EVERYDAY SCIENCE

Detailed explanation-1: -Even after 1870, Meyer and Mendeleev were still unaware of each other’s work, although Meyer later admitted that Mendeleev had published his version first. Meyer did contribute to the development of the periodic table in another way though.

Detailed explanation-2: -He corrected the known atomic masses of some elements and he used the patterns in his table to predict the properties of the elements he thought must exist but had yet to be discovered. He left blank spaces in his chart as placeholders to represent those unknown elements.

Detailed explanation-3: -Mendeleev ostensibly organized his table by increasing atomic weight, but he gave chemical properties a deciding vote. For example, tellurium is slightly heavier than iodine, but Mendeleev put tellurium first because it has the same valence as oxygen, sulfur, and other elements in its group.

Detailed explanation-4: -Therefore, the main difference between Mendeleev’s and Moseley’s arrangements of elements in the periodic table is that Mendeleev arranged elements ascendingly according to atomic masses, while Moseley arranged them ascendingly according to atomic numbers.

Detailed explanation-5: -Mendeleev was not the first person to try to organize the elements. Other scientists had listed the elements. Some of these scientists had even grouped elements with similar properties together.