This man was the first to formulate the concept of a "half-life" and also coined the terms "alpha", "beta", and "gamma" rays to describe the types of radiation given off by thorium and radium. He also confirmed Prout's hypothesis after successfully knocking a hydrogen nucleus out of a nitrogen atom, but he may be better known for an experiment with Geiger and Marsden involving a (*) zinc sulfide sheet which lit up when alpha particles were deflected onto it. That experiment lead him to conclude that the atom was mostly 
This man was the first to formulate the concept of a "half-life" and also coined the terms "alpha", "beta", and "gamma" rays to describe the types of radiation given off by thorium and radium. He also confirmed Prout's hypothesis after successfully knocking a hydrogen nucleus out of a nitrogen atom, but he may be better known for an experiment with Geiger and Marsden involving a (*) zinc sulfide sheet which lit up when alpha particles were deflected onto it. That experiment lead him to conclude that the atom was mostly empty space with a dense nucleus, replacing J. J. Thompson's plum pudding model. For ten points, name this British chemist famous for carrying out the gold-foil experiment.
This man was the first to formulate the concept of a "half-life" and also coined the terms "alpha", "beta", and "gamma" rays to describe the types of radiation given off by thorium and radium.
Ernest {Rutherford}