Period 5 element
A period 5 element is an element in the fifth period (row) of the periodic table. It contains 18 elements, beginning at Rubidium and ending at Xenon.
Period 5 elements have electrons in the first five electron shells. All period 5 elements have one or more electrons in the fifth electron shell (valence electrons). When atomic number increases by one, another electron is added. Two electrons join the 5s orbital, ten electrons join the 4d orbital, and six electrons join the 5p orbitals.