Element Name Promethium Atomic Number: 61 Atomic Mass: 145 Protons: 61 Neutrons: 84 Electrons: 61 Configuration: 2-8-18-23-8-2 Element Type: Metal Family: Rare Earth Metals Period: 6 Interesting Facts about Element Name: *Isotopes of promethium are used to produce heat in nuclear-powered batteries. *Promethium isotopes are used to produce X-rays in portable X-ray machines. *Promethium is radio active. *Promethium is usually a light pale blue.