Kinetic theory tells us that gases consist of very small particles, they are moving in random directions, collide with each other and with the walls and bounce off.
Absolute zero- When you increase the temperature of something, the particles gain energy so they move more quickly or vibrate.
Also when you decrease you reduce the energy
The coldest anything can get is -273C or 0K which is zero Kelvin
Celsius to Kelvin you add 273
Kelvin to Celsius you subtract 273
If you increase the temperature of a gas it gains more energy
The temperature of a gas (K) is proportional to the average kinetic energy of its particles
Kinetic theory and pressure in gases
When gases collide they exert a force on the thing, in a sealed container gas particles smash against the walls creating an outward pressure.
Pressure Depends on:
How fast particles are going
How often they hit the walls
Temperature and pressure are proportional, double the temp so you get double the pressure
Bigger container= less pressure because of fewer collisions
Pressure/Temperature (K)=Constant - for sealed containers
Pressure x Volume/ Temperature (K)= Constant P1 x V1/ T1= P2 X V2/ T2
Paticles in Atoms
Positron are opposite of electrons, have the same mass but opposite charges, they get annihilated when electron meets it.
Neutron- More penetrating then alpha and beta
not ionising but gets absorbed by the nuclei of an atom which makes a nucleus radioactive.They get absorbed by light nuclei best such as hydrogen so things such as water, polythene or concrete used to make neutron shielding. Also thick lead is used because gamma rays are emitted
They emit ionising radiation such as gamma, beta and alpha
Alpha Beta Gamma What is it Helium Nucleus Electron EM wave speed and weight Slow & Heavy Light & Fast No mass & Very fast Ionising Strongly Moderately Weakly Stopped by Paper, skin etc Thin metal Lead and thin concrete
Paticles in Atoms
Neutrons difficult to detect because of being neutral, so they are detected by nuclear decays from nuclei.
A isotope above the curve has too many neutrons to be stable
A isotope below the curve has too few neutrons to be stable
B- happens when there are too many neutrons then protons so a neutron is changed into a proton. Emits electron
B+ happens when there are less neutrons, so a proton gets changed into a neutron. Emits positron
Alpha happens in heavy nuclei such as uranium, radium etc so the nuclei are too massive to be stable. The proton number then decreases by 2 and nucleon by 4.
Gamma happens when Nuclei has too much energy, it happens after alpha or beta decay because the nucleus has excess energy so it loses energy by emitting gamma rays.
Fundamental and other particles
Electrons and Positrons are fundamental particles because you cant split them up into something smaller
You can make new fundamental particles by making 2 protons collide at a high speed, so the energy turns into mass and this makes matter and anti matter. So antimatter has antiparticles which can be fundamental particles.
Protons and neutrons are NOT fundamental particles because quarks make them.
Proton- 2ups and 1 down
Neutron- 2 downs 1 up Quarks- Up= 2/3 Down= -1/3
When Quarks change they turn into Electrons or Positron:
When neutron turns into proton electrons are produced to make it balanced so B- decay
When protons turn into neutron a positron is produced making it balanced so B+ decay
Electron guns (Cathode ray tubes) use Thermionic emission
The heater heats the cathode which gives energy to the electrons, then the electrons boil off (escape) this is called Thermionic emission
The electrons then accelerate as they're pulled towards the anode, it has a gap which channels the electrons into an electron beam
The electric field between the charged metal deflects the electron beam
The phosphorescent screen glows when electrons hit it
Kinetic energy of an electron (J)= Charge of electron (C) x Accelerating voltage (V)
Current(I)= Charge (n x e)/ time(t) n= charge on electron e= number of electrons
Electron charge= -1.6 x 10^-19 C C= Coulombs
Electron beam is deflected by an electric field:
It is attracted by a positive charge and repelled by a negative charge.
2 Pairs of charge metal plated are used to deflect the electron, one deflects it up and down which is the Y plates and the X plates move it left or right
Particles are deflected more by:
- Bigger charge on plates
- Bugger charge on particles
- Slower moving particles
- Lighter particles
Particles are less deflected by:
- Smaller charge on plates
- Smaller charge on particles
- Faster moving particles
- Heavier particles
Electron guns are used in TVs, Oscilloscopes and X-rays
Oscilloscope is something which displays the voltage and frequency of an electrical signal. Y axis = Voltage and X axis= Time
TV tubes, PC monitors and oscilloscope have an electron hitting a screen covered in phosphorescent chemicals, which these chemicals emit light
Electron beams produce X-rays by by having no deflecting plates or phosphorescent screen. They have a positively charged target, when electrons hit the target the Kinetic energy is converted to X-rays.
Particles Accelerators such as CERN, they smash up particles in extremely fast speed to see what happens, what is made from them etc. It gives clues how the universe was made and if theorys such as Hugson boson theory is correct. It cost billions of pounds so research is done internationally.