Development of periodic table - Coggle Diagram
Development of periodic table
In 1829, Johann Döbereiner recognised triads of elements with chemically similar properties, such as lithium, sodium and potassium, and showed that the properties of the middle element could be predicted from the properties of the other two.
The earliest attempt to classify the elements was in 1789, when Antoine Lavoisier grouped the elements based on their properties into gases, non-metals, metals and earths.
Alexandre Béguyer de Chancourtois
3D arrangement of the elements constituting an early form of the periodic classification, published in 1862.
Chancourtois was the first to use a periodic arrangement of all of the known elements, showing that similar elements appear at periodic atom weights.
4 years before Mendeleev announced his periodic table, Newlands noticed that there were similarities between elements with atomic weights that differed by seven. He called this The Law of Octaves
even when Mendeleev had published his table, and Newlands claimed to have discovered it first, the Chemical Society would not back him up. In 1884 he was asked to give a lecture of the Periodic Law by the Society. Finally, in 1998 the Royal Society of Chemistry oversaw the placing a blue commemorative plaque on the wall of his birthplace, recognizing his discovery at last.
Julius Lothar Meyer
Meyer was just four years older than Mendeleev, and produced several Periodic Tables between 1864-1870.
His first table contained just 28 elements
In 1868 he incorporated the transition metals in a much more developed table. This 1868 table listed the elements in order of atomic weight, with elements with the same valency arranged in vertical lines, strikingly similar to Mendeleev’s table.
Mendeleev discovered the periodic table while attempting to organize the elements in February of 1869.
Mendeleev’s achievement was to leave gaps for undiscovered elements. He even predicted the properties of five of these elements and their compounds. And over the next 15 years, three of these elements were discovered and Mendeleev’s predictions shown to be incredibly accurate.
He fired the newly-developed X-ray gun at samples of the elements
He used this to calculate the frequency and found that when the square root of this frequency was plotted against atomic number, the graph showed a perfect straight line. He’d found a way to actually measure atomic number.
The amount of energy that is given out depends on how strongly the electrons are attracted to the nucleus. The more protons an atom has in its nucleus, the more strongly the electrons will be attracted and the more energy will be given out.