Atomic structure Flashcards
What happens in nuclear fission?
The nucleus splits
Describe the process of nuclear fission
(Long answer question)
1.The unstable nucleus absorbs a neutron.
2. This causes the nucleus to split ( undergo fission).
3. When the nucleus splits, it forms two smaller nuclei equal in size. It also releases two or three neutrons and gamma radiation.
4. This process causes the neutrons to be absorbed and trigger fission again.
5. The repeating process of fission is named a chain reaction.
When is a controlled chain reaction used
In a nuclear reactor when releasing energy
What is nuclear fusion
To light nuclei are joined to form a heavier nucleus
What can the mass of the nucleus be converted into
Energy which is released as radiation
What radius do atoms have
1x10^-10 m
Do energy levels further from the nucleus have higher or lower energy than those close to the nucleus
Energy levels further from the nucleus are at a high energy
What happens if an atom absorbs electromagnetic radiation
An electron can move to a higher energy level
What are isotopes
The same element but with different numbers of neutrons
If an isotope has an unstable nucleus what must it do to become stable
Give out radiation
What processes giving out radiation
Radioactive decay
What is activity?
Rate of nuclei decay.
What’s the rate of nuclei decay measured in
Bequerel (Bq)
What is Count rate
The number of decays each second by a detector
Give an example of a detector
Geiger- Muller tube
What are alpha particles
Two neutrons and two electrons
What type of nucleus does an alpha particle have
A helium nucleus
What is a beta particle
A high speed electron
What is gamma radiation
Rays of electromagnetic radiation
What are the properties of alpha
5cm range in air
Penetrated by paper
Very strong ionising power
What are the properties of beta
15 cm range in air
Penetrated by a few millimetres of aluminium
Quite strong ionising power
What are the properties of gamma
Several meters range in air
Penetrated of several centimetres of lead
Weak ionising power
What happens during alpha decay
The atomic number decreases by 2
Mass number decreases by 4
What happens during beta decay
Atomic number increases by 1
