5. Atomic Physics Flashcards
Describe the nucleus of a radioactive atom
Most atoms each have a stable nucleus that doesn’t change
Atoms of a radioactive substance each have a nucleus that is unstable
They becomes stable by emitting alpha, beta or gamma radiation
Describe alpha radiation
2 protons and 2 neutrons Charge: +2 Mass: 4 Ionizing: strong Penetration: not penetrating, stopped by paper
Describe beta radiation
1 high energy electron Charge: -1 Mass: 1/2000 Ionizing: moderate Penetrating, stopped by aluminium
Describe gamma radiation
It is electromagnetic wave -> electromagnetic radiation
Charge = 0
Mass = 0
Ionizing: weak
Very penetrating, only stopped by thick lead or concrete
What is ionization
Radiation from radioactive substances knocks electrons out of atoms and the atoms become charged
Describe alpha, beta and gamma deflection in electric fields
Gamma radiation is electrically neutral -> alpha and beta radiation can be deflected by the electric fields but gamma is not
Alpha particles are positively charged -> attract towards a negatively charged plate
Beta particles are negatively charged -> attract towards a positively charged plate
Describe background radiation
Ionising radiation that is constantly present in our natural surroundings
Some come from natural sources: air, ground, cosmic
Some come from artificial sources: medical, food&drink, air travel, nuclear weapons
Describe alpha, beta and gamma deflection in magnetic field
Beta radiation is easily deflected
Alpha radiation is deflected in the opposite direction to beta radiation bc they have opposite charges
Beta radiation is harder to deflect than alpha radiation bc it has much more mass -> more force to change its direction of motion
Gamma radiation is not deflected by a magnetic field
Compare the ionization of alpha, beta and gamma radiation and suggest reason
Alpha > beta
Bc alpha particle has much more mass than beta particle and moves more slowly -> has much more effect on the atoms it encounters
Beta > Gamma
Bc beta particles are charged whereas gamma radiation is uncharged
What is decay?
When an unstable nucleus emits radiation
Radioactive is a random event and cannot be predict or influence when it will happem
Describe the decay of alpha, beta and gamma
Alpha radiation is released in the form of a helium atom
Beta is releases in the form of an electron
Gamma radiation: energy is released
Define half life
The time taken for half the nuclei to decay
What are some safety precaution when using radioactive substances
Wear protective clothing - gloves, lab coat, safety glasses
Radioactive stuff is stored in a lead container, in s locked cabinet
Picked up with tongs
Kept away from body, not pointed at ppl
Left out of its container for as short a time as possible
Define isotope
Atoms of the same element with the same number of protons but with different number of neutrons
