5) Atomic Physics Flashcards
Alpha particle:
A positively charged particle consisting of two protons and two neutrons. They are highly ionising, but can be stopped by a few centimetres of air.
Atom
The smallest component of an element having the chemical properties of the element, consisting of a nucleus containing combinations of neutrons and protons and one or more electrons bound to the nucleus by electrical attraction.
Electrons:
A negatively charged constituent of the atom, that are found in different energy levels, around the nucleus.
Isotopes
Atoms with the same number of protons but different numbers of neutrons. The atomic number is the same, but the nucleon number is different.
Nucleon number:
The number of protons and neutrons in an atom.
Nucleus
s a collection of particles called protons, which are positively charged, and neutrons, which are electrically neutral.
Nuclide notation:
Is a shorthand method of showing information about atoms.
Proton number:
The number of protons found in an atom of a specific element. Each element has a different proton number.
Background radiation:
The radiation that exists around us all the time
Beta particle
A high speed electron that a nucleus emits when a neutron converts into a proton. They are ionising but can be stopped by a thin sheet of aluminium.
Gamma ray
Electromagnetic radiation emitted from a nucleus. They have a very high penetrating power and require several centimetre of lead to absorb them.
Ionisation
The process in which an electron is given enough energy to break away from an atom.
Random nature of radioactive decay:
you cannot predict which nuclei in a radioactive sample will decay next, or when the next decay will occur - it is a random process.
Half life
the time taken for the nuclei of that isotope in any sample to decay
Ionising radiation:
Radiation that can cause cell mutations, damage cells and tissues, and lead to cancers.
What was rutherfords conclusion
1) Empty space
2) dense object
3) positive object
Why empty space?
Most particles passed straight through the metal foil without deflecting or bouncing back
Why dense object in the middle (nucleus)
Some bounced back at large angles impkying that they collided with a dense massive centre.
Why positive charge?
Some a particles deflected towards the source indicsting a strong replusive force
what is nuclear fission and fusion
nuclear reactants that change the nucleus of an atom to produce high amount of energy from the energy stored in the nucleus
Describe fission
Products move quickly and energy is transferred from the nucleus’s Nuclear eneergy to the nucleus KE.
The mass is less than the original because some mass is converted to wast energy.
(SPLITTING OF NUCELIS)
Why are isotopes like uranium and plutoniurm under go fission
Used in nuclear power stations
Describe nuclear fusion
Relase of energy by converting a small amount of mass into energy when two nuclei fuse. The fused nucleus has less mass than the original nuclei.
What does nuclear fusion require
Extermly high temperature and pressure that why its hard to reproduce in earth.
Natural sources of radiation?
1) rocks and buildings - Uranium in rocks decay into radon gas which is harmful if inhaled in large amounts.
2) NFood and drinks Radioactive elements like K - 40 are in food and water but not enough to harm you
3) Cosmic Rayts - Protons from the sun produce gamma radiation when they interact with the earths atmosphere.
Carbon dating
All living organisms contain carbon 14 which remains constant in their life and is used in radiocarbon dating,
how can you measure ionising nuclear radiation
usinga detector connected to the counter
describe the detector connected to the counter 5 marks
- detector uses count rate measure in s/min
- count rate is number of decays per second
- count rate decreases the further the detector is this is because radiation is more spread out and further away.
- Each time it absorbs radiation it send an electrical pulse to the counter causing a clicking sound and displaing the count rate on a screen
- higher count rate = more radiation aborbed
measuring background radiation
1) Remove all known sources of radioactivity from the room.
2) Set the counter to zero.
3) Switch on and start a stop clock.
4)After 20 minutes switch off. Record the count.
5) Divide the count by 20 to calculate the count rate per minute.
how to find corrected count rate?
1) measure bacjground without the source
2) measure count rate with the source
3) subtract both
why is instability common 3 marks
- large nucleus
- tooo many protons and or neutrons
- imbalance forces
Alpha Particles 3 marks
- Same as the heliums nucleus
- 2 protons and 2 neutons
- 2+
Beta particles 3 marks
- Fast moving electrons
- Produced in a nuclei when a neutron charges into a proton and an electron
- -1
Gamma particles 3 Marks
- Electromagnetic
- Highest energy
- No charge
What inc or dec down the table
range increases
penetrating power increases
ionisation decreases.
Alpha particles in magnetic and electric fields
Electic: Defelected downwards (negative side) because they are positively charged
magnetic: curve clockwise as they are positive
Beta particles in magnetic and electric fields
Electric: defelcted to the positive as they are negative
Magnetic: curve aniclockwise as they are negative
Gamma radiation in magnetic and electric fields
Electric: not deflected as they have no charge
Magnetic: not deflected as they are neutral
radioactive decay
where an unstable nucleus undergoes a change emitting alpha beta and gamma to make the atom stable. This occurs randomly
Istotopes of an element can be radioactive if and why do they become radioactive
- excess neutrons making the nucleus unstable
- nucleus is too heavy
they undergo radioactive decay to become more stable
Alpha decay
Reduces both atomic and mass numbers increases stability
Beta decay
Changes a neutron to proton increasing atomic number and improves stability but reduces excesss neutrons
Gamma emissions
Reduces energy without changing anything to reach stability.
Alpha notation
2/2 Helium
Beta notation
0/-1
gamma notation
0/0
If ypu have radium226 and it decays you will produce an alpha particle and the radioactive gas radon 222
226/88Ra = 222/86Rn + 4/2He
If you have carbon 14 and it decays you will produce a beta particle and nitrogen 14
14/6 c = 14/7n + b 0/-1
Why does half life matter
short half life = decay quickly
long half life = decay slowly
What are 5 ways half life is used in applicationb
1) smaoke detectors
2) Food steralization
3) Radiotherapy
4) Thickness control
5) Steralization
how does smoke detector use radiation
Alpha source of a long half life is used because it has highest ionisation effect.
why is food steralizatuon used in radiation
to kill bacteria in food which doesnt destroy vitamins.
Why is radiotherapy a use of radioactivity
Gamma is used to kill cancer cells.
why is thickness control a use of radioactivity
This measures how much radiation passes through the sheet.
- If too much radiation passes through the sheet is thin
- If too little the sheet is thick
The radiation used muct have a long half life
Why is steralization a use of radiotherapy
Ionization can kill living cells which can kill microorganismjs on surgical instruments .
how do you move radioactive materials
Sheild containers and warning labels
how do you use radioactive materials
protective gear and minimize exposure and controlled areas
How do you store radiactive materials
shielded strorange and clear labelling and safe location
Saefty precautions for ionising radiation
1) Reduce exposure time
2) Increase distance
3) sheilding
