The Development of the Periodic Table of the Elements
The periodic table is defined as the most common arrangement of the periodic system. This is the classification of chemical elements into periods (corresponding to the filling of successive electron shells) and groups (corresponding to the number of valence electrons) and describes the modern version that is used today. However, this was not always how it was structured and described – like the atom, the Periodic Table has been developed over time due to the contributions of a number of scientists (and is still developing even today).
Long before the development of the modern Periodic Table, ancient philosophers such as Aristotle believed the world to be made up of four distinct elements: earth, water, air and fire. Although this is not true, they were thinking along the right lines as these are examples of the states of matter solids, liquids, gases and plasma.
The first significant contribution towards the modern Periodic Table was made by the French chemist Lavoisier in 1789, who with his wife compiled the first modern chemical textbook named Traite Elementaire de Chimie (Elementary Treatise of Chemistry), which included a list of the known elements at the time. An advantage of Lavoisier’s work is that he distinguished between metals and non-metals but a disadvantage was that he included some compounds and mixtures as elements and substances that were neither, for example light and heat (which he called “caloric”). Nevertheless, this was recognised by the scientific community as a step forward in chemistry – he earned himself the nickname “the father of modern chemistry”. Ultimately, his work marked the beginning of categorising the elements, which would prove incredibly useful later on.
The next significant step was made by Jons Jakob Berzelius, a Swedish chemist. He was interested in all sorts of compounds and this culminated in the discovery of new elements, cerium and thorium. As he was constantly working with many elements of compounds, it inspired him to come up with a system of referring to them with ease, and therefore created a naming system for them with letter symbols instead of picture signs. Also, in 1828, he published a table of atomic weights, which would serve useful for other chemists to build on his work and discover patterns that the elements showed.
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Quality of writing
This essay is very well written, it is easy to follow and the information is provided in a clear and coherent manor. In addition to this there are no obvious issues with spelling punctuation or grammar.
Level of analysis
The candidate gives a clear and detailed account of the way in which the periodic table was developed. The candidate has clearly taken the time to research this topic extensively which is shown by the addition of a bibliography starting the resources that the candidate has used. Furthermore the candidate has taken the time to right up a account in their own words, which is evident by the language used, this demonstrates a good understanding of this topic. Finally, the candidate ends this essay with an appropriate conclusion, they state that the future will see further developments and they add a personal touch, you should always try to give a personal reaction. However, the conclusion could be improved by summarising the key facts, perhaps by listing the scientists involved in developing the periodic table with a brief sentence on each, this allows you to tie up loose ends and bring everything together, which helps draw the essay to a close.
Response to question
This essay starts well, the introduction describes the periodic table and the candidate states the way in which the elements are classified. However it could be improved by the candidate making it clear that they planed to discuss how the periodic table was developed, a good introduction should state the topics you plan to cover, this sets the premise of the essay. That said, the candidates overall response is very good, they give a detailed account of the way in which various scientist contributed the the development of the periodic table.