Physics- Atomic structure Flashcards
1
Q
What is an isotope
A
An isotope is an element that has the same number of protons, but different number of neutrons.
2
Q
Alpha particle characteristics
A
- Are helium nuclei
- Has 2 neutrons and 2 protons
- Don’t penetrate far into materials + are stopped quickly
- can only travel few cm in air + are absorbed by a piece of paper
- Strongly ionising
3
Q
Beta particle characteristics
A
- A fast moving electron released by the nucleus
- 0 mass and charge of -1
- Penetrate moderately far into materials before colliding
- Range in air of few meter, absorbed by sheet of aluminium
- Moderately ionising
4
Q
Gamma ray characteristics
A
- Waves of electromagnetic radiation released by the nucleus
- Penetrate far into materials without being stopped
- Travel long distance through air and can be absorbed by thick lead or meters of concrete
- Weakly ionising, they pass through rather than collide with atoms
5
Q
What is a half life?
A
The time taken for the number of radioactive nuclei in an isotope to halve
6
Q
What are nuclear equations + how are they written
A
- They are a way of showing radioactive decay by using element symbols
- Written in the form: atom before decay—> atom after decay + radiation emitted
- Total mass and atomic numbers must be EQUAL on bother sides
7
Q
What does alpha decay do to the charge + mass of the nucleus
A
- Alpha decay DECREASES the charge + mass
- Atomic number reduces by 2
- Mass number reduces by 4
8
Q
What does beta decay do to the charge and mass of the nucleus?
A
- Beta decay INCREASES the charge but the mass STAYS THE SAME
- a neutron in the nucleus turns into a proton + releases a fast moving electron (the beta particle)
- Number of protons in the nucleus has increased by 1 - increasing the + charge (atomic number)
- lost electron and gained proton- mass doesn’t change.
9
Q
What do gamma rays do to the charge + mass of the nucleus?
A
- Gamma rays DON’T CHANGE the charge or mass
- way of getting rid of excess energy
- no change to atomic mass or atomic number
10
Q
What is background radiation?
A
- Background radiation is the low-level radiation that’s around us all the time
- You should always measure and subtract the background radiation from your results
11
Q
What are the sources of background radiation?
A
- Radiation from space- cosmic rays- from the sun. Earths atmosphere protects us.
- Radiation of naturally occurring unstable isotopes
- Radiation due to human activity
12
Q
What is irradiation?
A
- Something is irradiated when it’s been exposed to a radioactive source
- Irradiating something doesnt make it radioactive
13
Q
What is contamination?
A
- When unwanted radioactive atoms get onto or into an object
- Contaminating atoms might then decay, releasing radiation which could cause harm
- Wear protective gear and use tongs when handling sources
14
Q
What is the seriousness of each source outside the body?
A
- Beta and gamma most dangerous - both can penetrate the body and get to the delicate organs
- Alpha is less dangerous- can’t penetrate the skin- easily blocked by small gap of air
15
Q
What is the seriousness of each source inside the body?
A
- Alpha is most dangerous- highly ionising- do all damage in localised area
- Beta is less dangerous- moderately ionising- radiation absorbed over wider area
- Gamma lest dangerous- leat ionising- mostly pass straight out
