What is the mendleev periodic table advantage and disadvantage
Answers
Answer:
advantages : 1. atomic masses of some elements were revised ; so as to give them proper place in the periodic table in accordance with their properties.
2. mendeleev kept vacant places in the periodic table for elements not discovered till them . he also predicted properties of these elements even before they were discovered later and were found to be correct.
3. there was no place reserved for Noble gases in mendeleev original period table . when Noble gases were discovered later , he created the zero group without disturbing the original periodic table in which the Noble gases were fitted very well.
disadvantage: 1. the whole number atomic mass of the elements Cobalt and nickel is the same . therefore there was an ambiguity regarding their sequence in the mendeleev's periodic table.
2. isotopes were discovered long time after mendeleev put forth the periodic table. as isotopes have the same chemical properties but different atomic masses , a challenge was posed in placing them in the mendeleev's periodic table.
3.when elements are arranged in an increasing order of atomic masses, the rise in atomic mass does not appear to be uniform . it was not possible, therefore, to predict how many elements could be discovered between two heavy elements.
4. hydrogen resemble alkali metals as well as halogens. therefore, no fixed position could be given to hydrogen in periodic table.