A second Q and A video to mark our 500th video - the first one is at: http://youtu.be/op1Dp1r66OE More chemistry at http://www.periodicvideos.com/ Follow us on Facebook at http://www.facebook.com/periodicvideos And on Twitter at http://twitter.com/periodicvideos From the School of Chemistry at The University of Nottingham: http://www.nottingham.ac.uk/chemistry/index.aspx Periodic Videos films are by video journalist Brady Haran: http://www.bradyharan.com/ A run-down of Brady's channels: http://bit.ly/bradychannels