Question

The period number in the long form of the periodic table is equal to

• A. magnetic quantum number of any element of the period.
• B. maximum Principal quantum number of any element of the period.
• C. maximum Azimuthal quantum number of any element of the period.
• D. atomic number of any element of the period.

Answer 1

The correct option is B maximum Principal quantum number of any element of the period.

Each row of the periodic table is called a period. All elements which are present in the same period have the same maximum principal quantum number value ( or number of shells).

Same atomic orbitals mean they have the same principal quantum number $\left(n\right)$, therefore the period number of long form of the periodic table refers to the maximum principal quantum number of any element of the period

Hence, option (C) is correct.