Chemistry Assessment Task : Robert Boyle

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Chemistry Assessment Task 1 Michelle Chen 11CH5 Question 1: 1660 – Robert Boyle defined elements and compounds, which are the basis of the periodic table. 1778 – Antoine Lavoiser distinguished the elements into 4 categories: metals, non-metals, elastic fluids (gases) and earths. This was the first classification of the elements. 1828 – Jakob Berseius arranged the first table of elements according to atomic masses, and introduced symbolising elements with elements. 1828 – Johann Dobereiner grouped elements with similar properties into triads. This was the first attempt to class elements into groups based on their properties. 1864 – John Newlands continued the work of Dobereiner. He ordered the elements according to atomic…show more content…
1913 – Henry Moseley tested whether elements should be based on the charge of the nucleus. He found that there was a pattern between adjacent elements. Moseley devised the basics of the atomic number. 1913 – Niels Boh proposed his model of the atom with protons in the nucleus and electrons in the shells around it. He also proposed that elements with the same number of electrons in the valency shell meant that they had similar properties. 1913 – Wolfgang Pauli used quantum physics to explain that the first period of the periodic table could accommodate two elements, while the second period could hold eight. 1940 – Glenn Seaborg discovered elements from number 94 – 102. Question 2: a) Johann Dobereiner had first grouped some of the elements into groups of three, or else called triads. He created these triads and ordered them according to their atomic weights. He found that by ordering Lithium, Sodium and Potassium this way, they had an ascending level of reactivity with water. Also, by grouping them this way, John Newlands found that every eight elements from one element had similar physical and chemical properties. b) Other triads that were identified during the early construction of the period included: • Sulfur, Selenium and Tellurium • Carbon, Nitrogen and Oxygen c) i) In this time of history, atomic numbers were not used because scientists had not yet found that there would be a pattern among the X-ray frequency given off by the
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