Beryllium has an atomic number of 4 how many neutrons does the isotope beryllium-9 have
The isotope beryllium-9 has 5 neutrons.
To determine this, you subtract the atomic number (which represents the number of protons) from the mass number. In this case, the mass number is 9, so subtracting the atomic number (4) from 9 gives you the number of neutrons (5).
To calculate the number of neutrons in an isotope, you need to subtract the atomic number from the mass number.
In this case, the isotope is beryllium-9, meaning it has a mass number of 9 and an atomic number of 4.
Number of neutrons = Mass number - Atomic number
Number of neutrons = 9 - 4
Number of neutrons = 5
Therefore, the isotope beryllium-9 has 5 neutrons.