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.
Given the discoveries of electrons in 1897 by Thomson, Rutherford and other scientists decided that a positively charged particle must exist to center the electron to create equally neutral atoms. Thompson proposed the name âpositive raysâ.iven the discoveries of electrons in 1897 by Thomson, Rutherford and other scientists decided that a positively charged particle must exist to center the electron to create equally neutral atoms. Thompson proposed the name âpositive raysâ.