Discovering the Periodic Table Ne Ar Kr Xe Po Rn Ra Eu Lu Pa Ac 1894-1918 C S Fe Cu Ag Sn Au Hg Pb Ancient Times Cr Mn Li K N O F Na B Be H Al Si Cl Ca Ti V Co Ni Se Br Sr Y Zr Nb Mo Rh Pd Cd Te I Ba Ta W Os Ir Mg Ce Tb Er Th U P Zn As Sb Pt Bi Midd. -1700 1735-1843 Tc Hf Re At Fr Pm Np Pu Am Cm Bk Cf Es Fm Md No Lr 1923-1961 He Sc Ga Ge Rb Ru In Cs Tl Pr Nd Sm Gd Dy Ho Tm Yb La 1843-1886 Rf Db Sg Bh Hs Mt 1965- 30 elements had been isolated and identified 1870 60 known elements The Noble Gases At the start of the 1890s, no one had any idea that there was a separate group of gases in the periodic table, the noble gases. Noble gases are familiar to us from their use in neon signs and helium balloons. By 1900 this whole new group had been identified and isolated. While trying to determine an accurate atomic mass for nitrogen, British physicist Lord Raleigh (1842-1919) discovered that nitrogen prepared from ammonia was noticeably lighter than nitrogen that came from the atmosphere. He and William Ramsay (1852-1916) both studied “atmospheric” nitrogen. By removing the nitrogen from it, they produced a tiny quantity of another gas. Since it did not react with anything they called it argon, from the Greek word for lazy. The discovery of helium followed a year later in 1895. Ramsay and his assistant Morris Travers (1872-1961) then started to search for additional elements in this new group. They attempted this by fractional distillation of large quantities of liquid air and argon. In 1898, their efforts were rewarded; they had prepared krypton, neon, and xenon. Eyewitness Science “Chemistry” , Dr. Ann Newmark, DK Publishing, Inc., 1993, pg 32 Timeline of Elements Discovery Journal of Chemical Education, Sept. 1989

Discovering the Periodic Table Ne Ar Kr Xe Po Rn Ra Eu Lu Pa Ac 1894-1918 C S Fe Cu Ag Sn Au Hg Pb Ancient Times Cr Mn Li K N O F Na B Be H Al Si Cl Ca Ti V Co Ni Se Br Sr Y Zr Nb Mo Rh Pd Cd Te I Ba Ta W Os Ir Mg Ce Tb Er Th U P Zn As Sb Pt Bi Midd. -1700 1735-1843 Tc Hf Re At Fr Pm Np Pu Am Cm Bk Cf Es Fm Md No Lr 1923-1961 He Sc Ga Ge Rb Ru In Cs Tl Pr Nd Sm Gd Dy Ho Tm Yb La 1843-1886 Rf Db Sg Bh Hs Mt 1965- The Noble Gases At the start of the 1890s, no one had any idea that there was a separate group of gases in the periodic table, the noble gases. Noble gases are familiar to us from their use in neon signs and helium balloons. By 1900 this whole new group had been identified and isolated. While trying to determine an accurate atomic mass for nitrogen, British physicist Lord Raleigh (1842-1919) discovered that nitrogen prepared from ammonia was noticeably lighter than nitrogen that came from the atmosphere. He and William Ramsay (1852-1916) both studied “atmospheric” nitrogen. By removing the nitrogen from it, they produced a tiny quantity of another gas. Since it did not react with anything they called it argon, from the Greek word for lazy. The discovery of helium followed a year later in 1895. Ramsay and his assistant Morris Travers (1872-1961) then started to search for additional elements in this new group. They attempted this by fractional distillation of large quantities of liquid air and argon. In 1898, their efforts were rewarded; they had prepared krypton, neon, and xenon. Eyewitness Science “Chemistry” , Dr. Ann Newmark, DK Publishing, Inc., 1993, pg 32 Journal of Chemical Education, Sept. 1989

Discovering the Periodic Table Ne Ar Kr Xe Po Rn Ra Eu Lu Pa Ac 1894-1918 C S Fe Cu Ag Sn Au Hg Pb Ancient Times Tc Hf Re At Fr Pm Np Pu Am Cm Bk Cf Es Fm Md No Lr 1923-1961 He Sc Ga Ge Rb Ru In Cs Tl Pr Nd Sm Gd Dy Ho Tm Yb La 1843-1886 Cr Mn Li K N O F Na B Be H Al Si Cl Ca Ti V Co Ni Se Br Sr Y Zr Nb Mo Rh Pd Cd Te I Ba Ta W Os Ir Mg Ce Tb Er Th U 1735-1843 P Zn As Sb Pt Bi Midd. -1700 Rf Db Sg Bh Hs Mt 1965- The Noble Gases At the start of the 1890s, no one had any idea that there was a separate group of gases in the periodic table, the noble gases. Noble gases are familiar to us from their use in neon signs and helium balloons. By 1900 this whole new group had been identified and isolated. While trying to determine an accurate atomic mass for nitrogen, British physicist Lord Raleigh (1842-1919) discovered that nitrogen prepared from ammonia was noticeably lighter than nitrogen that came from the atmosphere. He and William Ramsay (1852-1916) both studied “atmospheric” nitrogen. By removing the nitrogen from it, they produced a tiny quantity of another gas. Since it did not react with anything they called it argon, from the Greek word for lazy. The discovery of helium followed a year later in 1895. Ramsay and his assistant Morris Travers (1872-1961) then started to search for additional elements in this new group. They attempted this by fractional distillation of large quantities of liquid air and argon. In 1898, their efforts were rewarded; they had prepared krypton, neon, and xenon. Eyewitness Science “Chemistry” , Dr. Ann Newmark, DK Publishing, Inc., 1993, pg 32 Journal of Chemical Education, Sept. 1989

$ Symbols are Useful c . + - x . The use of symbols is not unique to chemistry. Symbols can be quite helpful - when you know what they mean. Arithmetic Money Music $ . c + - x . “A tidy laboratory means a lazy chemist.” -- Jöns Jacob Berzelius (Swedish chemist,1779-1848) Image: http://www.sil.si.edu/digitalcollections/hst/scientific-identity/fullsize/SIL14-B3-14a.jpg A Swedish chemist who invented modern chemical symbols. Discovered the elements: silicon, selenium, cerium, and thorium. Jons Jakob Berzelius (1799 - 1848)

Discovering the Elements Metal gold silver iron mercury tin copper lead Symbol Celestial body Sun Moon Mars Mercury Jupiter Venus Saturn Day Latin (dies) Solie Lunae Martis Mercurii Jovis Veneris Saturni French dimanche lundi mardi mercredi jeudi vendredi samedi English Sunday Monday Tuesday Wednesday Thursday Friday Saturday Ringnes, Journal of Chemical Education, Sept. 1989, page 731

Chemical Symbols Symbols used in the 16th and 17th Century Gold Silver Iron Copper Lead Tin Mercury Sun Moon Mars Venus Saturn Jupiter Mercury Ancient Astronomical Symbols Alchemical Symbols used in the 15th Century Fire Air Earth Water Brownlee, Fuller, Hancock, Sohon, Whitsit, First Principles of Chemistry, 1931, page 74

Chemical Symbols Symbols used in the 18th Century Antimony Water Sulfuric acid Copper Sulfur Symbols used by John Dalton Carbon Hydrogen Oxygen Silver Sulfur Nitrogen S Lead Mercury Copper C L Gold Potassa Soda G Water Carbon dioxide Alcohol Brownlee, Fuller, Hancock, Sohon, Whitsit, First Principles of Chemistry, 1931, page 74