Question

give the number of elements in 2nd and 5th period in modern period in modern periodic table?

Answer 1

A period 5 element is one of the chemical elements in the fifth row of the periodic table of the elements.THE periodic table is laid out in rows to illustrate recurring trends in the chemical behaviour elements as their atomic number increases :a new row is begun when chemical behaviour begins to repeat meaning that elements with similar behaviour fall into the same vertical columns .THE fifth period contains 18 elements beginning with rubidium and ends with xenon.