What do they look like? Tree swallows are small birds (about 14 cm long) with long wings and small legs and feet. They are irridescent greenish-blue on their head, shoulders and back, and white their chin, breast and belly. Tree swallows have a short black beak and dark brownish feet.
Ernest Rutherford concluded that an atom contains a very small, dense center, called a nucleus, with a positive charge as a result of his gold foil experiment.
Most of an atom's mass is in the nucleus. Rutherford: He conducted the gold foil experiment. Rutherford: There is a small, dense, positively charged nucleus. Rutherford: His model had electrons surrounding the nucleus at a distance. Rutherford: Atoms contain mostly empty space. Rutherford: Electrons travel in certain paths, or energy levels. Bohr