![]() ![]() The impact of the Yorkshire-born family's work can be put no better than by Max Perutz, a recipient of one of those 27 Nobels: In the last century, 27 Nobel prizes have been awarded for discoveries directly resulting from the use X-ray crystallography. They could begin to unravel the structures of molecules. Credit: Jeff Dahlįrom that moment on, the mysterious way that atoms interact with each other was within the grasp of scientists. X-ray diffraction pattern of an enzyme crystal. Their work not only confirmed the existence of atoms but also showed how they come together to form compounds. The result of this diffraction is what was captured on the photographic plate by the Bragg team.Įven if you never paid attention in a chemistry lesson, you may recognise the ball-and-stick representation of chemical structures, where balls are the atoms and sticks the bonds that hold them together. X-rays that hit these obstacles interact with other X-rays that cause a phenomenon called diffraction, something all waves (light or sound) undergo whenever they hit obstacles. Each of these atoms has a dense core containing neutrons and protons, and less dense outer shells containing electrons. Today we know that inside crystals there are atoms arranged in regular patterns. Lawrence Bragg then came up with a formula, now known as Bragg's law, that could be used to extracted this information allowing him to work out how the atoms of sodium and chlorine are arranged in a salt crystal. They realised that tucked away in the layout of the dots was information about salt's molecular structure. ![]() ![]() Others had done similar things before, but the Braggs made an intuitive leap. They prepared a clean crystal of salt and shone X-rays on it, which created a beautiful geometric pattern on a photographic paper placed behind it. To achieve this feat, William Henry Bragg and his son William Lawrence Bragg used table salt (sodium chloride). ![]()
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