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Questions and Answers
Who discovered radioactivity?
Who discovered radioactivity?
Which elements did Pierre and Marie Curie isolate from pitchblende?
Which elements did Pierre and Marie Curie isolate from pitchblende?
What type of radiation consists of groups of two protons and two neutrons?
What type of radiation consists of groups of two protons and two neutrons?
Which particle has the lowest penetrating power?
Which particle has the lowest penetrating power?
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What occurs to a neutron in the process of beta decay?
What occurs to a neutron in the process of beta decay?
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Which type of radiation is characterized by high penetrating ability and is not deflected by electric or magnetic fields?
Which type of radiation is characterized by high penetrating ability and is not deflected by electric or magnetic fields?
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What is the primary function of americium-241 as mentioned in relation to its applications?
What is the primary function of americium-241 as mentioned in relation to its applications?
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Which element is known for emitting beta particles and is used in carbon dating?
Which element is known for emitting beta particles and is used in carbon dating?
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Which type of radiation is considered the most dangerous due to its penetrating ability?
Which type of radiation is considered the most dangerous due to its penetrating ability?
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What is a key difference between chemical reactions and nuclear reactions?
What is a key difference between chemical reactions and nuclear reactions?
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What does the half-life of an element represent?
What does the half-life of an element represent?
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How much Carbon-14 will remain after two half-lives if starting with 10g?
How much Carbon-14 will remain after two half-lives if starting with 10g?
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Which statement accurately describes what occurs in nuclear reactions?
Which statement accurately describes what occurs in nuclear reactions?
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In the decay of Carbon-14, what is the product formed after one half-life?
In the decay of Carbon-14, what is the product formed after one half-life?
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What is the half-life of Carbon-14?
What is the half-life of Carbon-14?
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Which statement correctly describes the formation of new elements during nuclear reactions?
Which statement correctly describes the formation of new elements during nuclear reactions?
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What is the primary use of Iodine-131 in medicine?
What is the primary use of Iodine-131 in medicine?
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Which of the following best describes radiocarbon dating?
Which of the following best describes radiocarbon dating?
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What half-life corresponds to the decay of Carbon-14?
What half-life corresponds to the decay of Carbon-14?
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What fraction of caesium-137 remains after three half-lives?
What fraction of caesium-137 remains after three half-lives?
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How does gamma radiation relate to the use of radioisotopes in food safety?
How does gamma radiation relate to the use of radioisotopes in food safety?
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Which particle is emitted during the beta decay of Carbon-14?
Which particle is emitted during the beta decay of Carbon-14?
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What property is characteristic of beta particles?
What property is characteristic of beta particles?
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What is a common application of Americium-241?
What is a common application of Americium-241?
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Study Notes
Radioactivity
- Radioactivity was discovered by Henri Becquerel, a French physicist.
- He was studying the effect of sunlight on uranium salts.
- He left uranium salts on a photographic plate, wrapped in black paper, in the dark.
- He found the plate was fogged in the area near the uranium salt. This meant radiation was emitted.
- Marie and Pierre Curie further investigated uranium salts.
- They isolated the elements polonium and radium from pitchblende (a uranium ore).
Nature of Radioactive Radiation
- Three types of radiation were discovered based on how they behave in electric and magnetic fields.
Alpha Particles
- Groups of two protons and two neutrons stuck together.
- Carry a double positive charge, represented as ⁴₂He.
- Emitted from the unstable nucleus of a radioactive element.
- Thrown out of the nucleus as it changes to a more stable nucleus.
- Example: ²³⁸₉₂U → ⁴₂He + ²³⁴₉₀Th
- Relatively large mass.
- Travel slower than other types of radiation.
- Low penetrating power, stopped by a few centimetres of air or paper.
- Used in smoke detectors (Americium-241).
- Helium is an alpha particle.
Beta Particles
- Fast-moving electrons.
- Formed when a neutron in an unstable nucleus changes into a proton and an electron.
- The electron is ejected from the nucleus.
- Example: ¹⁴₆C → ¹⁴₇N + ⁰₋₁e
- Lighter than alpha particles, so they travel faster.
- More penetrating than alpha particles.
- Carbon-14 emits beta particles and is used in carbon dating.
Gamma Radiation
- High-energy electromagnetic radiation.
- Does not consist of charged particles.
- Not deflected by electric or magnetic fields.
- Emitted by unstable nuclei to lose surplus energy.
- Very high penetrating power; can penetrate through bricks and metal.
- Stopped by thick slabs of lead.
- Most dangerous type of radiation due to its penetrating power.
- Used in radiotherapy (Cobalt-60).
Nuclear Reactions
- Alter the composition, structure, or energy of an atomic nucleus.
- Chemical reactions involve changes in electrons, while nuclear reactions involve changes in the nucleus.
- Key differences in chemical vs nuclear reactions:
- Chemical involve electrons, nuclear does not
- Chemical does not form new elements, nuclear does
- Chemical does not release nuclear radiation, nuclear does
- Chemical breaks and forms bonds, nuclear does not
Half-Life
- The time taken for half of the nuclei in a given sample to decay.
- Radioactive isotopes decay at their own rates.
- Scientists use half-life to compare decay rates of radioisotopes.
Uses of Radioisotopes
- Medical: Gamma rays to kill cancerous cells, sterilize instruments, measure iodine uptake by thyroid.
- Archaeological: Radiocarbon dating to determine the age of objects containing carbon by measuring the ratio of Carbon-12 to Carbon-14.
- Agricultural: Studying fertilizer uptake by plants.
- Food Irradiation: Treating food with gamma rays to kill disease-carrying organisms.
- Smoke Alarms: Americium-241 detects smoke.
Exam Questions (2013 & 2011)
- Caesium-137: Released into the atmosphere after Japanese nuclear reactor damage. Decays by beta-particle emission with a half-life of 30 days.
- Isotopes: Atoms of the same element with the same atomic number but different mass numbers due to differing neutron numbers.
- Radioactivity: Spontaneous random decay of a nucleus to release alpha (α), beta (β), or gamma (γ) radiation.
- Radioisotope: Radioactive isotope.
- Carbon-14 decay: ¹⁴₆C → ¹⁴₇N + ⁰₋₁e
- Radiocarbon dating: Technique to determine the age of an object containing carbon by measuring the ratio of Carbon-14 to Carbon-12.
- Oldest shoe: Radiocarbon dating shows the shoe to be 5500 years old. Carbon-14 content changed over time.
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Description
Explore the fascinating world of radioactivity, from its discovery by Henri Becquerel to the essential contributions of Marie and Pierre Curie. Learn about the nature of radioactive radiation and the different types, including alpha particles. This quiz will test your knowledge on these significant scientific milestones.
