Question

The atomic numbers of transition elements of the 6d series of ′d′ block elements:
A.89
B.104
C.105
D.All of the above

Answer 1

To answer this question, recall the formation of the periodic table. The modern periodic law developed by Moseley states that the physical and chemical properties of elements are the periodic function of their atomic number. The 6d series is present in the seventh period, the orbitals with lower energies than 6d will be fully filled in this case.

Complete step by step answer:
The d-block elements that have 1 to 10 electrons present in the d-orbital of the penultimate energy level and 1-2 electrons in the s orbital which is the outermost orbital. D- block elements are generally malleable and ductile, good electrical and thermal conductivity, and good tensile strength.
D-block consists of four series in which filling up of 3d, 4d, 5d or 6d orbitals is involved. 6d elements lie in the seventh period. The lower energy orbitals, i.e. 1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p, 4d, 4f, 5s, 5p, 5d and 6s will all be fully filled. The 6d elements will thus start with the atomic number = 89.
This series starts with element Ac (atomic number 89) and includes elements from Rutherfordium/Kurchatovium (atomic number 104) to Copernicium. This period is still incomplete. The elements that belong to this series are involved in the gradual filling of 6d orbitals.

Hence, the correct option is D.

Note:
There are 4 blocks in the periodic table: s-block, p-block, d-block and f-block. All of the s-block elements are metals. Usually, they are shiny, silvery, good conductors of heat and electricity, and lose their valence electrons easily. The p-block has the biggest variety of elements and is the only block that contains three types of elements: metals, nonmetals and metalloids. d-block elements have properties that are between s-block elements and p-block elements properties. It consists of transition metals. The f-block elements are mostly radioactive. The block names were created to represent the quality of the spectroscopic lines of the atomic orbitals.