Topic 1 Key Concepts in Chemistry - Isotopes and Relative Atomic Mass

Question 1

What is an isotope?

Answer 1

Isotopes are atoms with the same number of protons (so they are the same element) but a different number of neutrons.

Isotopes of an element have the same atomic number but different mass numbers.

Question 2

Boron has the atomic number 5 and the mass number 11. How many protons, electrons and neutrons does Boron have?

Answer 2

5 protons
5 electrons
6 neutrons

Question 3

Why is the relative atomic mass not always a whole number?

Answer 3

Different isotopes of the same element have different mass numbers. The relative atomic mass is an average of the masses of all these isotopes.

Question 4

What two values would be required to calculate the relative atomic mass of chlorine?

Answer 4

Mass numbers and relative abundances of all the isotopes of chlorine.