How do you weigh an atom? To be honest, that's a question with plenty of problems which need answering, but one thing's certain: you need some accurate scales. Now, scientists have made a set that can measure the smallest unit of mass, the yoctogram -- which is less than the mass of a single proton.
To put some numbers to that, a yoctogram is just one septillionth of a gram. So how the hell do you make scales that are that accurate?
In research reported in Nature Nanotechnology, scientists from the Catalan Institute of Nanotechnology in Barcelona, Spain, explain that they use nanotubes, which vibrate at different frequencies depending on the mass of particles or molecules resting on them.
To work properly, the scales have to be used at low temperatures. In a vacuum. The result is that the team of researchers are able to weigh atoms -- they've demonstrated it using xenon -- to the nearest yoctogram. With a single proton weighing in at 1.7 yoctograms, that means that they should be able to discern between atoms of different elements, just by weighing them. If that makes your head hurt, you're not alone. [Nature Nanotechnology via New Scientist]