Question

In the modern periodic table, the period number indicates the ______.

Options

• atomic number

• atomic mass

• principal quantum number

• azimuthal quantum number

Answer 1

In the modern periodic table, the period number indicates the principal quantum number.

Explanation:

In the modern periodic table, each horizontal row represents a period. The period number directly corresponds to the highest principal quantum number (n) of the outermost (valence) shell containing electrons for the elements in that specific row. For instance, elements in Period 3 have valence shell electrons occupying the (n = 3) energy level