the rows of the periodic table are called
In the periodic table the elements are arranged into periods and groups. A row of elements across the table is called a period. Each period has a number: from 1 to 7. Period 1 has only 2 elements in it: hydrogen and helium.Period 2 and Period 3 both have 8 elements.Other periods are longer. row of elements across the table is called a period. Each period has a number: from 1 to 7. Period 1 has only 2 elements in it: hydrogen and helium. Period 2 and Period 3 both have 8 elements.