Topic Three - Particle Model Of Matter Flashcards
How is the particle model used?
To describe how particles behanve in three states of matter: solid, liquid and gas.
How are solids arranged?
Strong forces of attraction hold the particles close together ina fixed, regular arrangement.
The particles dont have much energy so they can only vibrate in their fixed positions.
The density is genrslly the highest in this state as the particles are closest together.
How are liquids arranged?
There are weaker forces of attraction between the particles.
The particles are still close together but can move past each other and form irregular arrangments.
For any substance in the liquid state it will have more energy than in the solid state.
They move in random directions at low speeds.
Less dense than solids.
How are gases arranged?
Almost no forces of attraction between the particles.
For any given substance in the gas state its particles will have more energy than in the solid or liquid state.
They are free to move and travel in random directions at high speeds.
Gases have low densities.
What is density?
The measure of the compactness of a substance.
What does the density of an object depend on?
A dense material has particles packed tightly together. The particles in a less dense material are spread out. So density depends on the states of matter.
Density practical- how do you find the density of a solid object?
Use a balance to measure its mass.
For some solid shapes you can find the volume by using its formula (cube= width x height x length)
For different shapes you can find the volume by sumberging it in a eureka can filled with water. The water displaced by the object will be transferred to the measuring cylinder.
Record the volume of water in the measuring cylinder. This is the volume of the object.
Put the mass and volume into the formula to find the density.
Density practical - how would you find the density of a liquid?
Place a measuring cylinder on a balance and zero the balance.
Pour 10ml of liquid into the measuring cylinder and record the liquids mass.
Pour another 10ml into the measuring cylinder and record the total volume and mass. Repeat this until the measuring cylinder is full.
For each measurement use the formula to find the density (1ml = 1cm cubed)
Take an average of the calculated densities to get an accurate value of the the density of the liquid.
What is internal energy?
The total energy that its particles have in their kinetic and potential energy stores.
What does heating do to the internal energy?
They gain kinetic energy and move faster so internal energy increases.
This leads to a change in temperature or change of state.
The size of the temperature change depends on the mass, what it is made of and the energy input.
A chane in state would occur if the substance was heated enough. The particles will have enough energy in the kinetic energy stors to break the bonds holding them together.
What happens when you heat a liquid?
It evaporates into a gas.
What happens when you heat a solid?
It melts to become a liquid.
What happens when you condense a gas?
It turns to liquid.
What happens when you freeze a liquid?
Turns solid.
What happens when you change the state of a substance?
You have the same substance as you started with just in a different form. The number of particles doesnt change they are just arranged differently meaning the mass is conserved.
