Rutherfordium is element #104 and is a man-made element, meaning it is not found in nature. This is due to it's relatively short half-life. As a trans-uranium element (all those that come after the element Uranium) it's radioactive. The most stable isotope is Rf 267, with a half-life of just over an hour. The number 104 is the element's atomic number, which tells you the number of protons in the nucleus. Subtracting that number from the stable isotope (267-104) gives you the number of neutrons, or 163. Since the element is electrically neutral, it possesses 104 electrons to counter the 104 protons, each having negative and postive electrical charges, respectively. The estimated density is 23 g/cm^3. The color of the element has not been determined, and it's found only in the laboratory.
Terbium is element #65, is silvery-white in color, is a rare-earth metal that's found mixed in with other minerals, with a density of 8.23 g/cm^3. The most stable isotope is Tb 159, which has 159 electrons and (159-65) or 94 neutrons. See more info at the links: