Radioactivity Flashcards
What did John dalton think matter was made up of
Tiny spheres
Who discovered the plum pudding model
JJ Thompson
What experiment proved the plum pudding wrong
Alpha scattering experiment
What conclusions were made from the alpha scattering experiment
Most of the atom is empty space
The mass of the atom is concentrated in the centre
The nucleus has a positive charge
What is tha alpha scattering experiment
Scientist in Rutherford lab fires a beam of alpha particles at a thin gold foil
What were the predictions of the alpha particles experiment and what happened
Due to the plum pudding model it was expected that atom would pass through while most did some were deflected back and some were slightly deflected
Why did they conclude the nucleus was positive in the alpha particle experiment
Because the nucleus repelled the positive charge on the Gould sheet
Who proved the existence of neutrons
James. Chadwick
Describe the process of radioactive decay
Unstable isotopes decay into other elements and give out radiation as they try to become more stable they try to balance the number of protons and neutrons in the nucleus
What is alpha radiation
Find an alpha particle is emitted from the nucleus
Properties of an alpha particle
Alpha particles are consist of two neutrons and two protons they don’t penetrate very far into materials and Can be stopped quickly they can only travel a few centimetres in air and can be absorbed by a sheet of paper however they are strongly ionising
Properties of a beta particle
They have no mass and charge of minus one they are moderately ionising penetrate moderately far into materials and have range in air of a few metres
What is beta radiation
It is A fast-moving electron released by the nucleus for every beta particle emitted a neutron in the nucleus has turned into a proton
What are gamma rays
Waves of electromagnetic radiation released by the nucleus
Properties of gamma rays
Penetrate far into materials without being stopped and travel long distances three at the weekly ionising as they tend to pass through atoms rather than colliding with them they can be absorbed by six sheets of lads on metres of conch Street
What is the use of ionising radiation (alpha particles ) in smoke detectors not a threat to peoples house
4:30 do not travel far in air so they can be stopped by thin sheet of material therefore they cannot escape the smoke detector and harm people
If the atomic number of an isotope is Lower does that mean the charge is the same
No the charge will be lower as the number of protons in the nucleus is fewer
An unstable isotope is put inside a pipe which has a leak and radiation detectors moved along the path of a pipe explain how this method would help identify the leak
The unstable isotope for travel along the pipe add would be blocked by the pipe unless there is a leak therefore where there is a leak the radiation detector would have a higher current rate as the isotopes of radiation has escaped the pipe the radiation should be get a gamma rate as gamma rays are able to escape the pipe and reach the detector
What happens to an element when it goes through alpha decay
The atomic mass reduces by four and the atomic number reduces by two.
What happened to the element when it goes through beta decay
The atomic mass stays the same and the atomic number increases by one
What can radiation be measured with
A Geiger-Müller tube and counter
What is the count rate
The number of decays recorded each second
What is half life
The time taken for the number of radioactive nuclei in an isotope to halve
What can half life help to do
Find the rate at which a source decay and find its activity
What does radioactivity do over time
It decreases
Why can we not measure the activity
Because the activity never reaches zero
What is the term for exposure to radiation
Irradiation
How can we limit irradiation
By putting sources in lead lined boxes and standing behind a barrier when using the substance
Which radiation is the most dangerous outside your body and why
Beta and gamma sources because they can penetrate the body and get to delicate organs
What is the difference between contamination and irradiation
Irradiation is when an object is exposed to radiation however contamination is when unwanted radiation particles get onto objects
Should someone who is handling alpha particles be concerned about irradiation or contamination
Contamination as alpha particles cannot penetrate through skin so irradiation will not be a problem however if the other particles are ingested Or breathed in then they can be very dangerous as it can contaminate vital organs this is because they are strongly ionising
