Well, I said I’d start doing sciencey posts, so this is my first one.
I won’t go into too much detail, but enough to make it interesting. Hopefully.
So, in the world we live in now, it’s common knowledge that an atom consisted of a minuscule nucleus, made up of protons and neutrons, surrounded by a shell-like structure, which is electrons whizzing around REALLY fast.
I guess it looks kinda like this:
But before Ernest Rutherford came on the scene, the accepted model of the atom was known as the ‘plum pudding model’, which I image to look like:
But this picture probably gives you a better idea of what they meant:
So anyway, in 1906, Rutherford was carrying out an experiment involving shooting alpha particles though a mica sheet (thrilling stuff). Whilst doing this, he noticed most of the particles passed straight through the sheet, suggesting that the atoms were mostly empty space. By 1909 he had developed the nuclear model of the atom.
In 1911, Rutherford was carrying out further experiments with his pals Hans Geiger (of Geiger-counter fame) and Ernest Marsden. This time using gold foil (of about 100 atoms thick) instead of mica.
Again, they fired alpha particles at the sheet. Most of the alpha particles went straight though, but about 1 in 20000 ‘bounced back’. Of course, this didn’t just happened by chance. The experiment was repeated SO MANY time to the most pedantic of extremes and it still occured. Rutherford described this as quite the most incredible event that has ever happened to me in my life. It was almost as if you fired a 15 inch shell at a piece of tissue paper and it came back and hit you’.
Think about it, Rutherford is here thinking the atoms were empty space, and suddenly he’s getting alpha particles being shot back at him.
But this makes sense, obviously atoms have mass, otherwise nothing would exist. So the fact that the alpha particles bounce back shows that most of the mass and all of the positive charge is concentrated at the centre- what we know as a nucleus.
So that was pretty much the beginning of nuclear physics. Not bad.
