Year 10 Science · Unit 2 · Lesson 23

Radioactive Decay, Alpha and Beta Reactions

Foundation Worksheet

Name

Date

Class

Learning Goals

Recall what alpha, beta and gamma radiation are.
Sort statements into alpha decay or beta decay.
State how mass number and atomic number change in each type of decay.

Warm Up

Fill the gap

Choose the correct word from the word bank to complete each sentence. Two words will NOT be used.

helium unstable proton electron transmutation gamma conserved neutron paper lead

Radioactive decay is the spontaneous breakdown of an nucleus. An alpha particle is a nucleus, written ⁴₂He. In beta-minus decay a turns into a proton, and a fast is fired out as the beta particle. When the number of protons changes, one element turns into another, a process called . High-energy radiation carries away energy but changes neither the mass number nor the atomic number. In every nuclear equation the total mass number and total atomic number are on both sides. The most penetrating radiation is stopped only by thick or concrete.

Your Turn

Sort it!

Write each statement from the pool into the correct box below. Each statement belongs to exactly one type of decay.

Emits ⁴₂He Emits ⁰_-1e Mass number drops by 4 Mass number stays the same Atomic number drops by 2 Atomic number rises by 1 A neutron becomes a proton Two protons and two neutrons leave Stopped by a sheet of paper Stopped by a sheet of aluminium Example: U-238 to Th-234 Example: C-14 to N-14

Alpha decay (α)

Beta-minus decay (β⁻)

Show What You Know

1. Describe what an alpha particle is made of, and state how the mass number and atomic number of a nucleus change when it emits one.

Recall 2 marks

2. List alpha, beta and gamma radiation in order from least penetrating to most penetrating, and name one material that stops each.

Recall 2 marks

Wrap Up

In one sentence, explain why losing an alpha or beta particle turns one element into a different element.