Atomic Structure Flashcards
(28 cards)
Who proposed the Plum Pudding Model, and describe its structure - Atomic Structure
JJ Thomson proposed the atom was a ball of positive charge with negative electrons spaced throughout
Who performed the Alpha Particle experiment and when? - Atomic Structure
Ernest Rutherford in 1905
What was the Gold + alpha particle experiment? - Atomic Structure
Alpha particles were fired at thin gold sheeting. It was thought they would pass straight through. Some did, but others were deflected.
What conclusions were made from the alpha particle experiment? - Atomic Structure
That the deflections must have come from a concentrated area of positive charge (the nucleus) and that ones that passed through were as a result of an atom being made up of mostly empty space
How did Niels Bohr believe electrons were placed in Rutherford’s model? - Atomic Structure
He believed that electrons orbited the nucleus at different distances or energy levels.
How do energy levels change? - Atomic Structure
When atoms absorb energy (from EM waves), electrons can move up energy levels, moving further from the nucleus. Vice-Versa for emitting energy.
What is an ion? - Atomic Structure
An atom with different numbers of protons to electrons
What are isotopes? - Atomic Structure
Isotopes are forms of elements that have the same number of protons but different numbers of neutrons
How can an atom’s nucleus be unstable? - Atomic Structure
If a nucleus contains dangerously more neutrons than protons, the nucleus can become unstable
What is an alpha particle? - Atomic Structure
A Helium-4 nucleus
What is a beta particle? - Atomic Structure
A fast moving electron
What is gamma radiation and how does it work? - Atomic Structure
A substance may emit a gamma wave in order to drop to lower energy levels
Which type of radiation is the most ionising? - Atomic Structure
Alpha - most easily converts from neutral into a charged particle
What is the definition of half life? - Atomic Structure
The time taken for half a radioactive substance’s unstable nuclei to decay.
Does a substance’s radioactivity theoretically ever reach 0? - Atomic Structure
No. The total of unstable nuclei just continues halving over the period of many half lives
What is irradiation? - Atomic Structure
Exposing objects to beams of radiation, allowing them to become irradiated.
Name 3 ways radiation can be positively used - Atomic Structure
Can be used to preserve fruit. Cobalt-60 kills bacteria on fruit when exposed, without damaging the fruit.
Can be used to destroy cancerous growths
Used to sterilise surgical instruments
How does irradiation of cancer cells work? - Atomic Structure
Beams of gamma are fired at a specific point from different angles. Healthy cells receive low doses of gamma, whilst cancerous cells receive high doses.
How can risks of dangerous irradiation be managed? - Atomic Structure
Keeping penetrative radioactive sources in lead lined boxes
Wearing protective clothing
Avoiding contact with skin
Monitor exposure using detectors
What is the unit for Radiation? - Atomic Structure
Becquerels (Bq)
Identify 4 causes of background radiation - Atomic Structure
Cosmic rays Food and drink Radon gas from the ground Nuclear power + weapons testing Medical sources Buildings + the ground
What do Sieverts measure? - Atomic Structure
Measures a dose of radiation and the damage that does would cause
Describe the process of nuclear fission - Atomic Structure
A neutron is fired at U-235. This causes the nucleus of the U-235 to split into 2 daughter nuclei + displacing neutrons. These neutrons impact other U-235 nuclei, releasing more energy. Chain reaction.
What slows neutrons down in a fission reactor so that they can be absorbed by fuel rods? - Atomic Structure
A graphite core
