Question

The highest possible oxidation states of Uranium and Plutonium, respectively are:
(A) 6 and 4
(B) 7 and 6
(C) 4 and 6
(D) 6 and 7

Answer 1

Hint:. Oxidation state of an element is the number of electrons lost or gained in the process of making bonds with other elements. The atomic number of Uranium is 92 and that of Plutonium is 94.

Complete step by step answer:
Oxidation state of an element is the number of electrons lost or gained in the process of making bonds with other elements. We will take a look at the electronic configuration of Uranium and Plutonium to find their maximum oxidation state.
- Uranium is a radioactive element which is placed in an actinide series of elements. Its chemical symbol is U and its atomic number is 92. We know that total electrons present in an element are equal to its atomic number.
- The electronic configuration of U is $[Rn]5{f^3}6{d^1}7{s^2}$ .
 -We know that elements lose or gain electrons in order to make bonds with other elements. Here, U will lose electrons because the orbitals are less than half filled. So, they will lose 3 electrons of 5f orbital, 1 from 6d orbital and 2 from 7s orbital. Thus, it can lose a maximum of 6 electrons to gain a noble gas configuration. Thus, the maximum oxidation state of the element Uranium is +6.

-Plutonium is also an actinide element. Its atomic number is 94. The electronic configuration of Plutonium is $[Rn]5{f^6}7{s^2}$.
- Plutonium can exist in oxidation states like +2, +3, +4, +5, +6 and +7. So, the maximum oxidation state which Plutonium can exhibit is +7.
Thus, we can conclude that the highest possible oxidation state of Uranium and plutonium is +6 and +7.
So, the correct answer is “Option D”.

Note: Remember that even though Plutonium has 6 electrons in its 5f orbitals and 2 electrons in 7s orbital, it does not exhibit +8 oxidation state. Both the elements Uranium and Plutonium are radioactive.