4.2.7
Half Lives & Ionising Radiation
Half-Life
Half-Life
The half-life is the average time taken for the number of radioactive nuclei to halve. The activity of a radioactive substance is measured in Becquerels (Bq).
Half-lives are predictable
Half-lives are predictable
- The radioactive decay of an individual atom is random and unpredictable.
- However, large groups of nuclei do normally behave in predictable ways.
Half lives are constant
Half lives are constant
- The half-life is the average time taken for the number of radioactive nuclei to halve.
- The half-life for any isotope of an element is constant.
- The half-life of unstable isotopes can be seconds or millions of years.
Measuring Half-Life
Measuring Half-Life
To find the half-life of a radioactive isotope, we must strip out the background radiation of the environment around us.
Calculation
Calculation
- The level of radiation due to substance = level of radiation with substance and background radiation - level of background radiation.
Equipment
Equipment
- We can work out the level of background radiation using a Geiger counter.
Ions and Ionising Radiation
Ions and Ionising Radiation
Alpha, beta and gamma radiation are all ionising radiation. Ionising radiation can break molecules into small particles called ions.
Ions are charged particles
Ions are charged particles
- Ions are particles that become charged by gaining or losing electrons.
Ions can cause cell damage
Ions can cause cell damage
- Ions can react in unusual ways.
- This can damage cells and complex chemical structures, such as DNA.
- The cell damage from ionising radiation can cause mutations. These mutations can lead to cancer.
1Energy
1.1Energy Changes
1.1.1Energy Stores
1.1.2Calculating Changes in Energy
1.1.3Changes in Kinetic Energy - Calculations
1.1.4Changes in GPE - Calculations
1.1.5Changes in EPE - Calculations
1.1.6Energy Transfers
1.1.7Mechanical Work Done
1.1.8Mechanical Work - Calculations
1.1.9Electrical Work Done
1.1.10Electrical Work Done- Calculations
1.2Energy Losses & Efficiency
2Electricity
2.1Electric Charge
2.2Resistance & Electrical Work
2.3Electric Circuits
2.4Electricity in Homes
2.5Static Electricity
3Particle Model of Matter
3.1States of Matter
3.2Heat
4Atoms & Radiation
4.1Atoms
4.2Radiation
4.2.1Radioactive Decay
4.2.2Radioactive Decay 2
4.2.3Types of Radioactive Emission
4.2.4Fission & Fusion
4.2.5Radioactive Decay Equations
4.2.6Radio. decay equations - Calculations
4.2.7Half Lives & Ionising Radiation
4.2.8Half Life - Calculations
4.2.9Uses & Dangers of Radiation
4.2.10Uses & Dangers of Radiation 2
4.2.11End of Topic Test - Atoms & Radiation
4.2.12Grade 9 - Radiation
4.2.13Exam-Style Questions - Radioactive Decay
5Forces
5.1Basics of Motion
5.2Forces
5.2.1Gravity
5.2.2Gravity - Calculations
5.2.3Resultant Forces
5.2.4Newton Second Law - Calculations
5.2.5Force Diagrams
5.2.6Free Body Diagrams - Calculations
5.2.7Stretching a Spring
5.2.8Hooke's Law
5.2.9Hooke's Law - Calculations
5.2.10Elastic Potential Energy
5.2.11Elastic Potential - Calculations
5.2.12Exam-Style Questions - Elastic Potential Energy
5.3Effects of Forces
6Waves
6.1Wave Basics
6.2Waves at a Boundary
6.3Sound Waves
6.4Electromagnetic Waves
7Magnetism
7.1Magnetism Basics
7.2Electromagnetism
Jump to other topics
1Energy
1.1Energy Changes
1.1.1Energy Stores
1.1.2Calculating Changes in Energy
1.1.3Changes in Kinetic Energy - Calculations
1.1.4Changes in GPE - Calculations
1.1.5Changes in EPE - Calculations
1.1.6Energy Transfers
1.1.7Mechanical Work Done
1.1.8Mechanical Work - Calculations
1.1.9Electrical Work Done
1.1.10Electrical Work Done- Calculations
1.2Energy Losses & Efficiency
2Electricity
2.1Electric Charge
2.2Resistance & Electrical Work
2.3Electric Circuits
2.4Electricity in Homes
2.5Static Electricity
3Particle Model of Matter
3.1States of Matter
3.2Heat
4Atoms & Radiation
4.1Atoms
4.2Radiation
4.2.1Radioactive Decay
4.2.2Radioactive Decay 2
4.2.3Types of Radioactive Emission
4.2.4Fission & Fusion
4.2.5Radioactive Decay Equations
4.2.6Radio. decay equations - Calculations
4.2.7Half Lives & Ionising Radiation
4.2.8Half Life - Calculations
4.2.9Uses & Dangers of Radiation
4.2.10Uses & Dangers of Radiation 2
4.2.11End of Topic Test - Atoms & Radiation
4.2.12Grade 9 - Radiation
4.2.13Exam-Style Questions - Radioactive Decay
5Forces
5.1Basics of Motion
5.2Forces
5.2.1Gravity
5.2.2Gravity - Calculations
5.2.3Resultant Forces
5.2.4Newton Second Law - Calculations
5.2.5Force Diagrams
5.2.6Free Body Diagrams - Calculations
5.2.7Stretching a Spring
5.2.8Hooke's Law
5.2.9Hooke's Law - Calculations
5.2.10Elastic Potential Energy
5.2.11Elastic Potential - Calculations
5.2.12Exam-Style Questions - Elastic Potential Energy
5.3Effects of Forces
6Waves
6.1Wave Basics
6.2Waves at a Boundary
6.3Sound Waves
6.4Electromagnetic Waves
7Magnetism
7.1Magnetism Basics
7.2Electromagnetism
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