T4 - Atomic structure Flashcards
Radius of atom?
1 × 10^-10m
Radius of nucleus?
1 x 10^-14m
Which electrons shell have higher energy?
electron shell further from nucleus
What happens to electron when atom absorbs electromagnetic radiation?
moves to high electron shell
What happens to electron when atom emits electromagnetic radiation?
moves to lower electron shell
What is an isotope?
Atoms of the same element that have different numbers of neutrons
What is radioactive decay?
when the nucleus gives out radiation to become more stable
Feature of radioactive decay?
its a random process
What is activity?
rate at which a source of unstable nuclei decay
What is activity measured in?
becquerel(Bq)
What is the count rate?
the number of decays recorded each second by a detector
Types of radiation? x4
-alpha particle
-beta particle
-gamma ray
-neutrom
What is an alpha particle?
two neutrons and two protons
which nucleus is the alpha particle same as?
helium nucleus
What is a beta particle?
a high speed electron ejected from the nucleus as a neutron turns into a proton
What is a gamma ray?
electromagnetic radiation from the nucleus
How far can alpha paricles travel?
5cm
How far can beta paricles travel?
15cm
How far can gamma rays travel?
several metres
What are alpha particles stopped by?
a sheet of paper
What are beta particles stopped by?
few millimetres of aluminium
What are gamma rays stopped by?
several centimetres of lead
Ionising power of alpha particles?
very strongly ionising
Ionising power of beta particles?
quite strongly ionising
Ionising power of gamma rays?
weakly ionising
What is ionising power?
when atoms loose electrons and form ions when collided with radiation
What happens to atomic number during alpha decay?
decreases by 2
What happens to the mass number during alpha decay?
decreases by 4
What happens to atomic number during beta decay?
increases by 1
What happens to mass number during beta decay?
stays the same
What happens to the mass and atomic number during gamma decay?
stays the same
What is half life?
time it takes for the number of nuclei of the isotope or count rate in a sample to halve
What is irradiation?
exposing an object to nuclear radiation
What happens to the object getting irradiated?
it doesn’t become radioactive
Why doesn’t an object getting irradiated become radioactive?
doesnt come in contact with radioactive isotope
Why is ionising radiation dangerous?
increase risk of cancer
What are the precautions that can be taken to when working with radioactive isotopes? x2
- shielding
-monotoring
How to take precaution of alpha radiation by shielding?
gloves
How to take precaution of beta and gamma radiation by shielding?
lead apron
What is radioactive contamination?
when unwanted radioactive isotopes end up on other materials
Why are affect of radiation on humans published and shared with other scientists?
so it can be peer reviewed
where does natural background radiation come from? x2
-rocks
-cosmic rays
where does man made background radiation come from? x2
-nuclear weapon testing
-nuclear accidents
What can affect your exposure to background radiation? x2
-occupation
-location
Uses of nuclear radiation in medicine? x2
-exploring internal organs
-control or destroy unwanted tissue
How can nuclear radiation help explore internal organs- thyroid gland?
radioactive iodine drank to see condition of thyroid gland
How can nuclear radiation help explore internal organs-tumours?
tracers
Issues of tracers? x4
-radiation must pass out of body
-not strongly ionising
-not decay into radioactive isotope
-must have short half life
How can nuclear radiation destroy unwanted tissue? x2
-radiotherapy
-radioactive rods
Issues of radiotherapy?
healthy tissue can be destroyed
What is nuclear fission?
splitting of large and unstable nucleus
What must happen to unstable nucleus for fission to occur?
absorb neutron
process of nuclear fission? x3
- unstable nucleus absorb neutron
- nucleus splits to 2
- emits 2 or 3 neutrons and gamma rays
What is released by fission?
energy
what do all fission products have?
kinetic energy
What is a chain reaction?
repetition of nuclear fission
What is a chain reaction is controlled in?
nuclear reactor
Why is chain reaction controlled in a nuclear reactor?
to control energy released
what is a nuclear weapon explosion caused by?
uncontrolled chain reaction
What is nuclear fussion?
joining of two light nuclei to form a heavier nucleus
What happens to some of the mass of nuclei during nuclear fusion?
converted into energy of radiation