1.2 Basic ideas about atoms - Radioactivity Flashcards
Define Radioactivity
The spontaneous disintegration of the nucleus of an element
How is radioactivity different to chemical change?
The nucleus breaks apart without anything being done to the element in radiactivity
Define radiation.
The energy or particles emitted by an element when it disintegrates
Which elements are radiactive?
Elements with an atomic number greatr than 93
isotopes of some smaller atoms are also radioactive
When an unstable nucleus splits up (disintegrates) what can it produce?
emits radiation
a different atom with a different number of protons is formed
Define radioisotope
any isotope of an element which is radioactive
What are the three types of radiation?
Alpha, Beta and Gamma
What is alpha made from/ what is the nature of alpha?
What can it pass through?
What is it absorbed by?
Is it affected by elec/magnetic fields?
What is its ionising power?
What is its speed?
Made from helium nuclei
Passes through air
Absorbed by paper/skin
Yes it is affected by mag fields
Strong ionising power
Slowest radiation (10% of speed of light)
What is beta made from/ what is the nature of beta?
What can it pass through?
What is it absorbed by?
Is it affected by elec/magnetic fields?
What is its ionising power?
What is its speed?
Is a high speed electron
Passes through air/paper/skin
Absorbed by aluminium
Yes it is affected by mag fields
medium ionising power
medium radiation (50% of speed of light)
What is gamma made from/ what is the nature of gamma?
What can it pass through?
What is it absorbed by?
Is it affected by elec/magnetic fields?
What is its ionising power?
What is its speed?
is an electromagnetic wave
Passes through air/paper/skin/aluminium/iron
Absorbed by concrete (only reduced)
No it is not affected by mag fields
weak ionising power
fastest radiation (100% of speed of light)
How many neutrons does an alpha particle have?
2
How many protons does an alpha particle have?
2
When a nucleus emits an alpha particle, by how much does the atomic number of the remaining nucleus decrease?
2
When a nucleus emits an alpha particle, by how much does the mass number of the remaining nucleus decrease?
4
When an atomic number emits a beta particle, how much does the mass number of the remaining nucleus change by?
no change
What is the difference between positron decay and beta decay?
In Positron decay a positive charged beta particle is emitted and in Beta decay a negative charged beta particle is emitted
What happens in electron capture?
an electron from the closest energy level falls into the nucleus
what is the equation for electron capture?
element + negative charged electron -> new element + neutrino
What is the effect of electric and magentic fields on the three types of radiation?
Beta particles move faster to the North Pole (positive)
Gamma particles aren’t affected
Alpha particles move slower to the South Pole (negative)
Define ‘half-life’
the time taken for half the radioactive atoms in a sample of radioactive isotope to decay
What is the use of radiocarbon dating?
used to calculate the age of plant and animal remains as all living animals absorb carbon which includes a small proportion of radioactive carbon-14
What is the use of gamma radiation in the treatment of cancer?
the high energy of gamma radiation used to kill cancer cells and prevents a malignant tumour from developing
What is the use of tracers in for diagnosis and treatment in medicine?
to make soft tissues, such as blood vessels or the kidneys, show up through medical imaging processes
what are the uses of dating rocks?
Geologists commonly use radiometric dating methods, based on the natural radioactive decay of certain elements such as potassium and carbon, as reliable clocks to date ancient events
