9.5 Disintegration Processes Flashcards
What is an isotope?
form of an element with the same atomic/proton number but a different mass/nucleon number , due to different number of neutrons in nucleus
Do the chemical properties of isotope differ from the original element? Why
No, because the number of protons and electrons are conserved
Do the physical properties of an isotope differ from original element?
Yes, due to the different number of neutrons the density is different due to change in mass.
What must decay equations balance?
Charge(atomic number), nucleon number, energy and momentum (as well as lepton,baryon,strangeness number if applicable)
Do decay equations have to conserve mass? What is this process called?
No, this is a process of mass deficit
What is an alpha particle the same as?
A helium nucleus.
What does an alpha particle consist of?
2 protons and 2 neutrons
What element is a typical emitter of alpha radiation?
americium-241
What is the decay process of americium-241 ?
Am ——> Np + He
Where does alpha radiation usually happens?
In very heavy atoms, due to high mass it cannot be stable
What is the daughter element after a alpha particle is released in decay.
The original element’s mass number minus 4 units of mass/nucleon number. And original elements atomic number minus 2 units.
How can we represent graphically the decay process?
Mass number on y axis against atomic number on x axis. The original element is plotted and daughter element too, arrow goes pointing from original to daughter ..
What is the B- particle the same as?
an electron
What is a typical emitter of B- ionising radiation?
strontium-90
Example of stronium-90 decay process?
Sr——–> Y + B- + (anti)Ve
Why is there a electron antineutrino in the release of B- particle?
Since the lepton number then becomes plus 1 on the RHS compared to 0 on LHS. Hence we need to cancel the +1 without affecting the charge as it is already 0. So we add an electron antineutrino, which has no charge and lepton number of -1.
What happens when an element decays and releases B- radiation?
a neutron changes into a proton, electron and a electron antineutrino.
What happens during B- emission in terms of atomic and mass numbers?
The original element’s atomic/proton number receive 1 proton and mass/nucleon number stays constant.
When does B- emission usually happen?
In isotopes that are neutron rich (have many more neutrons than protons) when they decay.
Are isolated neutrons stable?
No they will decay
Why are B- particles released at random Ek, ranging from 0 to max.
Since during the decay process which causes the emission of B- particles, we also have 2 other particles (proton and electron antineutrino). This means that although they share momentum equally due to difference in mass they have very different energy. The neutrino thus takes the most energy.
What does the graph look like? Intensity of B- against Ek?
At 0 Ek the intensity is about 3/4 of y-axis, then it increases with Ek. Then starts to drop again until intensity is 0.
What is a B+ particle the same as?
A positron (anti electron)
Typical B+ emitter?
Potassium-38
