1. Combined Science (1-9): Radioactivity Beta Decay and Nuclear Equations

2. Objectives:

3. Beta Decay and Nuclear Equations
Draw a line under last lesson’s work and write today’s title in your book...
28/11/2018
c/w
Beta Decay and Nuclear Equations

4. FLASHBACK
FLASHBACK: Explain the energy transfers that take place during the hydroelectric (dams) production of electrical energy [6 marks]

5. FLASHBACK- AFL
FLASHBACK: Explain the energy transfers that take place during the hydroelectric (dams) production of electrical energy [6 marks]
Water is up high so has high gravitational potential energy (GPE)
This is transformed into kinetic energy
Used to move the turbines
The kinetic energy of the turbines is transferred into kinetic energy of a coil
The spinning coil/generator then transforms the energy into electrical energy

6. Starter Activity +2 electron positron Very weak
Fill in the table with what you know. The blue row is completely new but you can probably predict it!
Nature
Mass
Charge
Ionising ability
Alpha (α) +2
Beta (β-)
electron
Beta (β+)
positron
Gamma (γ)
Very weak

7. Explore 4 +2 strong 1/1840 -1 weak +1 1/1840 weak
Ionising = capable of turning atoms into ions (by removing or adding electrons)
Nature
Mass
Charge
Ionising ability
Alpha (α)
Beta (β-)
electron
Beta (β+)
positron
Gamma (γ)
2 protons + 2 neutrons (helium nucleus) 4 +2
strong
1/1840 -1
weak +1
1/1840
weak
Electromagnetic wave
Very weak

8. Nuclear Decay
Remember, when an atom is unstable (radioactive), it releases this energy in the form of radiation. This process is random and cannot be predicted. This is called decay and changes the structure of the atom

9. First identify the number of protons and neutrons in a uranium atom
Nuclear Decay
Write a hypothesis of what you think will happen to the atomic structure of a uranium atom during decay U 92
236

10. Types of Nuclear Decay Alpha Decay Beta (-) Decay Beta (+) Decay
You will need to be able to identify the type of nuclear decay taking place by looking at what has happened to the mass and proton number of a radioactive element. This will build up to understanding nuclear equations
Alpha Decay
Beta (-) Decay
Beta (+) Decay
Gamma Decay

11. Alpha Decay
In alpha decay, the unstable nucleus loses 2 protons and 2 neutrons (a helium nucleus)
What effect would this have on the mass number and the atomic number?
Predict the products of alpha decay of uranium-235
This is a nuclear equation! Pretty simple really!

12. Beta (-) Decay
In beta minus (β-) decay, a neutron changes into a proton within the nucleus.
The mass stays the same, but there is now extra positive charge. (extra proton) so an electron is created to cancel out this charge.
Firstly, establish what effect this has on the mass number and on the atomic (proton) number ? e- +
Now using what you know about elements, use the periodic table to predict the result!

13. Beta (-) Decay
In beta minus (β-) decay, a neutron changes into a proton within the nucleus.
The mass stays the same, but there is now extra positive charge. (extra proton) so an electron is created to cancel out this charge. Np e-
235 + 93

14. Beta (β +) Decay
In beta positive (β+) decay, a proton changes into a neutron within the nucleus.
The mass stays the same, but there is now less positive charge. (extra proton) so a positron (like a positive electron!) is created to cancel out this charge.
Firstly, establish what effect this has on the mass number and on the atomic (proton) number ? β+ +
Now using what you know about elements, use the periodic table to predict the result!

15. Beta (β +) Decay
In beta positive (β+) decay, a proton changes into a neutron within the nucleus.
The mass stays the same, but there is now less positive charge. (extra proton) so a positron (like a positive electron!) is created to cancel out this charge. Pa β+
235 + 91

16. Support: Quick Trick! No Point Being Negative
Neutron  Proton is B Negative
People Need to Be Positive
Proton  Neutron is B positive

17. Gamma Decay
Gamma decay is the simplest! As it is only pure energy, it has no effect on the atomic structure (so no equation to learn!)
Discussion point: Where has this energy come from if there is no effect on atomic structure?

18. Individual Practice

19. 6 mark question!
Compare the nuclear rearrangements that occur in beta positive and beta minus decay [ 6 marks]

20. In beta minus decay, a neutron changes into a proton
6 mark question!
Compare the nuclear rearrangements that occur in beta positive and beta minus decay [ 6 marks]
In beta positive decay, a proton changes into a neutron
This causes the proton number to decrease by 1 but mass to stay the same
A positron is emitted
In beta minus decay, a neutron changes into a proton
This causes the proton number to increase by one but mass stays the same
An electron is emitted

21. Objectives: