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
Up An' Atom Base, Texas, and was re-configured as a TB-29 trainer in April 1950 by the Oklahoma City Air Materiel Area at Tinker Air Force Base. Its subsequent assignments were to: "Up An' Atom" was dropped from the Air Force inventory in November 1956. It was transferred to the U.S. Navy and used as a target at the Naval Ordnance Test Station at China Lake, California. Up An' Atom Up An' Atom was the name of a B-29 Superfortress (B-29-36-MO 44-27304, Victor number 88) configured during World War II in the Silverplate project to carry an atomic bomb. Assigned to the 393d