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The nineteenth century was the golden age for the discovery of elements.

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Introduction

"The nineteenth century was the golden age for the discovery of elements. Scientists began to look for patterns of behaviour between elements."*1 Johann D�bereiner, a German chemist, was the first to attempt to categorise the elements. He used their atomic weights, which we now know as atomic masses. In 1863, John Newlands, produced something that he called the 'Law of Octaves'. He used this to produce his own version of the periodic table, but Newlands came across some problems. "After about 20 elements his table became ragged,"*2 Newlands had left no gaps for undiscovered elements and even had to put two elements in one space. It was Dimitri Mendeleev, a Russian chemistry professor, in 1869 that produced a much improved table. He amended many of the atomic weight values and left gaps for undiscovered elements. "Mendeleev was so confident of the basis upon which he had drawn up his table that he made predictions about elements which had yet to be discovered."*3 Since Mendeleev's table all the gaps he left have been filled, three of the five elements whose properties he predicted were found within fifteen years, and a whole new group has been introduced - the Noble Gases. ...read more.

Middle

Gallium has some very unusual properties, some which suggest that it is a metal and some that imply it is a non-metal. Its physical properties, a melting point of 29.78�C (which is almost UK room temperature) making it a liquid metal along with Mercury and Caesium. It also has an extremely high boiling point, 2403�C; together with its low boiling point gallium has the 'widest liquid range' of any element discovered so far. Gallium is also denser as a liquid than as a solid, as is water. Gallium's chemical properties include, dissolving in acid and alkalis, evolving hydrogen. Aluminium and gallium both have the same reaction when mixed with hydrogen ions. *8Reaction between aluminium and hydrogen ions 2Al(s) + 6H (aq) 2Al (aq) + 3H (g) Reaction between gallium and hydrogen ions 2Ga(s) + 6H(aq) 2Ga (aq) + 3H (g) The same happens in the reaction with gallium and hydroxide ions; Gallium and hydroxide ions 2Ga(s) + 2OH (aq) + H2O(l) 2[Ga(OH) ] (aq) + 3H (g) ...read more.

Conclusion

This resulted in the creation of element 107 - bohrium. Cr + Bi element *13 The GSI formed four more elements over the following years; the most recent was February 1996, they fired zinc ions at a lead metal target, creating element 112 - ununbium. Zn + Pb element *14 In the nineteenth century atomic spectroscopy was used commonly by scientists to discover new elements over 140 years of Mendeleev's periodic table three of his predicted elements were discovered, eka-aluminium, eka-boron and eka-silicon. 1875 - Paul Emile Lecoq de Boisbaudran discovered germanium, (eka-aluminium), 1881 - Lars Nilson found scandium, (eka-boron), 1886 Clemens Winkler found germanium, (eka-silicon). Since then the UNILAC accelerator was introduced. "There are 92 naturally occurring chemical elements"*15 from hydrogen to uranium. Scientists have gone beyond uranium by purposely synthesising 'artificial' elements; this is achieved using the UNILAC accelerator. This involves firing beams of metal ions into a rotating metal target with greater force, the nuclei of the atoms fuse together creating a new element. In 1940, Ed McMillan created the first artificial element - Neptunium. Over the 25 years Glenn Seabory, of the University of California at Berkeley discovered an entire family of new elements, 94 to 102. ...read more.

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