Answer:
The common about the elements of a period is that they have the same number of atomic orbitals.
Step-by-step explanation:
The period of an element corresponds to the principal quantum number of the valence shell.
They are a total of 7 periods in the periodic table.
The periods represent the energetic levels that an atom has.
The periods are ordered in 7 horizontal rows.
For example, in the first period we have the Hydrogen (H) and the Helium (He).