Question

In group 6 of modern periodic table Mo (VI) and W (VI) are found to be more stable than Cr (VI)

Answer 1

In the case of d-block elements if the heavier elements are containing the higher oxidation then they are more stable than the same elements with lower oxidation states. Stability of the elements is going to depend on the oxidation of the element also.

Complete answer:
- In the question it is given that to find the reason behind the more stability of the elements Mo (VI) and W (VI) when compared to Cr (VI).
- The given elements are molybdenum (Mo), tungsten (W) and chromium (Cr).
- All the three elements belong to the same block (d-block) and same group (6) in the periodic table.
- But the elements Mo (VI) and W (VI) are more stable than the Cr (VI).
- The reason behind this concept is as we are moving from top to bottom in the periodic table the stability of the elements with higher oxidation state is going to increase.
- The elements molybdenum and tungsten are present below the chromium in the group 6 of the periodic table.
- Therefore the elements Mo (VI) and W (VI) are more stable than the chromium (VI).

Note:
The roman number which is in brackets after the chemical element represents the oxidation state of the particular element. One element can show many number of oxidation states, the oxidation of the element is going to depend on the number of electrons are going to accept and donate.