Question

There are two rows of inner transition elements in the periodic table each containing $14$ elements. The reason for this may be

• A. f-orbital has seven values for magnetic quantum number, hence total electrons are 14
• B. in the periodic table there is space to accommodate 14 electrons only
• C. only 28 inner transition elements have been discovered till date
• D. 28 is the maximum number of elements that any block can accommodate.

Answer 1

Answer: (A)

f-orbital has seven values for magnetic quantum number, hence total electrons are 14

Answer 2

For f-orbital, $l = 3$, $= 2l + 1 = 7$ There are $7$ electrons with $+1/2$ spin and $7$ electrons with $-1/2$ spin. Hence, total electrons are $14$.