Question: why is the atomic number for beryllium 4?
Answer: Element Facts for Atomic Number 4. The element with atomic number 4 is beryllium, which means each atom of beryllium has 4 protons. A stable atom would have 4 neutrons and 4 electrons. Varying the number of neutrons changes the isotope of beryllium, while varying the number of electrons can make beryllium ions.