Why are some atomic nuclei unstable?
= and imbalance in the forces within the nucleus
Example :carbon-14 is an isotope of carbon which is unstable, it has two extra neutrons compared to stable carbon-12
Why are some isotopes unstable?
= becuase of their large size or becuase they have too many or to few neutrons
What do unstable nuclei emit?
= radiation to become more stable - can be in the from of high energy particle or wave
How does editing radiation help make the nucleus more stable?
= as radiation moves away form nucleus it take some energy with it which reduces overall energy of the nucleus and makes it more stable
What is the process of emitting radiation known as?
= radioactive decay
True or false - radioactive decay is random.
= true
What different types of radiation can be emitted?
= alpha, beta, gamma and neutrons
What are alpha particles?
- is the same as a helium nucleus - twin protons and two neutrons
- they have a charge of +2 which means they can be affected by an electric field
What are beta particles?
- they are fast moving electrons
- they are produced in nuclei when a neutron changes into a proton and an electron
- they have a charge of -1
- means they can be effected by electrical field
Why can alpha and beta partials be affected by an electrical field?
= they both have a net electrical charge
What are gamma rays?
- gamma rays are electromagnetic waves
- they have the highest energy of the different types of electromagnetic waves and have no charge
What is the activity?
- sources of radiation decay at different rates which are defined by their activity
- the activity is defined as : the rate at which the unstable nuclei from a source of radiation decays
What is activity measured in?
= becquerels - Bq
What is 1Bq equal to?
= 1 nucleus in the source decaying in 1 second
What is used to detect radiation?
= Geiger- muller tube
How does it work?
- within it, ions are created by radiation passing through it
- can be connected to a Geiger counter
- this counts the ions created in the Geiger- muller tube
What is count-rate?
= the number of decays recorded each second by a detector
What is alpha decay?
- during alpha decay an alpha particle is emitted from an unstable nucleus
- a completely new element is created
- the mass and atomic number change : mass number decreases by 4 and the atomic number decreases by 2
- the charge on the nucleus also decreases by two because protons have a charge of +1 each - become -2
What is beta decay?
- during beta decay a neutron changes into a proton and an electron
- a new element is formed because atomic number changes
- it has a mass number of 0 as an electron has a tiny mass compared to neutrons and protons
- therefore madd number remains the same
- the electron has an atomic number of -1 which means the new nuclei will increase its atomic number by 1 in order to maintain the overall atomic number before and after
What is gamma decay?
- during a gamma ray is emitted form an unstable nucleus
- the process makes the nucleus less energetic but does not change its structure
- has no mass or charge
