After Newland’s attempt The Russian chemist Dmitri Ivanovich Mendeleev (below) produced a better version of the periodic table (left). He became convinced that groups of elements had similar, "periodic" properties. Elements on Mendeleev table were arranged according to their increasing atomic mass, leaving blank spaces where he was sure other, unknown elements would fit. He was bold enough to predict the properties of these unknown elements based on the idea of periodic properties. As he predicted three of the five elements have been discovered. The advantage of Mendeleev table over previous attempts was that it showed similarities in an entire network of vertical, horizontal, and diagonal relationships.
Gallium is the only metal except for mercury caesium and rubidium which can be liquid near room temperature. This makes its use for high temperature thermometers. It has the longest liquid range of any metal and has a low vapour pressure even at high temperatures. The physical properties of gallium are considered to be unusual because the fact that is a solid at 298 K but melts only slightly above this temperature and it is this property suggests that is a metal. Another property that considers gallium to unusual is that it has a high boiling point of 2403˚c and a low melting point. Another property of gallium that makes it unusual is that it shares with water the property of being denser as a liquid than as a solid from the top down. This suggestion can be applied to that of ice and water, and sets gallium apart as a non metal. Like aluminium the metal above it in the periodic table, gallium shares a lot of similar properties.
Like aluminium gallium reacts with hydrogen ions.
2A(S) = 6H (aq) 2AL (aq) = 3H2 (g)
2Ga (s) +6H 2 Ga (aq) + 3 H2
They also form similar reactions with each other with hydroxide ions
2Al(s) + 2OH (aq) + 6H2O (I) 2(Al (OH) 4) (aq) +3H2 (g)
2Ga(s) + 2OH (aq) + 6H2O (I) 2(Ga (OH) 4) (aq) = 3H2 (g)
Only a select amount of metals act likes this and it is these kinds of metals show basic acidic properties because they react with both alkalis and acids.
The atomic spectroscopy and UNILAC accelerator are ways of synthesising elements. The modern day periodic table is classified not only by increasing atomic mass but also increasing atomic number. The atomic spectroscopy and UNILAC have made it possible to identify these. Unknown elements can be identified by the atomic spectroscopy and UNILAC accelerator because their atomic masses can be measured. From this it can be compared to other elements and judgement can be made on their chemical and physical properties. This can determine what element it is and how it can be used and where it should go in the periodic table. The UNILAC accelerator can be to synthesise elements and compound. The nuclei of the elements can fuse together to make new elements. The way it is done is by firing ion at a rotating disc of the metal target. The new elements are separated and checked.
The role of chemist plays a big part in everyday life. Over the past two hundred years their role has gradually increased. It started off with the discovery of elements. Then an appropriate way had to be devised for them to be classified hence the modern day periodic table that we now see. Then the search continued to discover new elements. More and more elements were found chemists, and scientist considered using it commercially, such as the manufacturing of food, health beauty products, fuels etc. The role of chemist have also become more important due to the fact that they can give an explanation of what is happening in our atmosphere, how it caused and how to reduce it e.g. global warming. Therefore the work and role of chemists is increasing and in becoming more valuable.
