the 1 of October 1885. His biggest contribution to chemistry was the Bohr model of the atom in which the electrons surround the nucleus he also helped develop quantum mechanics.
• # Sir Ernest Rutherford

In 1911 although he could not prove it he theorized that atoms have their charge centered in a very small nucleus. In 1917 he first split the atom in the famous 'gold foil experiement' were at the same time he discovered the existance of the proton.