Chemistry AS EL CI 2.2
- Created by: A.B.
- Created on: 22-10-13 20:04
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- EL Nuclear Reactions CI 2.2 SL EL1 EL3
- Radioactive Isotopes
- Some isotopes have unstable nuclei
- Results in isotope being radioactive
- Emission
- Capable of knocking electrons out of atoms
- Referred to as ionising radiation
- Produced spontaneously by radioactive nuclei
- Types
- alpha
- Helium nuclei
- Relative charge of 2+
- Lose 2 protons and 2 neutrons from nucleus
- Stopped by paper (or skin)
- Low deflection due to mass
- Helium nuclei
- beta
- electron
- Relative charge or 1-
- Gain one proton lose one neutron from nucleus.
- 1 neutron is converted into a proton and an electron which is ejected from the nucleus.
- Stopped by aluminium foil
- High deflection in electric field
- electron
- gamma
- Electromagnetic radiation
- Charge of 0
- No change in nucleus
- Stopped by lead sheet
- No deflection in electric field
- alpha
- Capable of knocking electrons out of atoms
- Dangerous and can cause cancer
- Some isotopes have unstable nuclei
- Equations for radioactive decay
- With alpha and beta radiation, the atomic number changes and a new element is formed.
- Look up the symbol in the periodic table
- With alpha and beta radiation, the atomic number changes and a new element is formed.
- Half-life
- Time taken for half the nuclei in a sample to decay
- Fixed for any given radioisotope
- Not affected by temperature
- Can be used to date archaeological artefacts made from living things.
- Time taken for half the nuclei in a sample to decay
- Tracers
- Radioactive isotopes whose decay is monitered
- Can be used in medicine to aid diagnosis
- Tracers are relatively safe - small doses limit exposure and benefits outweigh risks.
- Nuclear Fusion
- Joining of 2 or more nuclei to form a heavier nucleus of a new element.
- High temperatures and pressures
- Provide energy needed to overcome repulsion
- Occurs during star formation
- Radioactive Isotopes
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