# Discuss the isotopic masses of the beryllium atom. What is the most common isotope?

Well for beryllium, $Z = 4$.....
And thus there are 4 nuclear protons; and if there are 4 positive nuclear charges there must be 4 negative electronic charges, supplied by 4 electrons. Now the common isotope is ""^9Be, which means that commonly, the element contains 5 massive, NEUTRAL particles, 5 neutrons. The atomic mass of the nuclide is, as always, THE SUM of the $\text{the sum of the noocoolar particles}$ to a good first approximation.