It became clear from his analysis in 1911 that the plum pudding model could not explain atomic structure .
In 1909 , Ernest Rutherford discovered that the bulk of the atomic mass was tightly condensed into a nucleus , which was also found to be positively charged .
It became clear from Ernest Rutherford 's analysis in 1911 that the plum pudding model could not explain atomic structure .
In 1909 , Ernest Rutherford discovered that the bulk of the atomic mass was tightly condensed into a nucleus , which was also found to be positively charged .