Physics 5- The atom Flashcards
What does the Nucleus Contains
Protons / Neutrons
What charge is the nucleus
Positive
What comprises most of an atom
Empty space
The radius of the atoms nucleus is about 10,000 times smaller than the radius of what?
The atom
number of protons is equal to what?
number of electrons
atomic number defines what?
mass number defines what?
protons
When a nuclei decays, what 3 things will it split into?
What does this generally form?
Alpha
Beta
Gamma
A new element
When atoms gain/lose electrons, what does this form?
What are the 3 types of ionising radiation?
ions
a, b , g
Radiation from space is known as what?
Cosmic rays
What is the highest background radiation proportion?
Radon gas
Whats the lowest background radiation proportion coming from?
Nuclear industry
An alpha particle consists of how many neutrons/protons?
therefore what is its mass/charge?
2 protons / 2 neutrons
mass of 4
Charge of 2+
What are alpha particles good at (property)? why?
strong ionising
slow/heavy and bash into other atoms and creates ions
how far can alpha particles travel?
few cm in air
B particles are what?
name 2 properties from them that make them moderately ionising
electrons
fast / small
whats the mass and charge of b-particles
0 mass
-1 charge
Gamma rays are just what?
What does this mean for ionising?
EM waves
weak ionising - pass straight through atoms
What material stops alpha?
what material stops beta
what material stops gamma
paper
aluminium
lead
For every B-particle emitted from an element, what happens?
A neutron turns into a proton
atomic number increases with same mass number
what happens when alpha + beta enter a magnetic/electric field?
both are deflected in opposite directions due to their charge
which feels a greater force when entering a magnetic field… alpha or beta and why
Alpha as it has a greater mass
What happens to GM when they enter an electric field
Nothing as they have no mass/charge
Radiation dose is measured in?
sieverts (SV)
underground rocks can release what?
Radon gas
Why does high altitude (pilots) have increased chance of getting cancer?
Cosmic ray exposure
Half life is what?
average time it takes for the number of unstable nuclei in a radioactive isotope sample to halve
With half life equations, whats the first step to do?
Remove background radiation from the readings
Whats the 2nd step in half life equations?
take intial count and keep dividing by 2 until you reach the figure you need
whats the 3rd step in half life equations
divide the time (been given) by the amount of half lives you have calculated from 2nd step
in smoke detectors, what type of radiation is present?
What does this mean for smoke + Alarm
alpha radiation
alpha causes ionisation = current
Smoke absorbs radiation = no current = alarm
Name a type of radiation used as a tracer in medicine
iodine 131
What type of radiation are used for anything involving the body? whats its half life need to be?
Why?
beta / gamma. short half life so disappears quickly
they can pass out of the body
B-radiation can be used for what in industry?
Thickness gauges
passes through paper = if detector changes different level of radiation passing through, its too thick/too thin
When uranium decays (Half life) what does it decay into?
uranium + lead
Outside the body, what type of radiation is the most dangerous? why?
beta / gamma
can penetrate the skin –>organs
Inside the body, what type of radiation is the most dangerous?
alpha is it is strong ionising and cant escape
Whats used as protection when handling radiation?
lead as it absorbs all 3 type of radiation
In nuclear power stations, what atoms split into to form?
What “fuel” are used?
heat –>steam from water –> steam turbine
Uranium 235 / plutonium 239
for nuclear fission to work in a power station, what must starts the process? What does this lead to?
neutron is fired at the uranium 235 /plutonium 239
“fuel” becomes unstable–>breaks down into Barium + Krypton (Smaller nuclei) + 2 neutrons
What can happen with the 2 neutrons released from the breakdown of the “fuel”?
What stops this?
chain reaction causing overheating due to too much fuel being broken down
Control rods absorb neutrons
How can control rods stop meltdowns?
raised/lowered further into reaction to absorb more/less neutrons
this leads to less/more chain reactions from occuring
How does nuclear fusion differ from fission?
What does it involve?
formation of He + energy
2H+ coming together at high temperature/pressure
