http://www.sciencedaily.com/releases/2007/03/070323171548.htm
I Found a sort of yardstick I've been needing.... gold electrons whip around atom at roughly .5C [snip] In an atom, where electrons race around the nucleus like buzzing bees, the velocity of an electron doesn't get anywhere near the speed of light until the atomic nucleus fills up with lots of positively charged protons - the negatively charged electrons have to move faster to keep from being pulled into the highly positive nucleus. This occurs in the transition metals of the periodic table of elements, metals ranging from tantalum and tungsten to platinum and gold. In a gold atom, with 79 protons in the nucleus, the 79 electrons whip around the nucleus at about half the speed of light.[/snip]
