Question

why did Rutherford choose gold and not any other lighter element (such as alluminium) for his experiment? explain your answer given two reasons.

Answer 1

Rutherford used gold foil for his experiment because gold is most malleable metal, it can be converted into thin foils, alpha particles are very heavy with less penetration power, hence thinnest sheet of gold was required..  

Answer 2

Explanation:

He actually used also Aluminium, Silver, and Copper. He did so because he wanted to prove that the Rutherford cross section was proportional to Z2.In any case, he needed to use malleable material (metals) in order to achieve a micrometer-thin foil to prevent the entire α beam to be absorbed by the target