Here it is - five grams of caesium in water... But did you know caesium (aka cesium) is also used to define the length of a second? More links in description below ↓↓↓ For extra footage and replays of the reaction visit http://www.youtube.com/watch?v=pWXQ2tYzJaU Support Periodic Videos on Patreon: https://www.patreon.com/periodicvideos A video on every element: http://bit.ly/118elements More 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://bit.ly/NottChem Periodic Videos films are by video journalist Brady Haran: http://www.bradyharanblog.com Join Brady's mailing list for updates and extra stuff --- http://eepurl.com/YdjL9