Stable and unstable nuclei Flashcards
Which interaction is responsible for decay in the nucleus?
The weak interaction.
What force holds the atom together?
The strong force
What are the three main forces acting in the nucleus?
1) Electromagnetic force- causes the positively charged protons in the nucleus to repel 2) Gravitational- attraction between nucleons due to mass 3) Strong nuclear- mainly attractive force that holds the nucleus together
Name the four fundamental forces.
Gravity, Electromagnetic force, Strong nuclear force, Weak nuclear force
What force is responsible for keeping the nucleus together?
Strong nuclear force
Which type of particles experience the strong nuclear force?
Hadrons (mesons & barions) but leptons do not
What is the short range attraction of the strong nuclear force?
3 x 10-15m (or 3 femtometers)
What is the short range repulsion of the strong nuclear force?
0.5 x 10-15m (or 0.5 femtometers)
How does the strong nuclear force change at different nucleon separations?
Repulsive for very small separations- up to 0.5 fm Attractive up to 3fm After 3 fm - falls towards 0
What is fm metres?
1fm=1*10^15
What are alpha particles?
2 protons and 2 neutrons (helium nucleus)
What are beta particles?
A high speed electron
Up to what distance is the strong force repulsive? Give the unit as well.
0.5fm
In what range is the strong force attractive? Give the unit as well.
0.5-4fm
What two words describe radioactive decay? (They begin with R and S)
Random and spontaneous
Why do atoms decay?
To become stable.
Can atoms decay more than once to become stable?
Yes!
What is alpha decay?
2 protons and 2 neutrons
What is beta decay?
A fast moving electron.
What does a neutron split to become in Beta minus decay?
A proton, electron and antineutrino.
What happens to the proton, nucleon and neutron number in Beta minus decay?
Proton Number: increases by one. Neutron number: falls by one. Nucleon number: stays the same.
What is the role of the anti neutrino in Beta minus decay?
To conserve momentum.
What properties belong to the neutrino?
- No charge - Not affected by electrostatic force - Tiny mass - Millions pass through your body every second!
What is gamma?
A photon of energy
What properties does gamma have?
- Zero charge -Zero mass
What is the purpose of gamma?
It is released to channel energy away from an excited nucleus.
What are gamma rays?
Photons
Which particles are emitted in beta-plus decay?
A neutron, a positron and an electron neutrino.
What are the three types of nuclear decay?
Alpha, beta and gamma decay.
What is the equation for alpha decay?
What is the equation for beta decay?
