Particle Model Of Matter Flashcards
Solids
- strong forces of attraction hold the particles close together in a fixed, regular arrangement
- the particles don’t have much energy so they can only vibrate about their fixed positions
Liquids
- there are weaker forces of attraction between the particles
- the particles are close together but can move past each other and form irregular arrangements
- they have more energy than the particles in a solid, they move in random directions at low speeds
Gases
- there are almost no forces of attraction between the particles
- the particles have more energy than in liquids and solids
- they’re free to move and are constantly moving with random directions and speeds
What is the particle model of matter
That everything is made up of lots of tiny particles
What happens when gas particles collide
- they’re free to move around and as they move they bang into each other and whatever else happens to get in the way (like the sides of the container)
- when they collide with something, they exert a force on it
- pressure is the force exerted per unit area
- so in a sealed container, the outward gas pressure is the total force exerted by all of the particles in the gas on the unit area of the container walls
Wha happens wen you increase temperature of a gas
- increasing temp of gas transfers energy into the kinetic stores of its particles
- the higher the temp, the higher the average energy
- as temp is increased, the average peed of its particles increases
- this means that, for a gas at a constant volume, increasing its temperature increases its pressure
Why does faster speed of particles mean an increase of pressure
- as the particles are close together travelling quicker, it means that thy hit the sides of the container more often in a given amount of time
- each particle also has a larger momentum which means that they exert a larger force when they collide with the container
- these factors increase the total force exerted on a unit area and so increase the pressure
What is density
A measure of the ‘compactness’ of a substance. It relates the mass of a substance to how much space it takes up
What does density depend on
- depends on what it’s made of and how its particles are arranged
- a dense material has its particles packed tightly together
- the particles of a less dense material ae more spread out
- so density usually depends on different states of matter: solids are denser than liquids, liquids are denser than gases
How to find density of solid object
- Use blade to measure its mass
- If it a regular solid, measure its length width and height with a ruler and calculate the volume
- For an irregular solid, you can find its volume by submerging it in a eureka ca filled with water
- the water displaced by the object ill be transferred to the measuring cylinder - Record the volume of the water in the measuring cylinder. This is the volume of the object
- Use density formula to find density
How to find density of a liquid
- Place a measuring cylinder on a balance and zero the balance
- Pour 10 ml of the liquid into the measuring cylinder and record the liquids mass
- Pour another 10 ml into the measuring cylinder, resting the process until the cylinder is full and recording the total volume an mass each time
- For each measurement, use the formula to find the density
- Finally, take an average of your calculated densities. This will give you a value for the debit of the liquid
What is internal energy
- energy stored in a system is stored by it particles
- so, internal energy of a system is the total energy that its particles have in their kinetic and potential energy stores
What happens when you heat a system
- transfers energy t its particles (they gain energy in their kinetic and move faster) which increases the internal energy
- this leas to a change of temperature or a change in state
- if the temperature changes, the size of the change depends on the max of the substance, wha its made of and the energy input
- a change in state happens if the substance i heated enough, the particles will have enough energy input their kinetic energy stores to break the bonds holding them together
What does it mean that ‘mass is conserved’
- no particles are lost when it changes state
What are the flat spots of a temperature change graph
- where energy is being transferred by heating but not being used to change the temperature
What is latent heat
The energy needed to change the state of a substance
What happen when a substance is being melted or boiled
- energy is being put in and so increasing internal energy,
- but the temperature is used for breaking bonds rather than raising the temperature
- this is the flat part of a temperature change graph
What happens when a substance is condensed or frozen
- bonds are formed between the particles which releases energy
- this means internal energy decreases but the temperature doesn’t go down until all the substance has turned to liquid or a solid
- this is the flat par of a temperature change graph
What is specific latent heat
- the amount of energy needed to change 1 kg of a substance from one state to another without changing its temperature
What is the specific latent heat for cooling
- the energy released by a change in state of
What is the specific latent heat for changing between a solid to a liquid called
- called specific latent heat of fusion
What is the specific latent heat for changing between a liquid and a gas called
Specific latent heat of vaporisation
Formula for specific latent heat
Energy = mass x specific latent heat
