Virtually all science classrooms will have at least one common thing posted on their walls; a poster of the periodic table. The periodic table is simply a chart of all known elements, arranging them as defined by periodic law; it orders the elements by increasing atomic number, displaying the periodicity of chemical and physical properties in the elements. The first contributions to the periodic table were made in antiquity, with the discovery of obvious elements such as gold, silver, tin, copper, lead and mercury. In 1649, the first scientific discovery of an element occurred in 1649 when Hennig Brand discovered phosphorous. Many other elements were later discovered; a total of 63 elements existed by 1869. By observing the growing list of elements, scientists were able to observe patterns in properties, beginning to develop schemes for classification. The chart used today arranges the elements by increasing atomic number. Each element in the table is represented by its appropriate chemical symbol, along with its atomic number, atomic weight, and electron configuration.
Sometimes, more complex tables contain the element's atomic diameter/radius, common valence numbers or oxidation states, melting/boiling point, density, specific heat, stable/radioactive isotopes, type of magnetism, and other details about each element. This chart is often referred to within the classroom; in fact, it is essential to modern day science. Through the work of numerous scientists throughout history this important table exists today.
The French geologist A.E. BÃÂ©guyer de Chancourtois is credited with creating the first ordering of the elements demonstrating their periodicity, published in 1862. De Chancourtois made a list of all the elements in order of increasing atomic mass and arranged them on a cylinder- which he called the telluric helix- where exactly 16 mass units could be written per turn, so that closely related elements lined up in vertical...
The Periodic Table Essay
The Periodic Tablea)i)name of the element: oxygenii) Symbol: Oiii) Atomic number: 8iv) Mass number: 15.9994 amuv) Number of neutrons: 8vi) Electron configuration:vii) Appearance:viii) Melting point: -218.4°C boiling point: -183.0°Cix) Density: 1.429g/cm³x) Valencies:2xi) Uses of the element: without oxygen, there would be no life on this earth because oxygen is one of the necessities for life on this planet.
xii) Brief outline of its discovery: it was discovered in 1774 by Joseph Priestly. It was obtained from liquid air. The name comes from the Greek words 'oxus' which means acid, and 'gennen' which means generate.
b) Briefly outline the development of the periodic table focusing on the contributions made by Mendeleev.
The periodic table is a very important source of information for many around the world for it is the organisation of all of the known elements. The table is very useful because it is easy to read information from once you are able to understand how it is arranged.
Long ago, there was no need for the periodic table for they did not understand the world around them. Though when phosphorus was discovered by Hennig Brand, from preparing it from urine, an immense amount of information about compounds and elements were discovered during the time after that. When more and more elements and compounds were being discovered, scientists found the need to organise that information of easy access and use for future use. To organise the information they had collected they found patterns which was found throughout their discoveries as a foundation to arrange them.
Johann Dobereiner was a German chemist who was one of the first to make an attempt to organise the elements. He attempted to organise them by looking at both physical and chemical properties. In 1817 Johann Dobreniner was able to find a remarkable pattern that he was able to use for it could not have been a coincidence. In 1829 Johann Dobreniner then came up with the Law of Triads which was that "nature contained triads of elements the middle element had properties that were an average of the other two members when ordered by the atomic weight."Alexandre Émile Beguyer de Chancourtois was a French Geologist who designed a kind of spiral that was arranged on a cylinder but was based on their properties. On the graph the elements were ordered by increasing atomic weight and the similar elements were lined up vertically. Chancourtois was one of the early ones to notice that similar elements seemed to occur at regular intervals as the elements were arranged according to their atomic weight. Even though Chancourtois had taken an important step towards the development of the periodic table he did not receive much recognition for his work.
John Newlands was an English chemist who also noticed a pattern while he was...
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