Question

There are two rows of inner transition elements in the periodic table each containging 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

$m_{l} = 2l + 1 = 7$

There are 7 electrons with $+ \frac{1}{2}$ spin and 7 electrons with $- \frac{1}{2}$ spin. Hence, total electrons are 14.