Pre-Read Isotopes

Isotopes and Radioactivity

Match

Match the subatomic particles to their charges.

• Protons

• Neutrons

• Electrons

Positive

Neutral

Negative

• Positive

• Neutral

• Negative

What is an isotope?

An isotope is one of two or more types of atoms of a chemical element with the same number of protons but with different numbers of neutrons and therefore different atomic masses.

Every chemical element has one or more isotopes. The isotopes of an element occupy the same position in the periodic table. They behave similarly in chemical reactions but may have different physical properties.

How to talk about isotopes

Isotopes generally are referenced by their mass number, which is the total number of protons and neutrons in the nucleus.

For example, the most common form of hydrogen has a mass number of 1 and we call it Hydrogen-1 - it has no neutrons. Hydrogen-2 on the other hand has a proton and a neutron so its mass number is 2. The same goes for Hydrogen-3 which has 2 neutrons.

Multiple Choice

What subatomic particle determines which type of element an atom is?

• Proton

• Neutron

• Electron

What is a nuclear reaction?

So far, when you have been looking at atomic structure and chemical reactions you have been focusing on what happens outside of the nucleus.

Nuclear reactions are those that occur in the nucleus of an atom.

What is a nuclear reaction?

When we look at nuclear reactions, we look at what happens inside the nucleus of an atom. Atoms can gain or lose energy, protons and neutrons.

This means that these kinds of reactions can alter the chemical identity of an element!

What is radioactivity?

When atoms of an element have extra neutrons or protons it creates extra energy. When the nucleus of an atom spontaneously breaks apart, it emits energy. This is radioactivity.

Not all elements do this. The main aim is to become stable so those that are already stable are just chilling. We can make it happen in a nuclear reactor or particle accelerator though.

Multiple Choice

What is the name of the glue that holds protons and neutrons together in the nucleus?

• Nuclear Force

• Radiation

• Subatomic Fission

• Chemical Bonds