Nuclear radiation
Welcome!
In this lesson, we will explore the concept of radioactive decay, a fundamental process that underpins the phenomenon of radioactivity.
the world of Nuclear Radiation
An exploration of the nucleus, radiation, and energy
Click on any of the lessons below to jump to that section, or click 'next' to start with the module introduction.
7. Radioactive Decay Concepts
1. Module Introduction
8. Decay Mathematics
2. Alpha and Beta Radiation
9. Background Radiation
3. Gamma Radiation and Comparison
10. Core Practical - Gamma Absorption
4. Nuclear Equations
11. Applications of Nuclear Radiation
5. Binding Energy
6. Nuclear Fission and Fusion
12. Review and Assessment
Next
pre-assessment: Let's check your knowledge!
Before we dive into nuclear radiation, let's check your existing knowledge with a few quick questions. Don't worry if you're unsure of some answers—this is just to help you identify what you already know and what we'll be learning together. Click each card to reveal the answers after you've had a chance to think about them.
ANSWER
ANSWER
ANSWER
ANSWER
Protons and neutrons (collectively called nucleons)
Alpha (α), beta (β), and gamma (γ) radiation
A substance is radioactive when its nucleus is unstable and emits radiation to become more stable.
Gamma radiation has the greatest penetrating power.
1. What particles make up the nucleus of an atom?
3. Name the three main types of radiation.
2. What is meant by the term "radioactive"?
4. Which type of radiation has the greatest penetrating power?
1. module introduction
learning objectives
After completing this module, you will be able to:
Apply radioactive decay equations to half-life calculations
Explain the properties of alpha, beta, and gamma radiation
Analyze gamma radiation absorption in different materials
Balance nuclear equations for different decay processes
Evaluate applications of nuclear radiation in medicine and industry
Calculate binding energy and relate it to nuclear stability
Explain the processes of nuclear fission and fusion
introducing radioactivity
What is Radioactive Decay?
Radioactive decay is the process by which unstable atomic nuclei lose energy by emitting radiation. This decay occurs naturally as these isotopes attempt to reach a more stable atomic configuration. The emitted radiation can take various forms, including alpha particles, beta particles, and gamma rays.
Why is it Important?
Understanding radioactive decay is crucial because it has significant implications in various fields, including nuclear physics, medicine, and environmental science. By studying this process, we can learn how isotopes behave over time, which is essential for applications such as cancer treatment, radiometric dating, and energy generation in nuclear reactors. Additionally, awareness of radioactive decay helps us manage the risks associated with radiation exposure.
Join us as we uncover the fascinating world of radioactivity and its critical impact on our understanding of the natural world and technological advancements!
Previous learning connection
This module builds on your previous understanding of atomic structure, isotopes, and nuclear forces.
Atomic Structure
Remember that atoms consist of a nucleus (containing protons and neutrons) surrounded by electrons. The number of protons determines the element.
Isotopes
Isotopes are atoms of the same element with different numbers of neutrons, giving them different mass numbers but the same atomic number.
Nuclear forces
The strong nuclear force holds nucleons (protons and neutrons) together, overcoming the electrostatic repulsion between protons at short distances.
Timeline
1898
1911
1900
1899
1896
1932
Check Your Understanding
Test your understanding of the introductory concepts before moving to the next module. Click each question to reveal the answer.
ANSWER
ANSWER
ANSWER
ANSWER
It revealed the nuclear model of the atom, showing that atoms have a small, dense, positively charged nucleus surrounded by mostly empty space occupied by electrons.
Ernest Rutherford identified alpha and beta radiation (1899), and Paul Villard discovered gamma radiation (1900).
Radioactive decay is the process by which unstable atomic nuclei lose energy by emitting radiation to become more stable.
Any three from:
2. Name the three scientists who identified the three main types of radiation.
4. Name three modern applications of nuclear radiation.
3. Why was Rutherford's gold foil experiment significant?
1What is radioactive decay?
1. types of nuclear radiation
types of radiation
In this lesson, we will delve into the various types of radiation, a key aspect of the phenomenon of radioactivity. Understanding these types is essential for grasping how they operate, their characteristics, and their effects on matter.
Click on the button below to watch an introductory video, "What is Radioactivity and Is It Always Harmful." Here, you'll explore the different forms of radiation—alpha, beta, and gamma radiation—how they are emitted during radioactive decay, and their unique properties. You'll also touch upon their applications and implications, especially in scientific and medical contexts.
Let’s embark on this journey to discover the fascinating world of radiation and its significance in both nature and technology!
what is an unstable nucleus?
Definition
How common?
Causes of Instability
Discover what makes an atomic nucleus unstable and how this impacts its behavior.
Explore how the prevalence of unstable nuclei has changed since the early formation of Earth and what that means today.
Learn about the factors that lead to nuclear instability and the role of protons and neutrons.
Structure of Nuclear Radiation
When unstable nuclei decay, they emit one or more types of radiation. To understand nuclear processes, we need to know the fundamental structure of each radiation type and how they change the nucleus.
Gamma (γ)
Beta (β)
ALPHA (α)
A beta particle is:- A high-speed electron (β⁻) or positron (β⁺)
- Created during decay (not pre-existing in nucleus)
- Result of neutron→proton conversion (β⁻)
- Or proton→neutron conversion (β⁺)
Gamma radiation is:- A high-energy photon (packet of electromagnetic energy)
- Has no mass or physical structure
- Pure energy with no charge
- Similar to light but much higher energy
An alpha particle consists of:- 2 protons
- 2 neutrons
- Identical to a helium nucleus (₂He⁴)
- Emitted as a complete unit from the nucleus
Element Transformation
Decay Origins
Radiation Structure
Reveal what an alpha particle is made of!
Uncover what gamma radiation actually is!
Discover the nature of beta particles!
Explore how the prevalence of unstable nuclei has changed since the early formation of Earth and what that means today.
Discover what makes an atomic nucleus unstable and how this impacts its behavior.
Explore the structure of each type of nuclear radiation
Learn how nuclear changes transform elements
Explore where these radiation particles originate from
understanding Alpha decay
What is Alpha Radiation?
Alpha radiation occurs when an unstable atom releases an alpha particle, which is made up of two protons and two neutrons. This type of radiation happens in heavy elements, like uranium and radium, when they need to shed mass to become more stable.
When Does It Occur?
Alpha radiation occurs when:
- An atom has too many protons or neutrons, making it unstable.
- The atom emits an alpha particle to lose mass and achieve a more balanced state.
understanding Beta decay
What is Beta Radiation?
Beta radiation occurs when a neutron in an unstable nucleus converts to a proton (or vice versa), emitting a high-speed electron (β⁻) and positron (β+) . Let's examine this process.
When Does It Occur?
Beta radiation happens when a nucleus has an imbalance between protons and neutrons. The type of beta decay depends on which particle is in excess.
Occurs in neutron-rich nuclei where the neutron-to-proton ratio is too high. A neutron converts to a proton, emitting an electron (β⁻) and an antineutrino. This is common in naturally occurring radioactive isotopes and fission products.
Occurs in proton-rich nuclei where the neutron-to-proton ratio is too low. A proton converts to a neutron, emitting a positron (β⁺) and a neutrino. This typically happens in artificially produced isotopes used in medical imaging (like PET scans).
Both processes adjust the neutron-to-proton ratio to move the nucleus toward greater stability.
understanding Gamma decay
What is Gamma Radiation?
Unlike alpha and beta radiation, gamma radiation is not a particle but a form of electromagnetic radiation – similar to light but with much higher energy. Let's explore its nature and how it's produced.
When Does It Occur?
Gamma radiation typically occurs :
- After alpha or beta decay, when the daughter nucleus is left in an excited state
- The nucleus needs to transition from a higher energy state to a lower energy state
- The nucleus releases excess energy without changing its composition (no change in atomic number or mass number)
Unlike alpha or beta decay, gamma emission doesn't transform the element or isotope - it only releases energy as the nucleus reaches a more stable energy configuration.
How does the Structure of radiation shape its Properties?
The structure of alpha, beta, and gamma radiation directly determines how they behave. Let's examine how three key properties relate to their fundamental structure.
Deflection in Fields
Penetration Ability
Ionizing Power
Explore how the prevalence of unstable nuclei has changed since the early formation of Earth and what that means today.
Discover what makes an atomic nucleus unstable and how this impacts its behavior.
Discover how particle structure affects ionizing ability
Explore why some radiation types penetrate more than other
See how mass and charge determine behavior in fields
Radiation Hazards and Protection
The hazard posed by each radiation type relates directly to its structure and properties. Understanding these connections helps explain appropriate safety measures.
gamma radiation
beta radiation
Alpha radiation
Explore how the prevalence of unstable nuclei has changed since the early formation of Earth and what that means today.
Discover what makes an atomic nucleus unstable and how this impacts its behavior.
Discover why alpha radiation is harmless outside but dangerous inside the body
Explore why beta radiation presents both external and internal risks
Learn why gamma radiation requires the most extensive protection measures
How does the Structure of radiation shape its Properties?
The structure of alpha, beta, and gamma radiation directly determines how they behave. Let's examine how three key properties relate to their fundamental structure.
Deflection in Fields
Penetration Ability
Ionizing Power
Explore how the prevalence of unstable nuclei has changed since the early formation of Earth and what that means today.
Discover what makes an atomic nucleus unstable and how this impacts its behavior.
Discover how particle structure affects ionizing ability
Explore why some radiation types penetrate more than other
See how mass and charge determine behavior in fields
what are the uses of radioactive decay?
alpha radiation
Gamma radiation
Beta Radiation
Discover how alpha radiation's unique properties make it perfect for smoke detection
Uncover how gamma radiation's penetrating power saves lives and improves industry
Explore how beta radiation helps measure materials and date ancient artifacts
properties of Nuclear RadiatioN
Nuclear radiation comes in three primary forms: alpha, beta, and gamma. Each type has distinct properties that determine its behavior and applications. Let's start by exploring the basic characteristics of these radiation types.
The Building Blocks: Nuclear Structure
There are three components of nuclear structure:
- Proton number (Z): Determines the element
- Neutron number (N): Affects stability
- Nucleon number (A): Total protons + neutrons
Knowledge check:
- Write the nuclear notation for the atom to the left
- What is the difference between this atom and Carbon-14?
Why Do Nuclei Decay?
Nuclear tug of war
There are two competing forces within a nucleus:- Strong nuclear force: attracts nucleons together
- Electromagnetic force: Pushes protons apart
The balance between these forces determines stability
Challenge: draw an image to demonstrate these forces in a nucleus
Instability could be caused by there being:- Too many neutrons
- Too few neutrons
- Too many neucleons in total (i.e. it's too heavy)
- Too much energy in the nucleus
how do nuclei decay?
Nuclear decay
- When a nucleus is unstable, it can decay by releasing energy and / or particles
- It will do this until it reaches a stable form, i.e. when the forces are balanced
Four types of nuclear decay
- Alpha radiation
- Beta-minus radiation
- Beta-plus radiation
- Gamma radiation
Important note:
Radioactive decay is random and spontaneous - it cannot be predicted
Alpha Decay: Shedding Weight
Key information
- Composition: 2 protons + 2 neutrons (helium nucleus)
- Emitted by: heavy, unstable nuclei
- Result: Z decreases by 2, A decreases by 4
Challenge: write a nuclear equation for the decay of Uranium-238
Beta plus Decay: The Neutron-electron Converter
Key information
- Composition: High-speed electron
- Occurs when: Too many neutrons
- Process: Neutron → Proton + Electron
- Result: Z increases by 1, A stays the same
Beta plus Decay: The Neutron-positron Converter
Key information
- Composition: High-speed electron
- Occurs when: Too many neutrons
- Process: Neutron → Proton + Electron
- Result: Z increases by 1, A stays the same
What are the Key Properties of Alpha Particles?
Alpha particles have the following properties:
- Relatively slow (5-10% speed of light)
- Large mass (4u)
- Double positive charge (+2e)
- Strong ionizing power
- Low penetration
gamma hazards
- External exposure: High risk (penetrates entire body)
- Internal exposure: Continues risk (passes through entire body)
- Protection: Dense shielding (lead/concrete), distance, time limits
- Low ionizing power but reaches all organs, causing widespread damage
rutherford's contributions
- Identified and named alpha and beta radiation
- Conducted the gold foil experiment revealing the nuclear model of the atom
- Discovered that radioactive elements can transform into other elements
- First artificially induced nuclear transmutation (1919)
- Established the concept of radioactive half-life
- Rutherford's work laid the foundation for nuclear physics and earned him the title "father of nuclear physics."
Beta Uses
- Thickness measurement in paper/plastic production
- Medical tracers
- Carbon dating
Connection to Next Module:
In the next module, we will:
- Examine the detailed properties of alpha radiation
- Explore beta radiation and its characteristics
- Compare different radiation types
- Understand their penetrating abilities and applications
ionising power
- Alpha (High): Large mass and +2 charge create many ions per mm
- Beta (Medium): Smaller mass and ±1 charge create fewer ions per mm
- Gamma (Low): No charge means infrequent interactions with matter
Real-life applications:
Nuclear physics impacts our daily lives in ways you might not expect:
- Medical diagnoses and cancer treatments
- Energy production in nuclear power stations
- Archaeological dating of ancient artifacts
- Food preservation techniques
- Industrial quality control and safety testing
- Space exploration power sources
alpha uses
- Smoke detectors (ionization enables detection)
- Static eliminators (ionizing ability neutralizes charge)
1900
Paul Villard discovered a third type of radiation, later named gamma (γ) rays, which had greater penetrating power than alpha or beta.
1. Nuclear notation for Carbon-12
2. Carbon-12 vs. Carbon-14: different neutron count
1932
James Chadwick discovered the neutron, completing our basic understanding of the components of the nucleus.
alpha hazards
- External exposure: Low risk (stopped by skin)
- Internal exposure: High risk (strong ionizing effect damages cells)
- Protection: Avoid ingestion/inhalation, basic barriers sufficient
- Hazardous when alpha emitters enter the body through wounds, breathing, or eating
beta hazards
- External exposure: Moderate risk (can penetrate skin causing burns)
- Internal exposure: Significant risk (ionizing ability damages surrounding tissue)
- Protection: Aluminum shielding, protective clothing, distance
- Less ionizing than alpha but more penetrating, presenting both external and internal hazards
How do parent NucleI change during radioactive decay?
When decay occurs, the parent nucleus changes:
- Alpha emission: parent nucleus loses 2 protons and 2 neutrons
- Beta-minus emission: a neutron changes into a proton in the parent nucleus
- Beta-plus emission: a proton changes into a neutron in the parent nucleus
- Gamma emission: the nuclear energy state of the parent nucleus changes
Since the element is determined by number of protons, alpha and beta decay create atoms of different elements.
hat is Beta-Plus (β⁺) Decay?
In beta-plus decay, a proton converts to a neutron, emitting a positron (the antimatter equivalent of an electron). This decreases the atomic number by 1 while keeping the mass number the same. The image below shows an example of this in the decay of carbon-10.
Note that, by effectively losing a proton, the daughter nucleus moves down the periodic table by one place. This is always the case in beta plus decay.
ionising power
- Alpha (High): Large mass and +2 charge create many ions per mm
- Beta (Medium): Smaller mass and ±1 charge create fewer ions per mm
- Gamma (Low): No charge means infrequent interactions with matter
1899
Ernest Rutherford identified two types of radiation: alpha (α) and beta (β). He found that they had different penetrating abilities and were deflected differently by electric and magnetic fields.
how common are unstable nuclei?
- Unstable nuclei were much more prevalent shortly after Earth formed, as many heavy elements were still in the process of decaying.
- Today, the number of naturally occurring unstable nuclei is significantly lower, primarily due to the natural decay processes that have occurred over billions of years.
- While some unstable isotopes remain, they are less common than during the early history of our planet.
penetrating ability
- Alpha (Low): Stopped by paper or skin due to strong interactions, due to high ionisation.
- Beta (Medium): Stopped by aluminum sheet or plastic, due to medium ionisation.
- Gamma (High): Requires lead or concrete for effective shielding, due to low ionisation.
1911
Rutherford's gold foil experiment led to the discovery of the nucleus, showing that atoms have a small, dense, positively charged center surrounded by mostly empty space.
What is beta minus (β⁻) decay?
Beta minus radiation occurs when a neutron in an unstable nucleus converts to a proton, emitting a high-speed electron (β⁻) and an antineutrino. This increases the atomic number by 1 while keeping the mass number the same.The image below shows an example of this in the decay of carbon-14.
Note that, by effectively gaining a proton, the daughter nucleus moves up the periodic table by one place. This is always the case in beta minus decay.
penetrating ability
- Alpha (Low): Stopped by paper or skin due to strong interactions, due to high ionisation.
- Beta (Medium): Stopped by aluminum sheet or plastic, due to medium ionisation.
- Gamma (High): Requires lead or concrete for effective shielding, due to low ionisation.
deflection in fields
- Alpha: Slight deflection (large mass despite +2 charge)
- Beta: Strong deflection (small mass with ±1 charge)
- Gamma: No deflection (no charge)
1898
Marie and Pierre Curie isolated two new radioactive elements: polonium and radium. Marie Curie coined the term "radioactivity" and received two Nobel Prizes for her work.
Definition
An unstable nucleus occurs when an atom has an imbalance in the number of protons and neutrons. This imbalance disrupts the strong nuclear force that holds the nucleus together, leading to instability.
1896
Henri Becquerel accidentally discovered radioactivity while working with uranium compounds. He found that uranium could expose photographic plates without light, indicating it emitted invisible radiation.
gamma uses
- Medical imaging (high penetration through body)
- Sterilization of medical equipment
- Industrial radiography (detecting flaws in metals)
Where does Radiation Come From?
Each type of radiation has a different origin:
- Alpha particles come from within the nucleus, formed from 2 protons and 2 neutrons that are ejected together
- Beta particles are newly created during decay (not pre-existing in the nucleus)
- Gamma rays represent released energy as the nucleus transitions to a more stable arrangement
Most unstable nuclei emit either an alpha OR beta particle, which may be followed by gamma ray emission.
deflection in fields
- Alpha: Slight deflection (large mass despite +2 charge)
- Beta: Strong deflection (small mass with ±1 charge)
- Gamma: No deflection (no charge)
what makes a nucleus unstable?
Many elements have isotopes that radioactive because their nuclei are unstable. This instability could be caused by any of the following:
- Excess protons: Too many protons can increase repulsion between them, weakening stability.
- Excess neutrons: An abundance of neutrons can lead to instability, as they don't contribute to the nuclear charge but affect the nuclear force.
- Heavy elements: Larger atoms with many protons and neutrons are more likely to be unstable due to the complexity of their nuclear structures.
An unstable nucleus emits radiation in order to become more stable.
What Radiation Protection Principles should scientists follow?
When working with radioactive substances, scientists should always apply the following principles:
- Time: Limit exposure duration
- Distance: Increase distance from source
- Shielding: Use appropriate materials based on radiation type
- Containment: Prevent internal exposure by containing radioactive materials
What are the Key Properties of beta Particles?
Beta particles have the following properties:
- Medium-sized mass (about 1/1840 of a proton)
- Charge of -1e (beta-minus) or +1e (beta-plus)
- Travels at high speeds (up to 90% of the speed of light)
- Medium penetration ability (stopped by a few mm of aluminum)
- Can travel several meters in air
- Moderate ionizing power (less than alpha but more than gamma)
- Strongly deflected by electric and magnetic fields due to their charge and small mass
What are the Key Properties of gamma radiation?
Gamma radiation has the following properties:
- High-energy electromagnetic radiation (photons) emitted from the nucleus
- No mass and no charge (pure energy)
- Travels at the speed of light (3 × 10⁸ m/s)
- Highest penetration ability of all radiation types
- Requires several cm of lead or concrete for effective shielding
- Can pass completely through the human body
- Lowest ionizing power (less than alpha and beta)
- Not deflected by electric or magnetic fields due to lack of charge
Building on Previous Knowledge
This lesson builds on your understanding of atomic structure and radioactive decay.
- Atomic structure: Atoms have a nucleus containing protons and neutrons, surrounded by electrons in energy levels. Alpha and beta radiation involve changes to the nucleus.
- Radioactive decay: Unstable nuclei undergo radioactive decay to reach a more stable configuration by emitting radiation.
AS Level Physics - Radiaoactive Decay
Erika Blomerus
Created on March 11, 2025
Start designing with a free template
Discover more than 1500 professional designs like these:
View
Memories Presentation
View
Pechakucha Presentation
View
Decades Presentation
View
Color and Shapes Presentation
View
Historical Presentation
View
To the Moon Presentation
View
Projection Presentation
Explore all templates
Transcript
Nuclear radiation
Welcome!
In this lesson, we will explore the concept of radioactive decay, a fundamental process that underpins the phenomenon of radioactivity.
the world of Nuclear Radiation
An exploration of the nucleus, radiation, and energy
Click on any of the lessons below to jump to that section, or click 'next' to start with the module introduction.
7. Radioactive Decay Concepts
1. Module Introduction
8. Decay Mathematics
2. Alpha and Beta Radiation
9. Background Radiation
3. Gamma Radiation and Comparison
10. Core Practical - Gamma Absorption
4. Nuclear Equations
11. Applications of Nuclear Radiation
5. Binding Energy
6. Nuclear Fission and Fusion
12. Review and Assessment
Next
pre-assessment: Let's check your knowledge!
Before we dive into nuclear radiation, let's check your existing knowledge with a few quick questions. Don't worry if you're unsure of some answers—this is just to help you identify what you already know and what we'll be learning together. Click each card to reveal the answers after you've had a chance to think about them.
ANSWER
ANSWER
ANSWER
ANSWER
Protons and neutrons (collectively called nucleons)
Alpha (α), beta (β), and gamma (γ) radiation
A substance is radioactive when its nucleus is unstable and emits radiation to become more stable.
Gamma radiation has the greatest penetrating power.
1. What particles make up the nucleus of an atom?
3. Name the three main types of radiation.
2. What is meant by the term "radioactive"?
4. Which type of radiation has the greatest penetrating power?
1. module introduction
learning objectives
After completing this module, you will be able to:
Apply radioactive decay equations to half-life calculations
Explain the properties of alpha, beta, and gamma radiation
Analyze gamma radiation absorption in different materials
Balance nuclear equations for different decay processes
Evaluate applications of nuclear radiation in medicine and industry
Calculate binding energy and relate it to nuclear stability
Explain the processes of nuclear fission and fusion
introducing radioactivity
What is Radioactive Decay?
Radioactive decay is the process by which unstable atomic nuclei lose energy by emitting radiation. This decay occurs naturally as these isotopes attempt to reach a more stable atomic configuration. The emitted radiation can take various forms, including alpha particles, beta particles, and gamma rays.
Why is it Important?
Understanding radioactive decay is crucial because it has significant implications in various fields, including nuclear physics, medicine, and environmental science. By studying this process, we can learn how isotopes behave over time, which is essential for applications such as cancer treatment, radiometric dating, and energy generation in nuclear reactors. Additionally, awareness of radioactive decay helps us manage the risks associated with radiation exposure.
Join us as we uncover the fascinating world of radioactivity and its critical impact on our understanding of the natural world and technological advancements!
Previous learning connection
This module builds on your previous understanding of atomic structure, isotopes, and nuclear forces.
Atomic Structure
Remember that atoms consist of a nucleus (containing protons and neutrons) surrounded by electrons. The number of protons determines the element.
Isotopes
Isotopes are atoms of the same element with different numbers of neutrons, giving them different mass numbers but the same atomic number.
Nuclear forces
The strong nuclear force holds nucleons (protons and neutrons) together, overcoming the electrostatic repulsion between protons at short distances.
Timeline
1898
1911
1900
1899
1896
1932
Check Your Understanding
Test your understanding of the introductory concepts before moving to the next module. Click each question to reveal the answer.
ANSWER
ANSWER
ANSWER
ANSWER
It revealed the nuclear model of the atom, showing that atoms have a small, dense, positively charged nucleus surrounded by mostly empty space occupied by electrons.
Ernest Rutherford identified alpha and beta radiation (1899), and Paul Villard discovered gamma radiation (1900).
Radioactive decay is the process by which unstable atomic nuclei lose energy by emitting radiation to become more stable.
Any three from:
2. Name the three scientists who identified the three main types of radiation.
4. Name three modern applications of nuclear radiation.
3. Why was Rutherford's gold foil experiment significant?
1What is radioactive decay?
1. types of nuclear radiation
types of radiation
In this lesson, we will delve into the various types of radiation, a key aspect of the phenomenon of radioactivity. Understanding these types is essential for grasping how they operate, their characteristics, and their effects on matter.
Click on the button below to watch an introductory video, "What is Radioactivity and Is It Always Harmful." Here, you'll explore the different forms of radiation—alpha, beta, and gamma radiation—how they are emitted during radioactive decay, and their unique properties. You'll also touch upon their applications and implications, especially in scientific and medical contexts. Let’s embark on this journey to discover the fascinating world of radiation and its significance in both nature and technology!
what is an unstable nucleus?
Definition
How common?
Causes of Instability
Discover what makes an atomic nucleus unstable and how this impacts its behavior.
Explore how the prevalence of unstable nuclei has changed since the early formation of Earth and what that means today.
Learn about the factors that lead to nuclear instability and the role of protons and neutrons.
Structure of Nuclear Radiation
When unstable nuclei decay, they emit one or more types of radiation. To understand nuclear processes, we need to know the fundamental structure of each radiation type and how they change the nucleus.
Gamma (γ)
Beta (β)
ALPHA (α)
A beta particle is:- A high-speed electron (β⁻) or positron (β⁺)
- Created during decay (not pre-existing in nucleus)
- Result of neutron→proton conversion (β⁻)
- Or proton→neutron conversion (β⁺)
Gamma radiation is:- A high-energy photon (packet of electromagnetic energy)
- Has no mass or physical structure
- Pure energy with no charge
- Similar to light but much higher energy
An alpha particle consists of:- 2 protons
- 2 neutrons
- Identical to a helium nucleus (₂He⁴)
- Emitted as a complete unit from the nucleus
Element Transformation
Decay Origins
Radiation Structure
Reveal what an alpha particle is made of!
Uncover what gamma radiation actually is!
Discover the nature of beta particles!
Explore how the prevalence of unstable nuclei has changed since the early formation of Earth and what that means today.
Discover what makes an atomic nucleus unstable and how this impacts its behavior.
Explore the structure of each type of nuclear radiation
Learn how nuclear changes transform elements
Explore where these radiation particles originate from
understanding Alpha decay
What is Alpha Radiation?
Alpha radiation occurs when an unstable atom releases an alpha particle, which is made up of two protons and two neutrons. This type of radiation happens in heavy elements, like uranium and radium, when they need to shed mass to become more stable.
When Does It Occur?
Alpha radiation occurs when:
understanding Beta decay
What is Beta Radiation?
Beta radiation occurs when a neutron in an unstable nucleus converts to a proton (or vice versa), emitting a high-speed electron (β⁻) and positron (β+) . Let's examine this process.
When Does It Occur?
Beta radiation happens when a nucleus has an imbalance between protons and neutrons. The type of beta decay depends on which particle is in excess.
Occurs in neutron-rich nuclei where the neutron-to-proton ratio is too high. A neutron converts to a proton, emitting an electron (β⁻) and an antineutrino. This is common in naturally occurring radioactive isotopes and fission products.
Occurs in proton-rich nuclei where the neutron-to-proton ratio is too low. A proton converts to a neutron, emitting a positron (β⁺) and a neutrino. This typically happens in artificially produced isotopes used in medical imaging (like PET scans).
Both processes adjust the neutron-to-proton ratio to move the nucleus toward greater stability.
understanding Gamma decay
What is Gamma Radiation?
Unlike alpha and beta radiation, gamma radiation is not a particle but a form of electromagnetic radiation – similar to light but with much higher energy. Let's explore its nature and how it's produced.
When Does It Occur?
Gamma radiation typically occurs :
Unlike alpha or beta decay, gamma emission doesn't transform the element or isotope - it only releases energy as the nucleus reaches a more stable energy configuration.
How does the Structure of radiation shape its Properties?
The structure of alpha, beta, and gamma radiation directly determines how they behave. Let's examine how three key properties relate to their fundamental structure.
Deflection in Fields
Penetration Ability
Ionizing Power
Explore how the prevalence of unstable nuclei has changed since the early formation of Earth and what that means today.
Discover what makes an atomic nucleus unstable and how this impacts its behavior.
Discover how particle structure affects ionizing ability
Explore why some radiation types penetrate more than other
See how mass and charge determine behavior in fields
Radiation Hazards and Protection
The hazard posed by each radiation type relates directly to its structure and properties. Understanding these connections helps explain appropriate safety measures.
gamma radiation
beta radiation
Alpha radiation
Explore how the prevalence of unstable nuclei has changed since the early formation of Earth and what that means today.
Discover what makes an atomic nucleus unstable and how this impacts its behavior.
Discover why alpha radiation is harmless outside but dangerous inside the body
Explore why beta radiation presents both external and internal risks
Learn why gamma radiation requires the most extensive protection measures
How does the Structure of radiation shape its Properties?
The structure of alpha, beta, and gamma radiation directly determines how they behave. Let's examine how three key properties relate to their fundamental structure.
Deflection in Fields
Penetration Ability
Ionizing Power
Explore how the prevalence of unstable nuclei has changed since the early formation of Earth and what that means today.
Discover what makes an atomic nucleus unstable and how this impacts its behavior.
Discover how particle structure affects ionizing ability
Explore why some radiation types penetrate more than other
See how mass and charge determine behavior in fields
what are the uses of radioactive decay?
alpha radiation
Gamma radiation
Beta Radiation
Discover how alpha radiation's unique properties make it perfect for smoke detection
Uncover how gamma radiation's penetrating power saves lives and improves industry
Explore how beta radiation helps measure materials and date ancient artifacts
properties of Nuclear RadiatioN
Nuclear radiation comes in three primary forms: alpha, beta, and gamma. Each type has distinct properties that determine its behavior and applications. Let's start by exploring the basic characteristics of these radiation types.
The Building Blocks: Nuclear Structure
There are three components of nuclear structure:
Knowledge check:
Why Do Nuclei Decay?
Nuclear tug of war
There are two competing forces within a nucleus:
- Strong nuclear force: attracts nucleons together
- Electromagnetic force: Pushes protons apart
The balance between these forces determines stabilityChallenge: draw an image to demonstrate these forces in a nucleus
Instability could be caused by there being:- Too many neutrons
- Too few neutrons
- Too many neucleons in total (i.e. it's too heavy)
- Too much energy in the nucleus
how do nuclei decay?
Nuclear decay
Four types of nuclear decay
Important note:
Radioactive decay is random and spontaneous - it cannot be predicted
Alpha Decay: Shedding Weight
Key information
Challenge: write a nuclear equation for the decay of Uranium-238
Beta plus Decay: The Neutron-electron Converter
Key information
Beta plus Decay: The Neutron-positron Converter
Key information
What are the Key Properties of Alpha Particles?
Alpha particles have the following properties:
gamma hazards
rutherford's contributions
Beta Uses
Connection to Next Module:
In the next module, we will:
ionising power
Real-life applications:
Nuclear physics impacts our daily lives in ways you might not expect:
alpha uses
1900
Paul Villard discovered a third type of radiation, later named gamma (γ) rays, which had greater penetrating power than alpha or beta.
1. Nuclear notation for Carbon-12
2. Carbon-12 vs. Carbon-14: different neutron count
1932
James Chadwick discovered the neutron, completing our basic understanding of the components of the nucleus.
alpha hazards
beta hazards
How do parent NucleI change during radioactive decay?
When decay occurs, the parent nucleus changes:
Since the element is determined by number of protons, alpha and beta decay create atoms of different elements.
hat is Beta-Plus (β⁺) Decay?
In beta-plus decay, a proton converts to a neutron, emitting a positron (the antimatter equivalent of an electron). This decreases the atomic number by 1 while keeping the mass number the same. The image below shows an example of this in the decay of carbon-10.
Note that, by effectively losing a proton, the daughter nucleus moves down the periodic table by one place. This is always the case in beta plus decay.
ionising power
1899
Ernest Rutherford identified two types of radiation: alpha (α) and beta (β). He found that they had different penetrating abilities and were deflected differently by electric and magnetic fields.
how common are unstable nuclei?
penetrating ability
1911
Rutherford's gold foil experiment led to the discovery of the nucleus, showing that atoms have a small, dense, positively charged center surrounded by mostly empty space.
What is beta minus (β⁻) decay?
Beta minus radiation occurs when a neutron in an unstable nucleus converts to a proton, emitting a high-speed electron (β⁻) and an antineutrino. This increases the atomic number by 1 while keeping the mass number the same.The image below shows an example of this in the decay of carbon-14.
Note that, by effectively gaining a proton, the daughter nucleus moves up the periodic table by one place. This is always the case in beta minus decay.
penetrating ability
deflection in fields
1898
Marie and Pierre Curie isolated two new radioactive elements: polonium and radium. Marie Curie coined the term "radioactivity" and received two Nobel Prizes for her work.
Definition
An unstable nucleus occurs when an atom has an imbalance in the number of protons and neutrons. This imbalance disrupts the strong nuclear force that holds the nucleus together, leading to instability.
1896
Henri Becquerel accidentally discovered radioactivity while working with uranium compounds. He found that uranium could expose photographic plates without light, indicating it emitted invisible radiation.
gamma uses
Where does Radiation Come From?
Each type of radiation has a different origin:
- Alpha particles come from within the nucleus, formed from 2 protons and 2 neutrons that are ejected together
- Beta particles are newly created during decay (not pre-existing in the nucleus)
- Gamma rays represent released energy as the nucleus transitions to a more stable arrangement
Most unstable nuclei emit either an alpha OR beta particle, which may be followed by gamma ray emission.deflection in fields
what makes a nucleus unstable?
Many elements have isotopes that radioactive because their nuclei are unstable. This instability could be caused by any of the following:
An unstable nucleus emits radiation in order to become more stable.
What Radiation Protection Principles should scientists follow?
When working with radioactive substances, scientists should always apply the following principles:
What are the Key Properties of beta Particles?
Beta particles have the following properties:
What are the Key Properties of gamma radiation?
Gamma radiation has the following properties:
Building on Previous Knowledge
This lesson builds on your understanding of atomic structure and radioactive decay.