The element radium has a mass number of 226 and an atomic number of 88. How many neutrons does an atom of radium have?
314
226
138
88
1 answer
To find the number of neutrons, subtract the atomic number (number of protons) from the mass number. In this case, 226 - 88 = 138 neutrons. Therefore, an atom of radium has 138 neutrons.