Isotopes

Question 1

What is the mass number of an atom?

Answer 1

The total number of protons and neutrons in the nucleus.

Question 2

What is the atomic number of an atom?

Answer 2

The number of protons in the nucleus.

Question 3

What is an isotope?

Answer 3

Isotopes are atoms of an element with the same number of protons but a different number of neutrons. You can recognise isotopes of the same element because they will have the same atomic number but different mass numbers. Isotopes of an element have the same chemical properties because they have the same number of electrons.