The '''mass number''' is the sum of the number of [[neutron]]s and [[proton]]s in the [[nucleus]] of an [[atom]].<ref>Wile, Jay L. ''Exploring Creation With Physical Science''. Apologia Educational Ministries, Inc. 1999, 2000.</ref> The atomic number is determined by the [[isotope|isotopic]] atomic weight.
==See also==
*[[Atomic number]]
*[[Atomic mass]]
==References==
<references/>
[[Category:Chemistry]]
[[Category:Physics]]
