Write a complete symbol, including atomic mass and mass number, for an element with 50 protons and 70 neutrons.

Answer 1

Everything that @Stephanie B said is correct. But if you are looking for the conventional way to write this, you put the atonic number (protons) on the bottom, and the atomic mass (protons + neutrons) on the top.

¹²⁰Sn

₅₀

Answer 2

The number of protons determines what the element is: that is the atomic number. Which element has atomic number = 50?

If you forgot the difference between atomic number and mass number, remember that protons and neutrons are almost all of the mass in an atom. So, the mass number is the sum of neutrons and protons, whereas the atomic number is only the number of protons. So, the mass number is always the larger number.