What is the symbol for:
- an element
- The mass number
- Atomic number
- X
- A
- Z
What is:
Radioactive decay?
The spontaneous transformation of an unstable nucleus into a more stable one by the release of radiation. It is a random process which means that one cannot know what nucleus will decay or when it will decay becuase it is down to chance
What are the different:
Decay processes?
Why do they occur?
- Alpha - too heavy nucleus
- Beta - the atom is too unstable
- Gamma - there is an excess of energy
- Neutron radiation - (not done yet)
Characteristics of:
Alpha radiation
- Happens when an atom has a too heavy nucleus
- Highly ionising
- Weak penetrating leading to it travelling very small distances, and is stopped by a sheet of paper
- emmits a Helium nucleus
- Equation: ZAX -> (X-4a -2Z) + a
Characteristics of:
Beta radiation
- Happens when an atom is too far away from the line of stability
- A neutron is turned into a proton and emits a beta particle (electron)
- Moderately ionising and moderately penetrating, and are stopped by a sheet of aluminum
- Equation: ZAX -> (X A Z+1) + e-
Characteristics of:
Gamma radiation
- A wave that contains energy but no mass
- Lowly ionising and highly penetrating
- Stopped by many centimetres of lead
- Released when there is excess energy
What:
Holds the nucleus together
Strong nuclear force for nucleons, which acts on very small distances
Why is it impossible to:
Predict radioactive decay?
Because it is a random process
Why do atoms:
Go through radioactive decay
To become more stable as the atomic number and therefore element will change
What are the different:
Sources of background radiation
50 percent radon gas
14 gamma rays from the ground
10 cosmic rays
12 food
12 medical
1 other
What is:
A half life
The time it takes for half of the nuclei of unstable atoms to undergo radioactive decay
Applications of:
Radioactivity
Alarms, cancer treatment, measuring thickness and imaging
LEARN SYMBOLS BETA GAMMA ALPHA
What is:
irradiation
When an object or person is exposed to radiation
What is:
Contamination
When a radioactive source is in contact with an object of person. The radioactive substance rather than the emissions are present. THe object remains radioactive until the contamination is removed or decays naturally.
