Topic 5 Flashcards
Which are the most energetic and the most dangerous waves
The ones with the highest frequencies (shortest wavelengths) are the most energetic
Dangers of gamma rays and X-rays
Can cause mutations (changes) to the dna in the cells in the body
Could kill cells or cause cancer
Dangers of ultraviolet
UV in sunlight can damage skin cells, causing sunburn
Overtime exposure to UV can cause skin cancer
UV can also damage the eyes leading to eye conditions
Infrared dangers
Infrared radiation transfers thermal energy. Too much infrared radiation can cause skin burns
Dangers of microwaves
Heat water
So they can the water inside our bodies
Heating cells can damage or kill them
Use of gamma rays
To sterilise good and medical equipment
In scanners to detect cancer
To treat cancer
Use of x rays
To look inside objects including medical x-rays to look inside bodies
In airport security scanners, to see what people have in their luggage
Use of ultraviolet
To detect security marks made using special pens
Inside fluorescent lamps
To detect forged banknotes
To disinfect water
Use of visible light
Allows us to see, lights up rooms and streets, building and roads
Photography
Use of infrared
In cooking (by girls and toasters)
To make thermal images (images using heat) used by police and rescue services
In short range communications such as between laptops or other small computers
In remote controls for TVs and other appliances where the signal only has to travel short distances
To send information along optical fibres
In security systems such as burglar alarms to detect pills moving around
Used of microwaves
In mobile phones, and to communicate by satellite transmissions
For cooking (in microwave ovens)
Used of radio waves
Broadcasting radio and TV programmes
Communicating with ships, aeroplanes and satellites
Radiation is absorbed or emitted when
Electrons jump between energy levels
Electrons can only exist in atoms at certain
Well defined energy levels
What do the energy levels in atoms depend on
Depend on the atom and the electrons inside the atom can move between the shells or leave the atom completely
Electromagnetic radiation is emitted or absorbed by atoms based on wether
Energy is given out of taken in
Electrons move up energy levels when they
Absorb energy and they fall down to lower energy levels when they emit energy
Electrons move from a lower energy to a higher energy level when
The correct amount of energy is absorbed
Electromagnetic radiation is emitted when electrons
Fall down from a higher to a lower energy level
Where can energy also be emitted from?
The nucleus of unstable atoms
What do protons and neutrons also occupy
Energy levels in the nucleus in the same way tht electrons do in the atom
When energy changes occur in the nucleus
High energy gamma rays are emitted
Gamma-rays can be emitted over a large range of frequencies depending on
The energy levels within the nucleus
Explain the energy changes that occur within the electron levels of the atom
Electrons can move between energy levels if they absorb or emit electromagnetic radiation
When they absorb electromagnetic radiation they move up energy levels and when they emit electromagnetic radiation they move down energy levels
The energy of electromagnetic radiation that is emitted or absorbed has to match the
Difference between the energy levels that the electron is moving between
Which energy changes are greater the ones in the nucleus or this seen between electron energy levels
In the nucleus
Atoms have a nucleus containing
Protons and neutrons
What move around the nucleus of the atom
Electrons
Protons =
Electrons
+ charged =
- charges so no overall charge
All atoms have a
Nucleus
What charge has a nucleus for
Positive because it contains protons which have a positive charge
And neutrons which don’t have a charge
The nucleus contains how much mass of the overall atom?
More than 99%
Total number of protons in an atoms nucleus must be the same as th
Total number of electrons in the shapes
Electrons in atoms always
Orbit the nucleus and have a negative charge
Atoms are always
Neutral because the pos cancels out the neg charge from the electrons
Nucleus of an atom of an Element my contain different numbers of
Neutrons
What’s a molecule
Two or more atoms bonded together
A molecule is about ___ times the diameter of an atom and about _____ times the diameter of a nucleus
10
10^6
Gases such as ________ are molecules
Oxygen and carbon dioxide
What is water
A molecule
Diameter of an atom is about
10^-10
Diameter of the nucleus is about
10^-15
All atoms of a particular element have the same number of
Protons
The number of protons in each atom of an element is called the
Atomic number or proton number
Protons and neutrons in an atom is the
Mass number of nucleon number
Atoms of a particular element always have the same number of protons but different numbers of
Neutrons
Atoms with the same number of protons but different number of neutrons are
Isotopes of the same element
What determines an element
Number of protons
What can electrons do
Move between energy levels, or they can leave the atom completely
An electron will move from a lower to a higher orbit if
It absorbs electromagnetic radiation
An electron will move from a higher to a lower orbit if it
Emits electromagnetic radiation
Electrons can leave an atom by:
Absorbing electromagnetic radiation of enough energy so that they can escape the pull of the nucleus
The three types of electromagnetic radiation that have enough energy to do that are UV, X rays and gamma rays
Being hit by a particle such as an alpha particle or beta particle
Alpha beta gamma and neutron radiation are emitted by
Unstable nuclei
What’s the process of nucleus decay
Tcompletely random so it’s not possible to determine exactly when
Some elements are radioactive because their
Nuclei are unstable
What does it mean having an unstable nuclei
They will undergo radioactive decay and change into other elements
Unstable nuclei will decay when
Alpha beta gamma or neutron radiation is emitted
An alpha particle is a
Helium nucleus
It is composed of two protons and two neutrons it has a charge of +2 and is the heaviest of the particles emitted by unstable atoms
What’s a beta particle
An electron
What charge does an electron have
-1
A positron is an
Anti-electron and has a charge of +1
A gamma ray is a form of
High-energy electromagnetic radiation. It has no mass or charge
Charge of a neutron
Zero
Alpha and beta particles and gamma-rays can collide with atoms which
Ionises then by causing them to lose electrons
Properties of radiation
Neutrons:
Not directly ionising
Have a very high penetrating power due to them having no charge and not interacting strongly with matter
Can travel through humans and building for long distances before being stopped
Alpha particles
Will travel around 5cm in air
Very ionising
Can be stopped by a sheet of paper
Beta particles
Will travel a few metres in air
Moderately ionising
Can be stopped by aluminium
3mm thick
Gamma rays
Will travel a few kilometres in air
Weakly ionising
Need thick lead to stop them
Low levels of radiation are present around you…
All the time
What’s background radiation
Both natural and man made
Background radiation is exposing us to
Ionising radiation
Background radiation is made up of many things such as
Ground and buildings
Medical
Nuclear power
Cosmic rays
Other
Food and drink
Random gas
What can be used to measure and detect radiation?
Photographic film and a Geiger-müller tube
What is the Geiger-müller tube
Is used to detect nuclear radiation
It is connected to a counter or rate meter which shows the amount of radiation that has been detected
Detecting radiation
In 1896 henri becquerel discovered that uranium sky’s would lead to the darkening of a photographic film even if it was wrapped up so that no light could reach it
Radiation was being emitted from the uranium nuclei and this was responsible for the darkening of the film this is now made use of in the nuclear industry as workers will wear a film badge to determine if they are being exposed to different forms of nuclear radiation
