In 1917, Rutherford discovered something new, he bombarded alpha particles on nitrogen gas and noticed that occasionally an oxygen atom is produced. From this he concluded that the alpha particles removes proton from the nucleus (positively charged particle). He named this playing with marbles and he become the first one to split an atom. Thus, by bombarding nitrogen with alpha particles, he observed the production of oxygen, a different element.
Therefore, he said bombarding atoms with particles is similar to playing with marbles.
