Model of an atom

• How does the size of the nucleus compare to the whole atom?

  The nucleus is about 10,000 times smaller than the whole atom.
• Who discovered the nucleus?

  Ernest Rutherford through the gold foil experiment.
• What was the plum pudding model?

  J.J. Thomson’s model of the atom, where electrons were thought to be embedded in a positive ”dough“
• How did Rutherford’s gold foil experiment disprove the plum pudding model?

  Most alpha particles passed through, but some were deflected, showing that atoms have a small, dense, positively charged nucleus.
• What did Niels Bohr propose about electron arrangement?

  Electrons orbit the nucleus in fixed energy levels (shells).