Natural History Museum, London, 4th April 2014
Atoms consist of a dense heart of protons and neutrons, and a chorus of electrons dancing around them. The chorus is both deeply bonded and fickle; sometimes an electron will stay faithful; jealous, even - they don't like to share orbits. Other times, when they're feeling a bit more organic, they will freely swing with the party and anything goes. (Benzene is the ultimate ring of roses.)
In doing so, those electrons, sometime passionate, sometimes prudish, define the chemistry of the physical world.
The most radical are those with only one electron in their outer energy level (coloured red in the graphic). Passionate singles, dying for a lover. They'll bond with anything. Hydrogen, lithium, sodium, potassium - the usual suspects. But add a bit more gravitas, and those single electrons start to be useful. Rubidium and Caesium's outer electron vibrations the ultimate balance spring, as seen in the No.10.
Along the table a bit to Niobium. A vital magnetic component in every rotor in every stepper motor in every timepiece we make. Tantalum - the fabric of the flux capacitor. (Both coloured purple.)
A bit further along, the staples. Iron, Cobalt, Nickel, Copper. The Meccano of timekeeping. (Green.)
Down a bit. The precious metals: Ruthenium, Rhodium, Palladium, Silver, Platinum and Gold, that make our timepieces beautiful and treasured. (Blue.)
And finally, the semiconductors and their sirens (Yellow.) They are the comme-ci, comme-ca of the chemical world. Silicon and germanium are bedrocks, but put them in with a bad crowd like boron, phosphorous and arsenic and their electron world goes nonlinear. Enough to let transistors transist. Lasers to lase. Radios to radiate. What sets Hoptroff watches apart.