Prepare a paper to be presented at a seminar based on the topic ‘Earlier attempts of classification of elements’

‘Earlier attempts of classification of elements’

i. In 1789, the French scientist Antoine Lavoiser classify the known elements into metals and non-metals. But by that time, he was not able to classify metalloids which show the properties of both metals and non-metals.

ii. In 1807, John Dalton discovered an Atomic Theory. He concluded that each element has a fixed mass.

iii. In 1829, the German Chemist, J.W Dobereiner was the first to consider the idea of trends among properties of elements. He showed that the atomic mass of the middle element was approx. equal to the mean of atomic masses of other two elements.

iv. In 1862, ChanCourtoise put forward the idea of “Telluric helix” to classify elements. He arranged the atoms in spirally ascending order of their atomic masses in a cylindrical way. He noticed that elements of similar properties will line up vertically.

v. In 1863, John Alexander Newlands proposed the law of octaves. Law of octaves states that “every eighth element has properties similar to the firsts element”

vi. In 1868, The German scientist Julius Lothar Meyer plotted a graph of atomic volume against the atomic mass of theelements. He concluded that atomic mass is the fundamental property of elements.