Question

) The atomic number of magnesium is 12.

Magnesium exists as three isotopes; Magnesium-24, Magnesium-25 and Magnesium 26.
Describe, by reference to the numbers of subatomic particles, the differences between one atom of
each of these isotopes.
(2)

Answer 1

Answer: The difference between these 3 isotopes is the number of neutrons.

The atomic mass of an atom is the number of protons plus neutrons. We know that the atomic number of magnesium is 12, so therefore there are 12 protons.

In Magnesium-24, there are 24-12 neutrons = 12 neutrons.

In Magneusium-25, there are 25-12 neutrons = 13 neutrons

In Magnesium-26, there are 26-12 neutrons = 14 neutrons