Does a Relationship Exist between the Reactivity of a Metal & When it was Discovered? Isha Lamba 8B Science To answer this question let’s examine some facts and historical information. Majority of the known elements are metals. Majority of the known elements are metals. Today mankind knows of 86 metals out of a total of 112 elements. The first two metals to be discovered were gold and copper. We have learnt that different important metals can be arranged in the order of their decreasing reactivity as: K Na Ca Mg Al Zn Fe Pb Cu Ag Hg Au And here is the timeline representing the discovery of different metals included in this reactivity series… However, a more comprehensive list can be recognized as:- And here is the information about the dates of discovery for each of these metals Discovered Metal K Na Li Sr Ca Mg Al Zn Cr Fe Cd Co Ni Sn Pb Cu Ag Hg Au Pt Year 1807 1807 1817 1790 1808 1808 1825 1746 1797 -1500 1817 1737 1751 -1750 -3500 -4200 -4000 -750 -6000 1735 The First Metal to be Discovered - Gold Gold has been used since 6000 BC Gold is virtually placed at the bottom of the Reactivity series. Gold came into use the first because of some special properties… Gold – Facts: Shining Yellow Color: The symbol for gold is Au, which represents abbreviated form of the Latin word – ‘Aurum’, meaning ‘shining dawn’. In case of the earliest metals, their color was a very important property as this is what allowed the metals to be recognized in the surrounding rock, stones, gravel and dirt (and evoked interest) as well as enabled their separation from them in the earliest days. Gold is found uncombined in nature >> this fact also helped its discovery and subsequent use. Gold is virtually noncorrosive and tarnish free (as it does not get oxidized) >> this made it attractive to man. All these facts and properties of Gold are related to (and can be explained based on) the lack of reactivity of Gold. The Next Metal to be Used by Man: Copper Copper was discovered in 4200 BC The first metallic tools, implements and weapons were made from copper. Copper also is found free besides also being found in the form of minerals like cuprite, malachite, azurite, chalcopyrite and bornite. In the Reactivity-Series (in the order of reactivity) Copper again comes in the bottom block (amongst the elements with low reactivity) Until the end of the 17th century (and for a large span of some 7700 years), only 12 metals were known. Gold Tin Silver Platinum Copper Antimony Lead Bismuth Mercury Zinc Iron Arsenic Seven out of these twelve metals were the metals upon which the ancient civilizations were based. They were: Gold (discovered in 6000BC) Copper (discovered in 4200BC) Silver (discovered in 4000BC Lead (discovered in 3500BC) Tin (discovered in 1750BC) Iron (discovered in 1500BC) Mercury (discovered in 750BC) So, these metals are known as Metals of Antiquity. All of them find a place in the lower part of the reactivity series (with the exception of Iron that is towards the middle of the series). The other four of these twelve metals - arsenic, antimony, zinc and bismuth, were discovered in the thirteenth and fourteenth centuries. Arsenic, antimony and bismuth are not shown in the reactivity series but Zinc is included in the reactivity series and occupies a place just a little higher than Iron (appropriately). Platinum which was discovered in the 16th century – so far forms the only big exception from the trend (the lower the reactivity of the metal, the earlier was it discovered). The next 12 metals were discovered in the 18th Century Cobalt (1735) Uranium (1789) Nickel (1751) Zirconium (1789) Manganese (1774) Titanium (1791) Molybdenum (1781) Yttrium (1794) Tellurium (1782) Beryllium (1797) Tungsten (1783) Chromium (1797) These metals again appear at appropriate place in the reactivity series, with respect to the trend – the lower the reactivity of the metal, the earlier it was discovered. The 41 metals that were discovered in 19th Century include: Niobium (1801), Tantalum (1802), Iridium (1803), Palladium(1803), Rhodium (1803), Potassium (1807), Sodium (1807), Boron (1808), Barium (1808), Calcium (1808), Magnesium (1808), Strontium (1808), Cerium (1814), Lithium (1817), Cadmium (1817), Selenium (1817), Silicon (1823), Aluminum (1827), Thorium (1828), Vanadium (1830), Lanthanum (1839), Erbium (1843), Terbium (1843), Ruthenium (1844), Cesium (1860), Rubidium (1860), Thallium (1861), Indium (1863), Gallium (1875), Holmium, Thulium, Scandium, Samarium, Gadalinium, Praseodynium, Neodynium and Dysprosium (1878-1885), Germanium (1886), Polonium (1898), Radium (1898) Actinium (1899) These 41 metals include metals like Potassium, Sodium, Calcium, Magnesium and Aluminum which show on the top of the reactivity series. Some of the elements discovered in the later part of this century are members of Lanthanide and Actinide series – both of which are known to be very reactive (and electropositive). Metals Discovered in the 20th Century Europium (1901), Lutetium (1907), Protactinium (1917), Hafnium (1923), Rhenium (1924), Technetium (1937), Francium (1939), Promethium (1945), Transuranium elements - Neptunium, Plutonium, Curium, Americum, Berkelium, Californium, Einsteinium, Fermium, Mendelevium, Nobelium, Lawrencium (1940-61) More members of Lanthanide and Actinide series get discovered – both of which are known to be very reactive (and electropositive). Relationship of the discovery time with the position in the reactivity series Discovery of Elements as arranged in the order of their increasing Reactivity 2000 1000 0 -1000 -2000 -3000 Pt Au Hg -4000 Ag Cu Pb Sn Ni -5000 Co Cd Fe Cr Zn Al Mg Ca -6000 Discovered Element Sr Li Na K So the observations suggest a strong trend – that the lesser the reactivity of a metal, the earlier was its discovery and conversely the more the reactivity of a metal, the later was its discovery. Conclusion From the scientific logic, a metal that was reactive was expected to be occurring in a combined state (in form of its compounds with other elements), posing a challenge for its extraction from the ores and needing extra effort both in form of man’s ability and his knowledge. And as the reactivity of the metal increased, the level of this challenge also increased. Naturally with man’s ability having evolved over the years, he was able to discover the more and more difficult (from extraction point of view) metals (that were actually more and more reactive metals) as well as find their virtues and applications. Conclusion The trend does not have to be followed strictly by each and every metal in relation to each and every metal adjacent to it, since there may have been certain other determining factors also (including the chance factor), besides the effect of this strong scientific factor. But generally if we consider the metals arranged in the reactivity-series in form of chunks, then this trend was more or less observed everywhere with the exception of Platinum (which got discovered too late), Mercury (which got discovered a bit late) and Iron (which got discovered a bit too early for the trend). BIBLIOGRAPHY Petrucci, Ralph H.. General chemistry: principles and modern applications. 10th ed. Toronto: Pearson Prentice Hall, 2010. Print. Nile, 3600 BC the first copper smelted artifacts were found in the. "History of Metals ."Department of Materials Science & Engineering . N.p., n.d. Web. 10 Nov. 2010. <http://neon.mems.cmu.edu/cramb/Processing/history.html>. "Metals Timeline Card Sort KFB – Resources - TES Connect ."TES Connect -Teaching Jobs, Teaching Resources & Community . N.p., n.d. Web. 10 Nov. 2010. <http://www.tes.co.uk/ResourceDetail.aspx?storyCode=6024085>. "Metals timeline."www.ic.arizona.edu. N.p., n.d. Web. 10 Nov. 2010. <http://www.ic.arizona.edu/ic/mse257/class_notes/metals_timeline.html>. “Rare Earth Metals May Trigger Trade Wars : Discovery News."Discovery News: Earth, Space, Tech, Animals, Dinosaurs, History . N.p., n.d. Web. 10 Nov. 2010. <http://news.discovery.com/earth/rare-earth-metals-trade-wars.html>. "Chemical Elements.com - Discovery Date." Chemical Elements.com - An Interactive Periodic Table of the Elements. N.p., n.d. Web. 10 Nov. 2010. <http://www.chemicalelements.com/show/dateofdiscovery.html>.