Atom to the positively charged nucleus by the attraction created from opposite electric charges. If an atom has more or fewer electrons than its atomic number, then it becomes respectively negatively or positively charged as a whole; a charged atom is called an ion. Electrons have been known since the late 19th century, mostly thanks to J.J. Thomson; see history of subatomic physics for details. Protons have a positive charge and a mass 1,836 times that of the electron, at . The number of protons in an atom is called its atomic number. Ernest Rutherford (1919) observed that nitrogen under alpha-particle
Olaf—An Atom Olaf—An Atom Olaf—An Atom is a 1913 American film directed by Anthony O'Sullivan and featuring Harry Carey. Broken by grief after his mother's death, Olaf becomes a wanderer. He is treated cruelly until he is given a meal by a woman at the homestead where she lives with her husband and baby. Olaf is able to return her kindness when he overhears a plot to rob the settlers of their home. He alerts the couple and delays the would-be thieves long enough for the husband to file a claim on his land. Olaf is injured by the claim jumpers but