rutherford fired bullets at tissue paper and one bounced back, killing the plum pudding for good.
means a 1909 physics experiment that fired alpha particles at thin gold foil and found atoms are mostly empty space with a tiny dense nucleus.
from ernest rutherford's team at manchester, hans geiger and ernest marsden doing the actual firing, expected the particles to sail through gold foil like it was fog, assuming thomson's plum pudding model of a diffuse positive charge with electrons scattered in it. instead a few particles bounced almost straight back, which rutherford said was like firing a shell at tissue paper and having it come back to hit you.
geiger marsden 1909 — the original run at manchester using radium as the alpha source
rutherford 1911 paper — introduced the nuclear atom model in philosophical magazine
bohr model 1913 — built directly on rutherford's nucleus to explain electron orbits