Isotopes & Radioisotopes - Term 4 2025

What is an isotope?

An atom of the same element with a different number of neutrons

Give an example of isotopes of carbon.

Carbon-12, Carbon-13, and Carbon-14

What is a radioisotope?

An unstable isotope that emits radiation to become stable

What makes a radioisotope radioactive?

An unstable nucleus that releases radiation

What are the three types of radiation?

Alpha (α), Beta (β), and Gamma (γ)

What is alpha radiation made of?

Two protons and two neutrons

What is beta radiation made of?

A high-energy electron

What is gamma radiation?

An electromagnetic wave

Which type of radiation is least penetrating?

Alpha radiation — stopped by paper or skin

Which type of radiation is most penetrating?

Gamma radiation — stopped only by thick lead or concrete

Which type of radiation is most dangerous?

Gamma radiation — due to deep penetration and high energy

What material can stop beta radiation?

Aluminium

Name one use of alpha radiation.

Smoke detectors

Name one use of beta radiation.

Medical tracers

Name one use of gamma radiation.

Cancer treatment or sterilisation

What does ionising radiation do to cells?

Damages cells and DNA, can cause mutations and cancer

What safety measures help reduce radiation risks?

Shielding, keeping distance, and limiting exposure time

What is the difference between atomic number and mass number?

Atomic number is the number of protons; mass number is the total of protons and neutrons

Why are electrons not included in the mass number?

Because their mass is negligible compared to protons and neutrons

What does it mean if an atom is neutral?

It has equal numbers of protons and electrons

A neutral atom has 17 protons and 18 neutrons. What is its atomic number and mass number?

Atomic number = 17; Mass number = 35

Why might a radioisotope be used to sterilise medical equipment?

Gamma radiation kills bacteria and penetrates packaging without damaging the equipment

A smoke detector contains alpha-emitting americium. Why is alpha radiation suitable for this use?

Alpha particles ionise air to allow current flow, and they’re easily blocked by smoke particles

Why is shielding important when working with gamma-emitting sources?

Gamma rays penetrate deeply and can damage internal tissues, so thick shielding reduces exposure

What precautions should be taken when disposing of radioactive waste?

Use sealed containers, label clearly, store in secure facilities, and follow legal safety protocols