Question

define period in periodic table

Answer 1

A period is one of the horizontal rows in the periodic table, all of whose elements have the same number of electron shells. ... As atomic number increases, shells fill with electrons in approximately the order shown at right. The filling of each shell corresponds to a row in the table.

Answer 2

A period is one of the horizontal rows in the periodic table, all of whose elements have the same number of electron shells. ... As atomic number increases, shells fill with electrons in approximately the order shown at right. The filling of each shell corresponds to a row in the table.