Nuclear Review | Show Me The Physics

Fill in the Blank Notes

Summary

Balance equations: top numbers (A) and bottom numbers (Z) must match on both sides.

Penetration: alpha < beta < gamma.

Fission splits heavy nuclei; fusion joins light nuclei. Both turn a little mass into a lot of energy.

Nuclear vs. chemical: millions of times more energy per atom.

Explore

Pick a starting nucleus, then press a decay button. Watch the protons, neutrons, and notation change.

Mixed Practice

Problem 1

Complete: 23490Th → ? + 0−1e

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23491Pa (protactinium-234)

Problem 2

Complete: 23892U → 23490Th + ?

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42He — an alpha particle

Problem 3

Complete: 116C → 115B + ?

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0+1e — a positron

Problem 4

A fossil has 25% of its original carbon-14 left (half-life 5,730 years). How old is it?

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100% → 50% → 25% = 2 half-lives = 11,460 years

Problem 5

A worker needs to shield a source of gamma rays. Would a sheet of aluminum be enough? Explain.

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No. Gamma rays have no charge and no mass, so they pass through aluminum. Thick lead or concrete is needed.

Problem 6

Draw a model of what happens to the nucleus in beta decay.

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Inside the nucleus, one neutron changes into a proton, and an electron is shot out. The mass number stays the same and the atomic number goes up by 1, so the element changes to the next one on the periodic table.

Check Your Understanding

6 quick questions — pick an answer to see if you’re right.

1. Which particle is the same as a helium-4 nucleus?

2. 146C → 147N + ? The missing particle is

3. Which type of radiation is the most penetrating?

4. Fusion and fission both release energy because

5. Which statement compares nuclear and chemical energy correctly?

6. After 3 half-lives, what fraction of a radioactive sample is left?

NYSSLS Regents Practice · Nuclear · Mixed Review

Radon in the Basement

Radon-222 is a radioactive gas produced naturally by the decay of uranium in soil. It can collect in basements. Radon-222 has a half-life of 3.8 days and decays by emitting alpha particles.

Radon is most dangerous when it is breathed in. Which statement explains this?

▶ Want a challenge? Open 6 more Regents-style questions (harder · mixed formats)

Challenge score: 0 / 6

Multiple choice

C1. Radon-222 (²²²₈₆Rn) emits an alpha particle. What is produced?

Support or Refute · Justify

C2. A homeowner makes the following claim.

Claim: Radon-222 has a half-life of only 3.8 days, so if I close up my basement for a few weeks, the radon problem will disappear on its own.

Place a check mark in either the Support or Refute box. Justify your response.

Support Refute

Substitute values

C3. A sealed sample of basement air contains 3.2 × 10⁶ radon-222 atoms. Substitute numerical values into mathematical representations that can be used to determine the number of radon atoms remaining after 19 days. Then calculate the number.

n = t = dT_1/2 = d = N = ( × 10⁶ atoms)(½)ⁿ = × 10⁵ atoms

Select all that apply

C4. Place a check mark in three boxes to indicate properties of the alpha particles emitted by radon-222.

They have no electric charge. They carry a charge of +2e. They are stopped by a sheet of paper or the outer layer of skin. They are high-energy photons that travel at the speed of light. Each one consists of 2 protons and 2 neutrons. They are the most penetrating type of nuclear radiation.

Multiple choice

C5. Which home solution best reduces radon exposure?

Constructed response

C6. The polonium-218 (²¹⁸₈₄Po) produced by radon decay is also an alpha emitter, with a half-life of about 3 minutes. Write the nuclear equation for the alpha decay of polonium-218, identify the daughter nucleus, and explain why breathing in radon also exposes the lungs to polonium’s alpha particles.

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