2. Stable and Unstable Nuclei Flashcards
Name the 3 forces in the nucleus
- Electromagnetic force
- Gravitational force
- Strong nuclear force
What is the electromagnetic force in the nucleus?
The force that causes the positively charged protons to repel each other
What is the gravitational force in the nucleus?
The force that causes all the nucleons in the nucleus to attract each other due to their mass
Is the repulsion of the electromagnetic force or the gravitational attraction bigger?
The repulsion of the electromagnetic force
What would happen if there were only the electromagnetic and gravitational forces?
The nucleus would collapse because the nucleons would fly apart
What force holds the nucleus together?
Strong nuclear force
Convert 1 fm (femtometres) to metres
1 fm = 1 x 10^-15 m (the size of a nucleus)
What is the range of repulsion of the strong nuclear force?
< 0.5 fm
What is the range of attraction of the strong nuclear force?
Between 0.5 fm and 3 fm
When can alpha decay happen?
When the atoms are very big (more than 82 protons)
What is released during alpha decay?
An alpha particle
What is the range of an alpha particle?
A few cm in the air
Name the 3 ways an alpha particle’s range can be observed
- Cloud chamber
- Geiger counter
- Spark counter
How does a cloud chamber work?
By observing the tracks left by alpha particles
How do the Geiger and spark counters work?
By measuring the ionising radiation
i.e. if you bring the counter up close to an alpha source and then slowly move away, the count rate will drop after a few centimetres
