P1 - Matter Flashcards
What is the history of the atom?
DALTON - he proposed atoms were the smallest particle in the universe, that atoms were solid spheres and that they cannot be split.
JJ THOMSON- He made the plum pudding model (electrons distributed evenly throughout a ball of positive mass) and he discovered the negative electron.
RUTHERFORD: conducted the gold foil experiment to discover the nucleus where he shot positively charged alpha particles at a sheet of gold foil. Most of them went through however some deflected which allowed him to conclude there is a ball of positive mass at the centre of the atom (nucleus).
BOHR: he discovered that electrons orbit the nucleus at fixed shells and orbits.
The atom:
The atom is 1 x 10^-10 m wide (diameter)
Proton: Relative charge = +1 Relative mass = 1 Electron: Relative charge = -1 Relative mass = 0.0005 Neutron: Relative charge = 0 relative mass 1
What is the particle theory?
Solid (particles in a regular arrangement, close together and vibrate on the spot)
MELTING
Liquid ( particles close together, with definite volume but not shape, move around each other and in random arrangement)
EVAPORTATION
Gas (particles in random arrangement, move fast in all directions and are far apart from each other)
CONDENSATION
Liquids
FREEZING
Solids
When heating and there is a change in state, temperature stays the same as energy is absorbed to break bonds instead of raising temp.
When cooling and there is a change in state, temperature stays the same as energy is released to make new bonds instead of raising temp.
Relationship of density, mass and volume when changing state:
Density: Solids are denser than liquids which are denser than gases as particles are closer in solids.
Mass: Mass is always conserved when changing state.
Volume: Gases have more volume than liquids which have a larger volume than solids. Particles in gases are further apart than in solids.
Density (EQUATION + UNITS):
Density = mass / volume
Density = g/cm^3 Mass = g Volume = cm^3
How do you find density of irregular shaped object?
1) Measure mass of object using a scale
2) Fill measuring cylinder with a certain amount of water (eg 20cm^3)
3) Place in the object
4) The amount of water displaces (eg from 20cm^3 to 25^3) is the volume (in this case 5cm^3).
5) Use equation : Density = Mass / Volume to find density
What is the specific heat capacity?
The amount of energy to raise 1kg of a substance by 1 degree.
Energy transferred = mass x specific heat capacity x change in temperature
Energy = J
Mass = Kg
Change in temperature = c
Specific heat capacity = J/Kgc
What is the specific latent heat?
The amount of energy required to change the state of 1kg of a substance without raising temperature.
Energy transferred = mass x specific latent heat
Energy transferred = J
Mass = Kg
Specific latent heat = J/Kg
What is pressure?
Pressure is caused by particles hitting the walls of the container creating a force.
Each particles force on the container sums up and the force is expressed perpendicular to the surface.
The force acting per unit area on wall is pressure.
How does temperature affect pressure?
If temperature increases the particles gain energy in their kinetic energy stores making them move faster. The particles hit the walls of the container more often and with more force increasing pressure.
Increasing temperature, increases pressure.
Atmospheric pressure:
The lower you are on the Earth’s surface the more atmospheric pressure you feel as there are more particles above you.
The higher you are the less atmospheric pressure you feel as there are less particles above you.
Liquid pressure:
The lower you are in a liquid the more liquid pressure you feel as there are more liquid particles above you.
The higher you are in a liquid the less liquid pressure you feel as there are less liquid particles above you.
How does an object float or sink in terms of density and liquid pressure.
Density : For an object to float it has to be less dense than the liquid it is in. If it is denser than the liquid it is in it will sink.
Liquid pressure: Liquid pressure causes upthrust.
If upthrust = weight of object –> object floats
If upthrust > weight of object –> object floats
If upthrust < weight of object –> object sinks
Pressure equation:
Pressure(pa) = Force (N)/ Area (cm^2)
