Heavy and light analogues of hydrogen probe the limits of quantum chemistry
To make the ultra-light isotope, scientists swapped the proton with a positively charged muon, which has just 11% of the mass of a proton. And to make ultra-heavy hydrogen, they replaced one of the electrons in a helium atom with a negative muon.
The researchers tested the behaviour of these new atoms in a chemical reaction called a hydrogen exchange, in which a lone hydrogen atom plucks another from a two-atom hydrogen molecule — just about the simplest chemical reaction conceivable. In a paper in Science1, they report that both the weedy and the bloated hydrogen atoms behave just as quantum theory predicts they should.
