what are the ACHIEVEMENTS OF MENDELEEV PERIODIC TABLE
Answers
element with a slightly greater atomic mass were placed
before an element with a slightly lower atomic mass with an inverted sequence so as to group the elements with similar properties. For example, cobalt with atomic mass 58.9 was placed before nickel with atomic mass 58.7.He left some gaps in the Periodic Table with the prediction of
existence of some elements that were not discovered at that time.He named the future elements by prefixing a Sanskrit numeral, Eka (one) to the name of preceding element in the same group.For instance, scandium, gallium and germanium, discovered later, have properties
similar to Eka–boron, Eka–aluminium and Eka–silicon, respectively.Noble gases like helium (He), neon (Ne) and argon (Ar) were discovered
later as they are present in exceptionally low concentrations in the atmosphere due to their inertness.
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Systematic Study of elements.
Mendelèev was the first scientist to arrange all the then-known elements into groups and periods, which helped in identifying the physical and chemical properties of elements.
Prediction of Unknown elements.
Mendelèev left some spaces in his periodic table. Instead of looking at these spaces as defects, he predicted the existence of some elements that were not discovered at the time. He had predicted their chemical properties based on elements present in the same group as well. Later on, his predictions were found to be correct.
Example: He predicted the existence of elements such as Scandium, Gallium and Germanium and named them Eka-boron, Eka-Aluminium and Eka-Silicon respectively.
Placement of Noble gases.
Mendelèev's Periodic Table could accommodate noble gases when they were discovered. Noble gases such as Argon, Helium and more weren't discovered when Mendeleev formulated his periodic table. On their discovery, they could be placed in a new group called the 'Zero Group' without disturbing the pre-existing order.