GCSE AQA Trilogy Models of the atom - AQA Further developments to the atomic model The idea of the atom as the building block of matter has developed over time. What was thought of as a single ...

Source: Encyclopaedia Britannica In 1943, Chadwick travelled as head of the British mission to Los Alamos in the US, where scientists were developing the first atomic bomb.

Chadwick repeated their experiments but with the goal of looking for a neutral particle -- one with the same mass as a proton, but with zero charge. His experiments were successful.