What is the mass mumber of an element?ps:Please answered in

What is the mass mumber of an element?ps:Please answered in What is the atomic number of an element?ps:Please answered i how to coculate the atomic mass of an element 英语翻译the V-belt is an important element in the field of power what is the mass number of an atom that has 28 neutrons?请在5月 There is an element of chance in everything是什么意思? There is an element of defeating the organization 译 【选择题】The mass media keep us well（ ）of what is happening in t Perhaps there is an element of truth The atomic number of an element X is 15.The number of electr what are some uses of the element Perhaps there is an element of truth in both these pictures.