the element radium has a mass number of 226 and an atomic number of 88. how many neutrons does an atom of radium have?
88
314
138
226
To find the number of neutrons in an atom of radium, subtract the atomic number (number of protons) from the mass number.
Number of neutrons = mass number - atomic number
Number of neutrons = 226 - 88
Number of neutrons = 138
Therefore, an atom of radium has 138 neutrons.