1.2 Stable and unstable nuclei

strong nuclear force

keeps protons and neutrons in the nucleus together

3 characteristics of the strong nuclear force

1. range of 3-4 fm

2. same effect between any nucleons

3. repulsive at separations less than 0.5 fm

Why is the strong nuclear force repulsive at separation of less than 0.5 fm?

prevents neutrons and protons being pushed into each other

What do alpha particles consist of?

2 protons

2 neutrons

mass number of an alpha partcile

4

atomic number of an alpha particle

2

What do beta particles consist of?

fast moving electrons

The charge of a beta particle is __________ and _____________ to that of a proton

equal

opposite

How does beta minus occur?

a neutron changes into a proton

What is emitted when a neutron changes into a proton?

1. beta minus

2. antineutrino

The atomic number of a particle __________ by _ when beta minus is emitted.

increases

1

What does gamma radiation consist of?

EM radiation

Gamma radiation is released by an ___________ nucleus

unstable

gamma particle can pass through ________ _________ __________

thick metal plate

gamma radiation is released after alpha or beta radiation when the nucleus has ____ ________ _____________

too much energy

What was initially observed in the energy spectrum of beta particles?

the energy of beta particles varied up to a maximum

What is the explanation for the energy spectrum of beta particles?

energy is carried away by neutrinos and antineutrinos

2 sources of neutrinos

1. nuclear reactor

2. sun