1. The elements of life EL3 Looking for patterns in elements

2. When elements were being discovered, and more was being learned chemists looked for patterns in the information they had assembled We have seen close similarities between Ca and Sr, Magnesium (Mg) and Barium (Ba) can be added to make a group of four elements You probably know info about two other groups Gp 1 (Li, Na, K) and Group7 (F, Cl, Br and I)

3. Looking for patterns in elements 59 of the 92 naturally occurring elements had been discovered by 1850 – the search for patterns in the elements were particularly fruitful around this time Much of the work was done by – Johann Döbereiner and Lother Mayer in Germany, John Newlands in England and Dimitri Mendeleev in Russia Mendeleev Döbereiner NewlandsMayer

4. Looking for patterns in elements- Newlands Reactions to their suggestions were not always favourable Some of the symbols look unfamiliar G is now Be Bo is now B Ro is now Rh By 1897 it had been established that Di was not an element, but a mixture of two closely related elements

5. Looking for patterns in elements-Mendeleev 3 years after Newlands, Mendeleev’s groupings were much more credible. Elements were arranged in order of increasing atomic masses, so that elements with similar properties came in the same vertical groups

6. Looking for patterns in elements-Mendeleev Mendeleev left gaps in his table. Gaps were very important, they allowed the discovery of new elements Mendeleev made predictions about elements which had yet to be discovered. 1871, he predicted the properties of an element he called eka-silicon which he was confident that would be discovered to fill the gap between silicon and tin.

7. Looking for patterns in elements-Mendeleev The element was discovered 15 years later and named germanium, its properties were almost exactly as he had predicted Since Mendeleev death in 1907, 8 elements have been discovered and 24 have been made in the lab

8. Looking for patterns in elements-Mendeleev The first two elements to be made in the lab were neptunium (z = 93) and plutonium (z=94) these were made by bombarding uranium atoms with neutrons. By 1961 elements up to z= 103 had been made By 2000 there were twelve more up to z =118 Glen Seaborg Glen Seaborg awarded the 1951 Nobel Prize in Chemistry. He was co- discover of Plutonium and lead the Manhattan Project's chemical process for the separation, concentration and isolation of plutonium

9. Looking for patterns in elements The modern periodic table is based on the one originally drawn up by Mendeleev. It is one of the most amazingly compact stores of information ever produced!