1. Can you look through your books and read the comments?
Do now!
Can you look through your books and read the comments?
Can you also look through the tests and make sure that Mr Porter has added the marks up correctly?

2. Today’s lesson Recall for radioactive emissions; their nature,
their relative ionising effects,
their relative penetrating abilities.
Describe the deflection of α-particles, β-particles and γ-rays in electric fields and magnetic fields.
Interpret their relative ionising effects.
Use equations (involving words or symbols) to represent changes in the composition of the nucleus when particles are emitted.

3. You’ll learn about some really weird ones in year 13!
3 types of particle
You’ll learn about some really weird ones in year 13!
There are 3 (at least in IGCSE!) types of particles that can be ejected from an unstable nuclei.

4. Alpha particles
Hi! α

5. He Alpha particles 2+ 4 2 2 protons and 2 neutrons joined together
The same as the nucleus of a helium atom
Stopped by paper or a few cm of air
Highly ionising
Deflected by electric and strong magnetic fields 2+ 4 He 2

6. α Th U + Alpha Decay 231 235 90 92 Atomic mass goes down by 4
Atomic number goes down by 2

7. Beta particles
Yo! β

8. e Beta particles -1 Fast moving electrons
Stopped by about 3 mm of aluminium
Weakly ionising
Deflected by electric and magnetic fields e -1

9. Beta decay
In the nucleus a neutron changes into an electron (the beta particle which is ejected) and a proton (which stays in the nucleus)
During beta decay the mass number stays the same but the proton number goes up by 1. Th 90
231 e Pa 91
231 + -1

10. Gamma rays
Hola!

11. Gamma rays High frequency electromagnetic radiation
Stopped by several cm of lead
Very weakly ionising
NOT affected by electric or magnetic fields

12. Gamma rays
Associated with alpha decay α Th 90
231 U 92
235 +

13. Penetration

14. Deflection by electric fields

15. Deflection by magnetic fields

16. Summary – stick in! Type of particle Symbol What is it? Charge
Penetrating power
Ionization
Deflection by elec and mag fields
Other
Alpha α
A helium nucleus (2 protons and 2 neutrons)
+ 2
Stopped by paper or several cm of air
Strongly
Small deflection
The most dangerous INSIDE the body
Beta β
A fast moving electron
- 1
Stopped by 3 mm of Aluminium
Weakly
Large deflection
Gamma γ
A photon of high frequency electromagnetic radiation
None
Stopped by several cm of lead
No deflection

17. Questions!
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