Answer:
The elements highlighted in red have in common the fact of belonging to the same period, which is period two. This makes electrons occupy up to level two.
Explanation:
In the periodic table you can distinguish horizontal divisions or rows called periods and vertical divisions or columns that are called groups.
The table is divided into periods that are listed from 1 to 7 from top to bottom. Elements that belong to the same period have different properties, but similar masses, because they have the same number of orbitals. That is, the elements of a given period are characterized by having electrons on the same outermost level, which is precisely the number that designates each period. For example, the elements of the third period have electrons up to level three. As the period number increases in the periodic table, the number of the energy level increases.
The elements highlighted in red have in common the fact of belonging to the same period, which is period two. This makes electrons occupy up to level two.
