3927108
Description
Flashcards by Helena Clarke, updated more than 1 year ago
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Created by Helena Clarke
over 8 years ago
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| Question | Answer |
| P2 T5 - Revision | P2 T5 - Revision |
| Describe what makes up an atom | protons - positive & mass of 1 neutrons - neutral & mass of 1 electrons - negative & mass is negligible |
| What is an ISOTOPE? | an atom that has the same number of protons but a different number of neutrons |
| ISOTOPE TRIVIA | every single element has isotopes: the first 82 elements have at least one stable isotope |
| Unstable Isotopes... | ... decay overtime and therefore, are radioactive |
| What are the three types of radiation? | Alpha, Beta and Gamma |
| Describe an alpha particle | helium nucleus, positive charge of +2, heaviest in mass, slowest in speed, most ionising b/c it is slow and has the biggest charge, worst at penetrating (stopped by paper, skin, 5cm of air) |
| Describe a beta particle | electron, negative charge of -1, very light mass, 2nd fastest, middle at ionising, stopped by few mm of aluminium |
| Describe a gamma ray | EM wave, no charge, no mass, fastest speed (speed of light), least ionising, best at penetration as only reduced by lead |
| Show the equation for the nuclear reaction for an ALPHA particle | X -> Y + X |
| Show the equation for a BETA particle | n -> p + e- |
| Is there an equation for GAMMA? | NO... b/c there is no change within the nucleus - it only loses energy |
| Describe nuclear fission | where one large nucleus splits up into two smaller nuclei plus some neutrons (between 1-4), releasing energy |
| Describe chain reaction | the neutrons given off then have a chance to hit more U-235 nuclei which would then follow the nuclear fission steps |
| what is the purpose of a moderator? | to slow the neutrons down because they are given off at incredibly fast speeds so it would bounce off the nuclei, therefore moderators slow down the neutrons in as little collisions as possible - commonly water + graphite |
| Describe what a control rod is and what they do | control rods control reactions in nuclear fission - lower them, and the reaction slows down; raise them, the reaction speeds up - commonly boron and they absorb neutrons in fission |
| What is nuclear fusion? | where two small nuclei join together to form one large nucleus, releasing energy; only happens when extremely high temperatures are speeding up each positive particle |
| What are the benefits of cold fusion? | does not give off any waste products so no environmental problems |
| what is cold fusion? | fusion at lower temperatures |
| why is cold fusion important? | because...: 1. solves energy problems overnight 2. huge amounts of hydrogen on Earth so supply would never run out 3. no waste products 4. incredibly environmentally friendly 5. virtually cost free |
| what happened in the 1980s that caused a big scandal around cold fusion? | two scientists claimed to have made cold fusion work BUT other scientists went to validate it but none of the experiments they did worked so could not be validated |
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