Question

What are D-block elements? Compare the element of first transition series with regards to.

Answer 1

Answer:

The d-block elements vary from the p-block elements with respect to the location where the last electron enters the atoms of these blocks. This causes variations in the oxidation states of elements of both the blocks

-The periodic table is divided in 4 different blocks namely s-block, p-block, d-block and f-block. They show different variations with respect to the change in the oxidation states of the atoms as the electrons present in the valence shell are different in different blocks.

-The different blocks are classified on the basis of the location of the last valence electron entering the shell of the atom. In s-block elements, the valence electrons enter the s-subshell and in p-block, the valence electrons enter the p-subshell. In d-block, the valence electron enters the d-subshell due to the Aufbau’s principle.

-The configuration of p-block elements can be shown as ns2np1−6ns2np1−6 while that of d-block can be shown as (n−1)d1−10ns0,1,2(n−1)d1−10ns0,1,2 . This is the main reason for the difference in the oxidation states of both the p-block and d-block elements.

-The oxidation state of d-block elements varies by 1 unit only while that of p-block elements varies by 2 units. This is because the electrons are excited from the s-subshell in p-block elements creating the number of unpaired electrons as 2. In d-block elements, electrons are lost and excited from the d-subshell and not from s-subshell in their second oxidation states.

-If we take the example of Mn and S, we see that S has 6 electrons in the valence shell and its different covalencies can be formed as

- Mn atoms form a cation with charge +2 if 2 electrons are removed from it. The outermost shell is 4s. So, when 2 electrons are removed, the configuration will become 1s22s22p63s23p63d51s22s22p63s23p63d5. The other electron is now removed from the d-subshell itself and so the change in the oxidation state is 1 only and not 2 unlike S.

Thus we see the difference between the transition elements and p-block elements with reference to variability of oxidation states.