Topic 3 - Radioactivity and Ionising Radiation Flashcards
What is the relative mass of a neutron
1
What is the relative mass of an electron
1/2000
What is the relative charge of a proton
+1
What is the relative charge of a neutron
0
What is the relative charge of a electron
-1
What are the three types of radiation
Alpha
Beta
Gamma
What are the properties of alpha radiation?
Helium nucleus
Slow and heavy
Strongly ionising
Stopped by paper skin etc
What are the properties of beta radiation
An electron
Light and fast
Moderately ionising
Stopped by thin metal
What are the properties of gamma radiation?
Electronic radiation
No mass very fast
Weakly ionising
Stopped by thick lead or very thick concrete
What is a positron
A positron is the antiparticle of the electron. Same properties as electron except relative charge is +1.
What is annihilation?
When a positron and electron collide they are obliterated
What are the properties of neutron radiation?
Neutrons
More penetrating than alpha or beta and sometimes even more penetrating than gamma.
Not directly ionising but can be absorbed by the nuclei of atoms.
Emit ionising radiation - indirectly ionising
Absorbed by light nuclei
Absorption often makes nuclei emit gamma radiation
What makes a nucleus unstable
Too many/few neutrons
Too many protons and neutrons (too heavy)
Too much energy
What is the relative mass of a proton
1
what is an NZ graph
a graph that compares the number of protons and neutrons in an element.
What happens to elements above the curve of stability
too many neutrons B- decay
What happens to elements below the curve of stability
too few neutrons B+ decay
When does b- decay happen
when there are too many neutrons. It emits an electron from the nucleus and a neutron is changed into a proton.
What happens in b- decay
emission of electron from the nucleus. Neutron changes to proton the atomic number increases by one the mass number stays the same
when does b+ decay happen
when there are too few neutrons. Emits positron from the nucleus and proton gets changed to neutron.
what happens in b+ decay
emission of positron from nucleus
proton changes to neutron
atomic number decreases by one
mass stays the same
when does alpha decay happen
happens in heavy nuclei (more than 82 protons)
what happens in alpha decay
proton number increases by two nucleon number decreases by four
when does gamma radiation happen
happens when nuclei has too much energy often happens after b or a decay
what happens in gamma radiation
nuclei loses energy no change to atomic or mass number never just gamma emitted
What are quarks
smaller particles that make up protons and neutrons
What is the relative mass and charge of an up quark
mass: 1/3 charge: 2/3
What is the relative mass and charge of a down quark
mass: 1/3 charge: -1/3
What quarks make up a proton
up up down
what quarks make up a neutron
down down up
What happens in b- decay in terms of quarks
a down quark changes to an up quark
what happens in b+ decay in terms of quarks
an up quark changes to a down quark
what must be equal before and after radioactive decay
the charge
