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

Hint: To solve this question, you need a good knowledge about the periodic table and the periodic properties. Also, you need to know about the lanthanides and actinides. The inner transition elements are the elements of f-block in the periodic table.

Complete step by step answer:
We know that the lanthanides and actinides are the inner transition elements and they are placed in the f-block in the periodic table. Since the last electron in inner transition elements goes to the f-subshell, so it is placed under f-block in the periodic table. The general electronic configuration of inner transition element is $4{{f}^{1-14}}5{{p}^{6}}5{{d}^{0-1}}6{{s}^{2}}$. From this general electronic configuration, it is clear that the f-subshell only contains fourteen electrons. So, each row of this inner transition series only contains 14 elements.
Since f-orbital has seven values for magnetic quantum number, each row of inner transition elements contains 14 elements.

Note: The important points about the inner transition elements include, they form coloured ions, they show variable oxidation states and also actinides are radioactive elements. The inner transition elements from the atomic number 92 to 103 are synthetic and radioactive.