The element radium has a mass number of 226 and an atomic number of 88. how many neutrons does an atom of radium have?
A. 88
B. 138
C. 314
D. 226
The number of neutrons in an atom can be calculated by subtracting the atomic number from the mass number.
Neutrons = Mass number - Atomic number
Neutrons = 226 - 88
Neutrons = 138
Therefore, an atom of radium has 138 neutrons.
B. 138