(i) Which orbitals are filled with electrons in 3rd period?(ii) Which of the lanthanoids is man-made element?(iii) To which series do man-made elements belong?
(i) In third period, 3s and 3p orbitals are filled.(ii) Promethium (Pm) with atomic number 61 is a man-made lanthanoid.(iii) Actinoid series (f-block elements).