Question

in Rutherford experiment how was it shown that an atom has a lot of empty space within it?why nucleus of an atom is positively charged

Answer 1

as the particles penetrated in most cases it was evident that atom had space within it....in the nucleus protons (+charges particles) and neutrons (neutrally charged particles) are there so + charge dominates over neutral and hence nucleus is positively charged

Answer 2

Rutherford observed that:
1). Most of the Alpha particles (nearly 99percent) passed the gold foil undeflected .

2). Some of Alpha particles were defected by small angle.

3). A very few Alpha particles ( 1 in 20,000 ) were either defected by a very large angle or were actually reflected back.

Rutherford derived following conclusion from the observation of his experiment.
1) Since, few Alpha particles when undeflected, there must be large empty space within the atom.

2) Since, fee Alpha particles were deflected , there must be some positively charged bodyat the center of the atom.