Question

The period number tells us the following about the element:

O number of electron shells in the atom
O the atomic mass
O number of valence electrons
number of electrons on outer shell

Answer 1

Number of electron shells in the atom.

Step-by-step explanation:

Each period in the periodic table corresponds to a different energy level or electron shell in an atom. The period number indicates which energy level the outermost electrons of the elements in that period are located in.