Periodic Table Of The Elements example essay topic

Chemistry November 18, 2002 The Periodic Table of Elements In September 1860 the birth of the Periodic table began. A group of the world's best chemists assembled in Germany to discuses the issues of atomic mass. At this meeting an Italian chemist, Stanislao Cannizzaro, introduced the right way to accurately measure the relative mass of an atom. After the new method was introduced chemists started to recognize similarities in the properties of various elements and placed them into families. In this earlier stages of the periodic table there were four main chemists; Dobereiner, Newlands, Lothar Meyer, and Dmitri Mendeleev that played a substantial role in the development of the periodic table. Dobereiner started with a few family groups each containing three elements.

Newlands put the elements of those families in repeating groups called octaves. Meyer noted additional repeating properties. Mendeleev put it all together into what has become the periodic table of the elements. The German chemist, named Dobereiner, in 1829 noted some of the first elemental similarities.

His observations began with bromine, which had just been discovered. He noticed that the properties of bromine were similar to chlorine and iodine. Not only were they related but also various properties of bromine, including the atomic weight, fell midway between the properties of chlorine and iodine, but also there was a pattern within the group of regularly increasing atomic weights. As he did his research he noticed a couple other groups of elements with patterns like this. He described these groups as being triads, groups of three elements that had similar properties. Not much was made of this because the triads only covered one-sixths of the known elements.

Most chemists of the time considered them to be a coincidence. Somewhat later, about 1864, a chemist by the name of Newlands came up with what he called the "law of octaves". This idea was a bit more developed than Dobereiner's triads. Newlands arranged the known elements by atomic weights. While doing this he noticed some recurring patterns, and he broke up his list of elements into groups of seven starting a new row with the eighth element.

The first elements in each of those groups were similar to one another, and so was the second element, the third and so on. There was a certain pattern in the properties of elements that became even more apparent as time went on. In the 1860's quite a bit of new information developed. In no small part this was due to the ideas of Avogadro championed by Stanislao Cannizarro.

In 1870, Lothar Meyer, a German chemist, made a chart that plotted atomic volumes against atomic weight. He measured the volume of one atomic weight's worth of each element, one mole, and figured that since the number of atoms in each amount was the same. The volumes measured must represent the relative volumes of the individual atoms. An important observation that Meyer made was the change in length of that repeating pattern.

Unlike Newslands' octaves, these groups were not all the same length. Hydrogen was sort of a group all by itself. A Russian chemist, Dmitri Mendeleev, did the most famous work that was done in developing the periodic table. Mendeleev developed his periodic table in 1869. It was a table, not a graph. It was a two-dimensional arrangement in which elements having similar properties were placed adjacent to one another.

It took several different appearances as it was developed. He began by lining up the elements in order of their atomic weights, just as Meyer was doing at about the same time. His first published tables listed the elements vertically. Later he published a horizontal table. Mendeleev incorporated three very important features. Like Newlands he started a new line when the elemental properties repeated themselves.

Later when more was known about atomic structure and electron configurations, we found out that those electron configurations could also be related to the shape of the periodic table. This also shows that the chemical properties were related to the electron configuration. Another Great Chemist, Glenn Seaborg, added a great deal to the periodic table. Glenn was a very dedicated scientist and was noted to stay up all night working the "Graveyard shift". In the cave room were he worked he was involved in the discovery of elements 93 through 102, a task that required lots of dedicated hard work. These elements are today known as neptunium, plutonium, mendelevium, americium, curium, berkelium, californium, einsteinium, fermium, and nobelium.

Because of his extensive knowledge of radioactive materials he was added to the team of scientist that participated in the Manhattan Project. Which was the race to produce the atomic bomb. There were many great chemists that were involved in the making of the periodic table. It was a long and changing process. Even still to this day the periodic table changes and evolves as different elements are discovered.