Chapter 6 -Radioactivity Flashcards
What was the first atomic model suggested? Who? When?
The Billard Ball model suggested by John Dalton in 1805. He stated different atoms ade up different elements but claimed that atoms could not be broken down which today we know is incorrect
Who suggested the atomic plum pudding model? When? What is it?
Thomson suggested this model in 1904 as he found electrons which were negative and knew the whole charge must be neutral so suggested that electrons were stuck to a positive mass
What was Ernest Rutherfords experiment and results
He used particles, a beam of alpha particles, to test the plum pudding model. He aimed these particles at a thin layer of gold foil and detected there passage through the foil. If the plum pudding model was correct then the particles should have all travelled through the foil straight, however some were repelled and came out of the foil at an angle. This Rutherford found was due to a small concentration of positive charge in the atom. This meant he made a new model with a central positive mass and orbiting electrons (meaning there is an empty space for the beams to go straight through).
What do we know today Rutherford didn’t?
Atoms also have neutrons
What is an isotope?
A vary of the same element (proton number) but with a different amount of neutrons and therefore mass
What is background radiation?
Radiation (NOT gamma, infra red, EM spectrum) is from where particles/ atoms have decayed, such as in stars fusion, nuclear activity, medical/industrial uses
What measures background/ ionising radiation? It’s activity?
A Geiger counter
What does the “activity” of radiation mean?
The number of decays a second
What is radioactivity described as? What is it measured in?
It is random. Measured in Bq, becqual
How does a Geiger counter work?
Ionising radiation enters an argon (conducting gas) in the Geiger counter through a mica window. Inside it collides with some atoms and smashes of some of their electrons (as it is ionising) which are attracted to the Sentra, anode (positive electrode) the rest of the atom is attracted to the cathode (negative electrode) causing electricity to flow and the circuit to be complete (momentarily) causing a beep to occur. The amount of beeps occurring is measured by the Geiger counter
What is the main source of background radiation?
Radon gas emitted from rocks, it is an alpha radiation.
What are the 3 types of radiation?
Alpha, beta, and positron (therefore gamma)
How can we detect radiation? Hint: not a Geiger counter but something else for on the move
By using a background radiation badge
Give examples for what we use radiation for?
Smoke alarms (ionising radiation), medical and industrial tracers, sterilising food (irradiation) or medical equipment, thickness control mill (foil, paper, plastics), treatment of cancer (radiotherapy)
Give an example of an industrial tracer
Finding leaks, blockages or cracks in pipes, you go over where the pipe is and look for either a decrease or increase in radiation, using a Geiger counter
