The Nucleus Atoms are electrically neutral The number of protons in a nucleus is equal to and determines the number of orbiting electrons the chemistry the element name Hydrogen ( 1 1 H) 1 proton, 0 neutrons Mass = 1 Helium ( 4 2 He) (Alpha-particle) 2 protons, 2 neutrons Mass = 4 Uranium ( 238 92 U) 92 protons, 146 neutrons Mass = 238
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