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.
He did an expirement that involved shooting a beam of particles at a thin sheet of gold. Through this he discovered that there is a small, dense, positively charged nucleus; most of an atomâs mass in the atomâs nucleus; atoms contain mostly empty space; electrons move in empty space in the atom.