Question

How many protons, neutrons, and electrons are in an atom of beryllium with a mass number of 9? protons, electrons, neutrons protons, electrons, neutrons protons, electrons, neutrons protons, electrons, neutrons

Answer 1

1) Beryllium. This element is in the second group and the second period. The atomic number is 4 which is the number of protons.

The mass number is the sum of neutrons and protons.

Assuming the element has no charge the number of electrons is equal to the number of protons.

Protons: 4.

Neutrons: the mass number - the atomic number = 9 - 4 = 5.

Electrons: 4.