Kinetic Theory And States Of Matter Flashcards
what are the three states of matter
- solid
- liquid
- gas
what do all the particles in each (pure) substance have in common
they are all the same type of particle
what is the difference between the particles in the three states of matter
the arrangement and energy of the the particles is different
what happens on a particulate level when you reverse a change of state
the particles go back to how they were before
what type of changes are changes of state and why
- physical changes
- because only the form of the substance changes
what is the difference between changing of states and chemical reactions
- during changes of state, the energy levels and arrangement of particles are different with no chemical change in the substance itself
- whereas in chemical reactions, new substances are created by the reaction
what are the particles like in a solid
strong forces of attraction hold the particles close together in a fixed and regular arrangement
how do particles move in a solid
- the particles dont have much energy in their kinetic energy stores
- so they can only vibrate about their fixed positions
what are the particles like in a liquid
- the forces of attraction between the particles are weaker than in solids
- the particles are close together, but can move past each other to form irregular arrangements
how do particles move in a liquid
- they have more energy in their kinetic energy stores than in solids
- so they move in random directions at low speeds
what are the particles like in a gas
there are almost no forces of attraction between the particles, meaning that there is no arrangement
how do particles move in a gas
- particles have more energy in their kinetic energy stores than in liquids and are free to move
- they travel in random directions at high speeds
what is the thermal energy store of a substance
the energy that is held in the kinetic energy stores of the particles that make it
what happens when you heat a liquid
- the extra energy is transferred to the kinetic energy stores of the particles
- making them move faster
when do liquids boil
- when enough of the particles have enough energy to overcome their attraction to each other
- and big bubbles of gas start to form in the liquid
what happens when you heat a solid and what is the process called
- the extra energy makes the particles vibrate faster
- until the forces between them are partly overcome (weakened) and the particles start to move around
- this is melting
in terms of volume, mass and density, which variables change when a substance changes shape
- the mass doesnt change
- the volume changes
- and therefore the density changes
why doesnt the mass of a substance that has changed state change
- because mass is the measure of the amount of atoms or particles making a substance
- and when the substance has changed state, there are still the same number of particles and atoms making it as the particles arent changing
- so the mass always remains the same
why does the density of a substance that has changed state from a solid to a liquid decrese
- particles in a solid are more tightly packed together than in a liquid
- when the substance changes shape to a liquid, the particles have more distance between them than they previously had (with weaker bonds and more kinetic energy)
- and as density is the measure of the number of particles in a given area (the compactness of an object), a lower number of particles in the same area in a liquid means it is less dense
- given that there are the same number of particles as before
how does the volume change when a substance changes state from a solid to a liquid
- the volume increases
- due to the reason that the density decreases (less particles in the same ares)
- and as volume = mass / density, a constant mass but a lower density means that the volume would be higher
