Particle Model Of Matter Flashcards
Density is defined as
Mass/volume
Density - kg/m cubed
Mass - kg
Volume m cubed
What can the particle model be used to explain
The different states of matter
Differences in density
Solid
Tightly packed - ordered
High density
Particle Vibrates In fixed position
Definite shape
Incompressible
Particles have strong forces between them
Liquid
Particles - close together, random
Medium density
Moves and slides past each other
Definite volume, takes shape of container
Slightly compressible
Forces are weaker
Gas
Particles in a gas move freely at high speeds due to a very weak or no forces of attraction between them. Gasses have no fixed shape or volume and will expand to fit the shape of the container
Difference in densities
Density - measure of how tightly packed the particles are
Solid - solids are the mists dense state of matter
Liquids - less dense then solids - particles more spread out
Gasses - least dense - particles are far apart and move freely
Changes of state
Physical changes which differs from chemical changes because the material recovers its original properties if the change is reversed
One state to another - physical change. Mass doesn’t change it is conserved
Examples of changes of state
Solid - liquid - melting
Liquid to gas - evaporating
Gas to liquid - condensing
Liquid - solid - freezing
Solid - gas - sublimates
Internal energy
The term for the energy stored inside a system by the particles (atoms and molecules) that make up the system.
It is the total kinetic energy and potential energy of all the particles that make up a system.
How does heating change the energy stored within a system?
Heating changes the energy stored within a system by increasing the energy of the particles that make up the system. This either raises the temperature of the system of produces a change of state
What does the increase of temperature depend on?
The increase in temperature depends on the mass of the substance heated, the type of material and the energy input to the system.
What are the unfits for the change in thermal energy equation?
Change in TE - joules
Mass - kg
SHC - J/kg
Temp change - degrees
Latent heat
The energy needed for a substance to change state. When a change of state occurs, the energy supplied changes the energy stored but not the temperature.
Specific latent heat
The amount of energy required to change the state of one kg of the substance with no change in temperature.
What is the difference between specific latent heat of fusion and specific latent heat of vaporization
Fusion - changes of state from solid to liquid
Vaporization - Change of state from liquid to gas
SHC VS SLH
SHC - heat energy to raise temp of 1kg of substance by 1 degree Celsius without changing state
SLH - amount of heat energy needed to change state of 1kg WITHOUT changing temperature. - used for breaking or forming bonds during a state change. Temp doesn’t increase
Heating and cooling graphs
See on Goodnotes
Particle motion in gas
Molecules in a gas are at constant random motion. The temp of the gas is related to the average kinetic energy of the molecules.
Changing the temperature of the gas, held at a constant volume, changes the pressure exerted by the gas.
Temperature of gas
Temp rises so does speed of molecules. Temp is a measure of the average KE of the molecules in a substance.
If volume of gas constant and increase temp, the KE will increase - molecules move faster.
Pressure in gasses
Pressure is a result of collisions between the gas molecules and the container walls.
More molecules in a given volume - higher pressure. Gas molecules will collide more frequently with greater force. Pressure - Pa or atm.
Rekationship between gas and pressure
Heat gas - molecules gain KE - move higher speeds - more frequent and forceful collisions with container walls- increases pressure.
At a constant volume - increasing temperature will increase pressure.
What happens when a substance changes its state
The PE of molecules increase - overcome IM forces of attraction
KE remains same - temp will remain same even though substance being heated.
What is atmospheric pressure?
When the pressure stops decreasing significantly
