Question

Elements are placed into the same period on the periodic table of the elements because they ___________.

Answer 1

Answer:

have the same number of electron energy levels

Explanation:

All of the elements in the same period have the same number of atomic orbitals that are occupied by electrons that are in constant motion. For example the elements in the first period have one orbital for its electrons. The elements in the second period have two orbitals for their electrons. As you move down the table, every row adds an orbital. At this time, there is a maximum of seven electron orbitals.