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The INTERNET Database of Periodic Tables

There are thousands of periodic tables in web space, but this is the only comprehensive database of periodic tables & periodic system formulations. If you know of an interesting periodic table that is missing, please contact the database curator: Mark R. Leach Ph.D.

Use the drop menus below to search & select from the more than 1100 Period Tables in the database:

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Elements by Date:

9000 BCE   Discovery of Copper
7000 BCE   Discovery of Lead
6000 BCE   Discovery of Gold
5000 BCE   Discovery of Iron
5000 BCE   Discovery of Silver
3750 BCE   Discovery of Carbon
3500 BCE   Discovery of Tin
2000 BCE   Discovery of Sulfur (Sulphur)
2000 BCE   Discovery of Mercury
1000 BCE   Discovery of Zinc
800 BCE   Discovery of Antimony
300 BCE   Discovery of Arsenic
1669   Discovery of Phosphorus
1735   Discovery of Cobalt
1748   Discovery of Platinum
1751   Discovery of Nickel
1753   Discovery of Bismuth
1766   Discovery of Hydrogen
1771   Discovery of Oxygen
1772   Discovery of Nitrogen
1774   Discovery of Chlorine
1774   Discovery of Manganese
1781   Discovery of Molybdenum
1782   Discovery of Tellurium
1783   Discovery of Tungsten
1789   Discovery of Zirconium
1789   Discovery of Uranium
1791   Discovery of Titanium
1794   Discovery of Yttrium
1798   Discovery of Beryllium
1798   Discovery of Chromium
1801   Discovery of Niobium
1802   Discovery of Tantalum
1803   Discovery of Palladium
1803   Discovery of Cerium
1803   Discovery of Osmium
1803   Discovery of Iridium
1804   Discovery of Rhodium
1807   Discovery of Sodium
1807   Discovery of Potassium
1808   Discovery of Boron
1808   Discovery of Magnesium
1808   Discovery of Calcium
1808   Discovery of Strontium
1808   Discovery of Barium
1811   Discovery of Iodine
1817   Discovery of Lithium
1817   Discovery of Selenium
1817   Discovery of Cadmium
1824   Discovery of Silicon
1825   Discovery of Aluminium (Aluminum)
1825   Discovery of Bromine
1829   Discovery of Thorium
1830   Discovery of Vanadium
1838   Discovery of Lanthanum
1842   Discovery of Terbium
1842   Discovery of Erbium
1844   Discovery of Ruthenium
1860   Discovery of Cesium
1861   Discovery of Rubidium
1861   Discovery of Thallium
1863   Discovery of Indium
1875   Discovery of Gallium
1878   Discovery of Ytterbium
1879   Discovery of Scandium
1879   Discovery of Samarium
1879   Discovery of Holmium
1879   Discovery of Thulium
1880   Discovery of Gadolinium
1885   Discovery of Praseodymium
1885   Discovery of Neodymium
1886   Discovery of Fluorine
1886   Discovery of Germanium
1886   Discovery of Dysprosium
1894   Discovery of Argon
1895   Discovery of Helium
1898   Discovery of Neon
1898   Discovery of Krypton
1898   Discovery of Xenon
1898   Discovery of Polonium
1898   Discovery of Radium
1899   Discovery of Radon
1901   Discovery of Europium
1902   Discovery of Actinium
1906   Discovery of Lutetium
1913   Discovery of Protactinium
1919   Discovery of Rhenium
1922   Discovery of Hafnium
1937   Discovery of Technetium
1939   Discovery of Francium
1940   Discovery of Astatine
1940   Discovery of Neptunium
1940   Discovery of Plutonium
1944   Discovery of Americium
1944   Discovery of Curium
1945   Discovery of Promethium
1949   Discovery of Berkelium
1950   Discovery of Californium
1952   Discovery of Einsteinium
1952   Discovery of Fermium
1955   Discovery of Mendelevium
1955   Element Hunters
1961   Discovery of Lawrencium
1966   Discovery of Nobelium
1969   Discovery of Rutherfordium
1970   Discovery of Dubnium
1974   Discovery of Seaborgium
1981   Discovery of Bohrium
1982   Discovery of Meitnerium
1984   Discovery of Hassium
1994   Discovery of Darmstadtium
1994   Discovery of Roentgenium
1996   Discovery of Copernicium
1999   Discovery of Flerovium
2000   Discovery of Livermorium
2002   Discovery of Oganesson
2003   Discovery of Nihonium
2003   Discovery of Moscovium
2010   Discovery of Tennessine


9000 BCE

Discovery of Copper

Cu

Copper, atomic number 29, has a mass of 63.546 au.

Copper had its earliest use in about 9000 BCE, and the oldest sample dates from 6000 BCE. It was discovered by Middle East workers and the earliest sample is from Anatolia.

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7000 BCE

Discovery of Lead

Pb

Lead, atomic number 82, has a mass of 207.2 au.

Lead had its earliest use in about 7000 BCE, and the oldest sample dates from 3800 BCE. It was discovered by Africa and the earliest sample is from Abydos, Egypt.

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6000 BCE

Discovery of Gold

Au

Gold, atomic number 79, has a mass of 196.967 au.

Gold had its earliest use in about 6000 BCE, and the oldest sample dates from 4400 BCE. It was discovered by Bulgaria and the earliest sample is from Varna Necropolis.

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5000 BCE

Discovery of Iron

Fe

Iron, atomic number 26, has a mass of 55.845 au.

Iron had its earliest use in about 5000 BCE, and the oldest sample dates from 4000 BCE from Egypt.

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5000 BCE

Discovery of Silver

Ag

Silver, atomic number 47, has a mass of 107.868 au.

Silver had its earliest use in about 5000 BCE, and the oldest sample dates from 4000 BCE, and is from Asia Minor.

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3750 BCE

Discovery of Carbon

C

Carbon, atomic number 6, has a mass of 12.011 au.

Carbon has many allotropes, including: graphite, diamond, graphene, C60, single wall nanotubes, etc.

Carbon had its earliest use in about 3750 BCE. It was discovered by Egyptians and Sumerians.

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3500 BCE

Discovery of Tin

Sn

Tin, atomic number 50, has a mass of 118.71 au.

Tin + copper gives bronze, and so the Bronze Age.

Tin had its earliest use in about 3500 BCE, and the oldest sample dates from 2000 BCE. It is unknown who discovered the element.

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2000 BCE

Discovery of Sulfur (Sulphur)

S

Sulfur, atomic number 16, has a mass of 32.068 au.

Sulfur is a pale yellow, odourless, brittle solid.

Sulfur had its earliest use in about 2000 BCE. It was discovered by Chinese/Indians.

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2000 BCE

Discovery of Mercury

Hg

Mercury, atomic number 80, has a mass of 200.592 au.

Mercury had its earliest use in about 2000 BCE, and the oldest sample dates from 1500 BCE. It was discovered by Chinese/Indians and the earliest sample is from Egypt.

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1000 BCE

Discovery of Zinc

Zn

Zinc, atomic number 30, has a mass of 65.38 au.

Zinc had its earliest use in about 1000 BCE, and the oldest sample dates from 1000 BCE. It was discovered by Indian metallurgists and the earliest sample is from the Indian subcontinent.

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800 BCE

Discovery of Antimony

Sb

Antimony, atomic number 51, has a mass of 121.76 au.

Antimony had its earliest use in about 800 BCE.

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300 BCE

Discovery of Arsenic

As

Arsenic, atomic number 33, has a mass of 74.922 au.

Arsenic had its earliest use in about 300 BCE.

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1669

Discovery of Phosphorus

P

Phosphorus, atomic number 15, has a mass of 30.974 au.

Phosphorus exists in several allotropic forms including: white, red and black.

Phosphorus was first isolated in 1669 by H. Brand.

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1735

Discovery of Cobalt

Co

Cobalt, atomic number 27, has a mass of 58.933 au.

Cobalt was first isolated in 1735 by G. Brandt.

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1748

Discovery of Platinum

Pt

Platinum, atomic number 78, has a mass of 195.084 au.

Platinum was first isolated in 1748 by A. de Ulloa, although it had been used by pre-Colombian Americans.

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1751

Discovery of Nickel

Ni

Nickel, atomic number 28, has a mass of 58.693 au.

Nickel was first isolated in 1751 by F. Cronstedt.

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1753

Discovery of Bismuth

Bi

Bismuth, atomic number 83, has a mass of 208.98 au.

Bismuth was first isolated in 1753 by C.F. Geoffroy.

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1766

Discovery of Hydrogen

H

Hydrogen, atomic number 1, has a mass of 1.008 au.

Hydrogen is the lightest element and by far the most abundant element in the universe: it makes up about about 90% of the universe by weight. Under standard conditions, hydrogen exists as a diatomic molecular gas, H2.

Hydrogen was first isolated and identified as an element in 1766 by H. Cavendish, although it was first made in 1500 by Paracelsus.

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1771

Discovery of Oxygen

O

Oxygen, atomic number 8, has a mass of 15.999 au.

Oxygen exists as a diatomic molecular gas, O2; in this form it makes up about 20% of the atmosphere.

Oxygen was first isolated in 1771 by W. Scheele.

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1772

Discovery of Nitrogen

N

Nitrogen, atomic number 7, has a mass of 14.007 au.

Nitrogen exists as a diatomic molecular gas, N2, and in this form it makes up about 78% of the atmosphere by volume. The element seemed so inert that Lavoisier named it azote, meaning "without life".

Nitrogen was first isolated in 1772 by D. Rutherford.

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1774

Discovery of Chlorine

Cl

Chlorine, atomic number 17, has a mass of 35.452 au.

Chlorine exists as a green diatomic molecular gas, Cl2.

Chlorine was first isolated in 1774 by W. Scheele.

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1774

Discovery of Manganese

Mn

Manganese, atomic number 25, has a mass of 54.938 au.

Manganese was first observed or predicted in 1774 by W. Scheele and first isolated in 1774 by G. Gahn.

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1781

Discovery of Molybdenum

Mo

Molybdenum, atomic number 42, has a mass of 95.95 au.

Molybdenum was first observed or predicted in 1778 by W. Scheele and first isolated in 1781 by J. Hjelm.

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1782

Discovery of Tellurium

Te

Tellurium, atomic number 52, has a mass of 127.6 au.

Tellurium caused great difficulty to the chemists who first tried to develop a periodic table, because it has an atomic weight greater than iodine (126.9). Mendeleev prioritised chemical properties over the anomalous atomic weight data, and correctly classified Te along with O, S, & Se. It was only when nuclear structure and the importance of atomic number was recognised, around 1918, that the issue was explained.

Tellurium was first isolated in 1782 by F.-J.M. von Reichenstein.

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1783

Discovery of Tungsten

W

Tungsten, atomic number 74, has a mass of 183.84 au.

Tungsten was first observed or predicted in 1781 by W. Scheele and first isolated in 1783 by J. and F. Elhuyar.

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1789

Discovery of Zirconium

Zr

Zirconium, atomic number 40, has a mass of 91.224 au.

Zirconium was first observed or predicted in 1789 by H. Klaproth and first isolated in 1824 by J. Berzelius.

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1789

Discovery of Uranium

U

Uranium, atomic number 92, has a mass of 238.029 au.

Radioactive element with a very long half-life.

Uranium was first observed or predicted in 1789 by H. Klaproth and first isolated in 1841 by E.-M. Péligot.

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1791

Discovery of Titanium

Ti

Titanium, atomic number 22, has a mass of 47.867 au.

Titanium was first observed or predicted in 1791 by W. Gregor and first isolated in 1825 by J. Berzelius.

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1794

Discovery of Yttrium

Y

Yttrium, atomic number 39, has a mass of 88.906 au.

Yttrium was first observed or predicted in 1794 by J. Gadolin and first isolated in 1842 by G. Mosander.

Chronology of chemically the splitting of yttria (mixed oxides) into the pure rare-earth metals:

From: CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis
by Pieter Thyssen and Koen Binnemans (ISBN: 978-0-444-53590-0)

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1798

Discovery of Beryllium

Be

Beryllium, atomic number 4, has a mass of 9.012 au.

Beryllium is a metal with a high melting point. At ordinary temperatures it resists oxidation in air. Beryllium compounds are very toxic.

Beryllium was first observed or predicted in 1798 by N. Vauquelin and first isolated in 1828 by F. Wöhler and A. Bussy.

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1798

Discovery of Chromium

Cr

Chromium, atomic number 24, has a mass of 51.996 au.

Chromium was first observed or predicted in 1797 by N. Vauquelin and first isolated in 1798 by N. Vauquelin.

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1801

Discovery of Niobium

Nb

Niobium, atomic number 41, has a mass of 92.906 au.

Niobium was first observed or predicted in 1801 by C. Hatchett and first isolated in 1864 by W. Blomstrand.

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1802

Discovery of Tantalum

Ta

Tantalum, atomic number 73, has a mass of 180.948 au.

Tantalum was first isolated in 1802 by G. Ekeberg.

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1803

Discovery of Palladium

Pd

Palladium, atomic number 46, has a mass of 106.42 au.

Palladium was first isolated in 1803 by H. Wollaston.

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1803

Discovery of Cerium

Ce

Cerium, atomic number 58, has a mass of 140.116 au.

Cerium was first observed or predicted in 1803 by H. Klaproth, J. Berzelius, and W. Hisinger and first isolated in 1838 by G. Mosander.

Chronology of chemically the splitting of ceria (mixed oxides) into the pure rare-earth metals:

From: CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis
by Pieter Thyssen and Koen Binnemans (ISBN: 978-0-444-53590-0)

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1803

Discovery of Osmium

Os

Osmium, atomic number 76, has a mass of 190.23 au.

Osmium was first isolated in 1803 by S. Tennant.

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1803

Discovery of Iridium

Ir

Iridium, atomic number 77, has a mass of 192.217 au.

Iridium was first isolated in 1803 by S. Tennant.

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1804

Discovery of Rhodium

Rh

Rhodium, atomic number 45, has a mass of 102.906 au.

Rhodium was first isolated in 1804 by H. Wollaston.

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1807

Discovery of Sodium

Na

Sodium, atomic number 11, has a mass of 22.99 au.

Sodium is a Group 1 element, and these are often referred to as the "alkali metals".

Sodium was first isolated in 1807 by H. Davy.

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1807

Discovery of Potassium

K

Potassium, atomic number 19, has a mass of 39.098 au.

Potassium is a Group 1 element, and these are often referred to as the "alkali metals".

Potassium was first isolated in 1807 by H. Davy.

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1808

Discovery of Boron

B

Boron, atomic number 5, has a mass of 10.814 au.

Boron has properties that are borderline between metal and non-metal (semimetallic).

Boron was first observed or predicted in 1808 by L. Gay-Lussac and L.J. Thénard and first isolated in 1808 by H. Davy.

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1808

Discovery of Magnesium

Mg

Magnesium, atomic number 12, has a mass of 24.306 au.

Magnesium is a Group 2 element, and these are called: "alkaline earth metals".

Magnesium was first observed or predicted in 1755 by J. Black and first isolated in 1808 by H. Davy.

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1808

Discovery of Calcium

Ca

Calcium, atomic number 20, has a mass of 40.078 au.

Calcium is a Group 2 element, and these are called: "alkaline earth metals".

Calcium was first isolated in 1808 by H. Davy.

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1808

Discovery of Strontium

Sr

Strontium, atomic number 38, has a mass of 87.62 au.

Strontium is a Group 2 element, and these are called: "alkaline earth metals".

Strontium was first observed or predicted in 1787 by W. Cruikshank and first isolated in 1808 by H. Davy.

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1808

Discovery of Barium

Ba

Barium, atomic number 56, has a mass of 137.327 au.

Barium is a Group 2 element, and these are called: "alkaline earth metals".

Barium was first observed or predicted in 1772 by W. Scheele and first isolated in 1808 by H. Davy.

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1811

Discovery of Iodine

I

Iodine, atomic number 53, has a mass of 126.904 au.

Iodine exists as a black diatomic molecular solid, I2.

Iodine was first isolated in 1811 by B. Courtois.

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1817

Discovery of Lithium

Li

Lithium, atomic number 3, has a mass of 6.968 au.

Lithium is a reactive metal, of low density: it is the least dense metal.

Lithium was first observed or predicted in 1817 by A. Arfwedson and first isolated in 1821 by W. T. Brande.

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1817

Discovery of Selenium

Se

Selenium, atomic number 34, has a mass of 78.971 au.

Selenium was first isolated in 1817 by J. Berzelius and G. Gahn.

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1817

Discovery of Cadmium

Cd

Cadmium, atomic number 48, has a mass of 112.414 au.

Cadmium was first isolated in 1817 by S. L Hermann, F. Stromeyer and J.C.H. Roloff.

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1824

Discovery of Silicon

Si

Silicon, atomic number 14, has a mass of 28.085 au.

Silicon makes up 25.7% of the earth's crust, and after oxygen is the second most abundant element.

Silicon was first isolated in 1823 by J. Berzelius.

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1825

Discovery of Aluminium (Aluminum)

Al

Aluminium (aluminum), atomic number 13, has a mass of 26.982 au.

Aluminum is a silvery-white metal.

Aluminium was first isolated in 1825 by H.C.Ørsted.

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1825

Discovery of Bromine

Br

Bromine, atomic number 35, has a mass of 79.904 au.

Bromine exists as an orange diatomic molecular liquid, Br2.

Bromine was first isolated in 1825 by J. Balard and C. Löwig.

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1829

Discovery of Thorium

Th

Thorium, atomic number 90, has a mass of 232.038 au.

Radioactive element with a very long half-life.

Thorium was first observed or predicted in 1829 by J. Berzelius and first isolated in 1914 by D. Lely, Jr. and L. Hamburger.

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1830

Discovery of Vanadium

V

Vanadium, atomic number 23, has a mass of 50.942 au.

Vanadium was first observed or predicted in 1801 by M. del Río and first isolated in 1830 by N.G.Sefström.

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1838

Discovery of Lanthanum

La

Lanthanum, atomic number 57, has a mass of 138.905 au.

Lanthanum was first observed or predicted in 1838 by G. Mosander and first isolated in 1841 by G. Mosander.

Chronology of chemically the splitting of ceria (mixed oxides) into the pure rare-earth metals:

From: CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis
by Pieter Thyssen and Koen Binnemans (ISBN: 978-0-444-53590-0)

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1842

Discovery of Terbium

Tb

Terbium, atomic number 65, has a mass of 158.925 au.

Terbium was first observed or predicted in 1842 by G. Mosander and first isolated in 1886 by J.C.G. de Marignac.

Chronology of chemically the splitting of yttria (mixed oxides) into the pure rare-earth metals:

From: CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis
by Pieter Thyssen and Koen Binnemans (ISBN: 978-0-444-53590-0)

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1842

Discovery of Erbium

Er

Erbium, atomic number 68, has a mass of 167.259 au.

Erbium was first observed or predicted in 1842 by G. Mosander and first isolated in 1879 by T. Cleve.

Chronology of chemically the splitting of yttria (mixed oxides) into the pure rare-earth metals:

From: CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis
by Pieter Thyssen and Koen Binnemans (ISBN: 978-0-444-53590-0)

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1844

Discovery of Ruthenium

Ru

Ruthenium, atomic number 44, has a mass of 101.07 au.

Ruthenium was first isolated in 1844 by K. Claus.

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1860

Discovery of Cesium

Cs

Cesium (or caesium), atomic number 55, has a mass of 132.905 au.

Cesium is a Group 1 element, and these are often referred to as the "alkali metals".

Cesium was first observed or predicted in 1860 by R. Bunsen and R. Kirchhoff and first isolated in 1882 by C. Setterberg.

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1861

Discovery of Rubidium

Rb

Rubidium, atomic number 37, has a mass of 85.468 au.

Rubidium is a Group 1 element, and these are often referred to as the "alkali metals".

Rubidium was first observed, but not isolated in pure form, in 1861 by R. Bunsen and G. R. Kirchhoff.

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1861

Discovery of Thallium

Tl

Thallium, atomic number 81, has a mass of 204.384 au.

Thallium was first observed or predicted in 1861 by W. Crookes and first isolated in 1862 by C.-A. Lamy.

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1863

Discovery of Indium

In

Indium, atomic number 49, has a mass of 114.818 au.

Indium was first observed or predicted in 1863 by F. Reich and T. Richter and first isolated in 1867 by T. Richter.

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1875

Discovery of Gallium

Ga

Gallium, atomic number 31, has a mass of 69.723 au.

Gallium was first isolated in 1875 by P. E. L. de Boisbaudran.

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1878

Discovery of Ytterbium

Yb

Ytterbium, atomic number 70, has a mass of 173.054 au.

Ytterbium was first observed or predicted in 1878 by J.C.G. de Marignac and first isolated in 1906 by C. A. von Welsbach.

Chronology of chemically the splitting of yttria (mixed oxides) into the pure rare-earth metals:

From: CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis
by Pieter Thyssen and Koen Binnemans (ISBN: 978-0-444-53590-0)

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1879

Discovery of Scandium

Sc

Scandium, atomic number 21, has a mass of 44.956 au.

Scandium was first isolated in 1879 by F. Nilson.

Chronology of chemically the splitting of yttria (mixed oxides) into the pure rare-earth metals:

From: CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis
by Pieter Thyssen and Koen Binnemans (ISBN: 978-0-444-53590-0)

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1879

Discovery of Samarium

Sm

Samarium, atomic number 62, has a mass of 150.36 au.

Samarium was first isolated in 1879 by P.E.L. de Boisbaudran.

Chronology of chemically the splitting of ceria (mixed oxides) into the pure rare-earth metals:

From: CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis
by Pieter Thyssen and Koen Binnemans (ISBN: 978-0-444-53590-0)

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1879

Discovery of Holmium

Ho

Holmium, atomic number 67, has a mass of 164.93 au.

Holmium was first observed or predicted in 1878 by J.-L. Soret and first isolated in 1879 by T. Cleve.

Chronology of chemically the splitting of yttria (mixed oxides) into the pure rare-earth metals:

From: CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis
by Pieter Thyssen and Koen Binnemans (ISBN: 978-0-444-53590-0)

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1879

Discovery of Thulium

Tm

Thulium, atomic number 69, has a mass of 168.934 au.

Thulium was first isolated in 1879 by T. Cleve.

Chronology of chemically the splitting of yttria (mixed oxides) into the pure rare-earth metals:

From: CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis
by Pieter Thyssen and Koen Binnemans (ISBN: 978-0-444-53590-0)

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1880

Discovery of Gadolinium

Gd

Gadolinium, atomic number 64, has a mass of 157.25 au.

Gadolinium was first observed or predicted in 1880 by J. C. G. de Marignac and first isolated in 1886 by P.E.L. de Boisbaudran.

Chronology of chemically the splitting of ceria (mixed oxides) into the pure rare-earth metals:

From: CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis
by Pieter Thyssen and Koen Binnemans (ISBN: 978-0-444-53590-0)

Chronology of chemically the splitting of yttria (mixed oxides) into the pure rare-earth metals:

From: CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis
by Pieter Thyssen and Koen Binnemans (ISBN: 978-0-444-53590-0)

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1885

Discovery of Praseodymium

Pr

Praseodymium, atomic number 59, has a mass of 140.908 au.

Praseodymium was first isolated in 1885 by Carl Auer von Welsbach.

Chronology of chemically the splitting of ceria (mixed oxides) into the pure rare-earth metals:

From: CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis
by Pieter Thyssen and Koen Binnemans (ISBN: 978-0-444-53590-0)

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1885

Discovery of Neodymium

Nd

Neodymium, atomic number 60, has a mass of 144.242 au.

Neodymium was first isolated in 1885 by Carl Auer von Welsbach.

Chronology of chemically the splitting of ceria (mixed oxides) into the pure rare-earth metals:

From: CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis
by Pieter Thyssen and Koen Binnemans (ISBN: 978-0-444-53590-0)

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1886

Discovery of Fluorine

F

Fluorine, atomic number 9, has a mass of 18.998 au.

Fluorine exists as a pale yellow diatomic molecular gas, F2. It is the most electronegative and reactive of all elements: it which reacts with practically all organic and inorganic substances.

Fluorine was first observed or predicted in 1810 by A.-M. Ampére and first isolated in 1886 by H. Moissan.

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1886

Discovery of Germanium

Ge

Germanium, atomic number 32, has a mass of 72.63 au.

Germanium was first isolated in 1886 by C. A. Winkler.

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1886

Discovery of Dysprosium

Dy

Dysprosium, atomic number 66, has a mass of 162.5 au.

Dysprosium was first isolated in 1886 by P.E.L. de Boisbaudran.

Chronology of chemically the splitting of yttria (mixed oxides) into the pure rare-earth metals:

From: CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis
by Pieter Thyssen and Koen Binnemans (ISBN: 978-0-444-53590-0)

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1894

Discovery of Argon

Ar

Argon, atomic number 18, has a mass of 39.948 au.

Argon is a noble gas.

Argon was first isolated in 1894 by Lord Rayleigh and W. Ramsay.

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1895

Discovery of Helium

He

Helium, atomic number 2, has a mass of 4.003 au.

Helium is a noble gas, and is the second most abundant element in the universe after hydrogen.

Helium was first observed or predicted in 1868 by P. Janssen and N. Lockyer from solar spectra, and first isolated in 1895 by W. Ramsay, T. Cleve, and N. Langlet.

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1898

Discovery of Neon

Ne

Neon, atomic number 10, has a mass of 20.18 au.

Neon is a noble gas. It is present in the atmosphere, 1 part in 65000.

Neon was first isolated in 1898 by W. Ramsay and W. Travers.

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1898

Discovery of Krypton

Kr

Krypton, atomic number 36, has a mass of 83.798 au.

Krypton is a noble gas.

Krypton was first isolated in 1898 by W. Ramsay and W. Travers.

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1898

Discovery of Xenon

Xe

Xenon, atomic number 54, has a mass of 131.293 au.

Xenon is a noble gas.

Xenon was first isolated in 1898 by W. Ramsay and W. Travers.

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1898

Discovery of Polonium

Po

Polonium, atomic number 84, has a mass of 209 au.

Radioactive element.

Polonium was first observed or predicted in 1898 by P. and M. Curie and first isolated in 1902 by W. Marckwald.

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1898

Discovery of Radium

Ra

Radium, atomic number 88, has a mass of 226 au.

Radioactive element.

Radium was first observed or predicted in 1898 by P. and M. Curie and first isolated in 1902 by M. Curie.

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1899

Discovery of Radon

Rn

Radon, atomic number 86, has a mass of 222 au.

Radon is a noble gas and it is a radioactive element.

Radon was first observed or predicted in 1899 by E. Rutherford and R. B. Owens and first isolated in 1910 by W. Ramsay and R. Whytlaw-Gray.

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1901

Discovery of Europium

Eu

Europium, atomic number 63, has a mass of 151.964 au.

Europium was first observed or predicted in 1896 by E.-A. Demarçay and first isolated in 1901 by E.-A. Demarçay.

Chronology of chemically the splitting of ceria (mixed oxides) into the pure rare-earth metals:

From: CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis
by Pieter Thyssen and Koen Binnemans (ISBN: 978-0-444-53590-0)

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1902

Discovery of Actinium

Ac

Actinium, atomic number 89, has a mass of 227 au.

Radioactive element.

Actinium was first isolated in 1902 by F. O. Giesel.

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1906

Discovery of Lutetium

Lu

Lutetium, atomic number 71, has a mass of 174.967 au.

Lutetium was first isolated in 1906 by C. A. von Welsbach and G. Urbain.

Chronology of chemically the splitting of yttria (mixed oxides) into the pure rare-earth metals:

From: CRC Handbook on the Physics and Chemistry of Rare Earths, Chapter 248. Accommodation of the Rare Earths in the Periodic Table: A Historical Analysis
by Pieter Thyssen and Koen Binnemans (ISBN: 978-0-444-53590-0)

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1913

Discovery of Protactinium

Pa

Protactinium, atomic number 91, has a mass of 231.036 au.

Radioactive element: Pa is only found in tiny amounts in nature. Most samples are synthetic.

Protactinium was first observed or predicted in 1913 by O. H. Göhring and K. Fajans and first isolated in 1927 by A. von Grosse.

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1919

Discovery of Rhenium

Re

Rhenium, atomic number 75, has a mass of 186.207 au.

Rhenium was first observed or predicted in 1908 by M. Ogawa and first isolated in 1919 by M. Ogawa.

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1922

Discovery of Hafnium

Hf

Hafnium, atomic number 72, has a mass of 178.49 au.

Hafnium was first isolated in 1922 by D. Coster and G. von Hevesy.

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1937

Discovery of Technetium

Tc

Technetium, atomic number 43, has a mass of 98 au.

Radioactive element: Tc is only found in tiny amounts in nature. Most samples are synthetic.

Technetium was first isolated in 1937 by C. Perrier and E. Segrè. The element had been predicted by Mendeleev in 1871 as eka-manganese.

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1939

Discovery of Francium

Fr

Francium, atomic number 87, has a mass of 223 au.

Radioactive element.

Francium was first observed in 1939 by M. Perey.

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1940

Discovery of Astatine

At

Astatine, atomic number 85, has a mass of 210 au.

Radioactive element.

Astatine was first observed or predicted in 1940 by R. Corson, R. MacKenzie and E. Segrè.

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1940

Discovery of Neptunium

Np

Neptunium, atomic number 93, has a mass of 237 au.

Radioactive element: Np is only found in tiny amounts in nature. Most samples are synthetic.

Neptunium was first observed in 1940 by E.M. McMillan and H. Abelson.

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1940

Discovery of Plutonium

Pu

Plutonium, atomic number 94, has a mass of 244 au.

Radioactive element: Pu is only found in tiny amounts in nature. Most samples are synthetic.

Plutonium was first observed in 1940 by Glenn T. Seaborg, Arthur C. Wahl, W. Kennedy and E.M. McMillan.

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1944

Discovery of Americium

Am

Americium, atomic number 95, has a mass of 243 au.

Synthetic radioactive element. It is used in smoke detectors, and so – surprisingly – is present most houses and buildings.

Americium was first observed in 1944 by G. T. Seaborg, R. A. James, O. Morgan and A. Ghiorso.

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1944

Discovery of Curium

Cm

Curium, atomic number 96, has a mass of 247 au.

Synthetic radioactive element.

Curium was first observed in 1944 by G. T. Seaborg, R. A. James and A. Ghiorso.

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1945

Discovery of Promethium

Pm

Promethium, atomic number 61, has a mass of 145 au.

Radioactive element: Pm is only found in tiny amounts in nature. Most samples are synthetic.

Promethium was first observed or predicted in 1942 by S. Wu, E.G. Segrè and H. Bethe and first isolated in 1945 by Charles D. Coryell, Jacob A. Marinsky, Lawrence E. Glendenin, and Harold G. Richter.

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1949

Discovery of Berkelium

Bk

Berkelium, atomic number 97, has a mass of 247 au.

Synthetic radioactive element.

Berkelium was first observed in 1949 by G. Thompson, A. Ghiorso and G. T. Seaborg.

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1950

Discovery of Californium

Cf

Californium, atomic number 98, has a mass of 251 au.

Synthetic radioactive element.

Californium was first observed in 1950 by S. G. Thompson, K. Street, Jr., A. Ghiorso and G. T. Seaborg.

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1952

Discovery of Einsteinium

Es

Einsteinium, atomic number 99, has a mass of 252 au.

Synthetic radioactive element.

Einsteinium was first observed in 1952 by A. Ghiorso et al.

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1952

Discovery of Fermium

Fm

Fermium, atomic number 100, has a mass of 257 au.

Synthetic radioactive element.

Fermium was first observed in 1952 by A. Ghiorso et al.

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1955

Discovery of Mendelevium

Md

Mendelevium, atomic number 101, has a mass of 258 au.

Synthetic radioactive element.

Mendelevium was first observed in 1955 by A. Ghiorso, G. Harvey, R. Choppin, S. G. Thompson and G. T. Seaborg.

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1955

Element Hunters

A YouTube video, The Element Hunters.

The text accompanying the video says:

"Scientist in Berkeley discover new elements [Californium & Einsteinium] from hydrogen bomb debris in 1951 and then use the 60 inch Cyclotron to create Mendelevium, element 101. The team included Nobel Prize winner Glenn Seaborg and famed element hunter, Albert Ghiorso."


Thanks to Roy Alexander for the tip! 

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1961

Discovery of Lawrencium

Lr

Lawrencium, atomic number 103, has a mass of 262 au.

Synthetic radioactive element.

Lawrencium was first observed in 1961 by A. Ghiorso, T. Sikkeland, E. Larsh and M. Latimer.

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1966

Discovery of Nobelium

No

Nobelium, atomic number 102, has a mass of 259 au.

Synthetic radioactive element.

Nobelium was first observed in 1966 by E. D. Donets, V. A. Shchegolev and V. A. Ermakov.

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1969

Discovery of Rutherfordium

Rf

Rutherfordium, atomic number 104, has a mass of 267 au.

Synthetic radioactive element.

Rutherfordium was first observed in 1969 by A. Ghiorso et al. and I. Zvara et al.

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1970

Discovery of Dubnium

Db

Dubnium, atomic number 105, has a mass of 268 au.

Synthetic radioactive element.

Dubnium was first observed in 1970 by A. Ghiorso et al. and V. A. Druin et al.

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1974

Discovery of Seaborgium

Sg

Seaborgium, atomic number 106, has a mass of 271 au.

Synthetic radioactive element.

Seaborgium was first observed in 1974 by A. Ghiorso et al.

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1981

Discovery of Bohrium

Bh

Bohrium, atomic number 107, has a mass of 272 au.

Synthetic radioactive element.

Bohrium was first observed in 1981 by G.Münzenberget al.

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1982

Discovery of Meitnerium

Mt

Meitnerium, atomic number 109, has a mass of 276 au.

Synthetic radioactive element.

Meitnerium was first observed in 1982 by G. Münzenberg, P. Armbrusteret al.

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1984

Discovery of Hassium

Hs

Hassium, atomic number 108, has a mass of 270 au.

Synthetic radioactive element.

Hassium was first observed in 1984 by G. Münzenberg, P. Armbruster et al.

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1994

Discovery of Darmstadtium

Ds

Darmstadtium, atomic number 110, has a mass of 281 au.

Synthetic radioactive element.

Darmstadtium was first observed in 1994 by S. Hofmann et al.

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1994

Discovery of Roentgenium

Rg

Roentgentium, atomic number 111, has a mass of 280 au.

Synthetic radioactive element.

Roentgenium was first observed in 1994 by S. Hofmann et al.

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1996

Discovery of Copernicium

Cn

Copernicum, atomic number 112, has a mass of 285 au.

Synthetic radioactive element.

Copernicium was first observed in 1996 by S. Hofmann et al.

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1999

Discovery of Flerovium

Fl

Flerovium, atomic number 114, has a mass of 289 au.

Synthetic radioactive element.

Flerovium was first observed in 1999 by Y. Oganessianet et al.

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2000

Discovery of Livermorium

Lv

Livermorium, atomic number 116, has a mass of 293 au.

Synthetic radioactive element.

Livermorium was first observed in 2000 by Y. Oganessian et al.

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2002

Discovery of Oganesson

Og

Oganesson, atomic number 118, has a mass of 294 au.

Synthetic radioactive element.

Oganesson was first observed in 2002 by Y. Oganessian et al.

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2003

Discovery of Nihonium

Nh

Nihonium, atomic number 113, has a mass of 284 au.

Synthetic radioactive element.

Nihonium was first observed in 2003 by Y. Oganessian et al. and K. Morita et al.

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2003

Discovery of Moscovium

Mc

Moscovium, atomic number 115, has a mass of 288 au.

Synthetic radioactive element.

Moscovium was first observed in 2003 by Y. Oganessian et al.

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2010

Discovery of Tennessine

Ts

Tennessine, atomic number 117, has a mass of 292 au.

Synthetic radioactive element.

Tennessine was first observed in 2010 by Y. Oganessian et al.

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What is the Periodic Table Showing? Periodicity

© Mark R. Leach Ph.D. 1999 –


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