state of matter Flashcards
How are particles represented in the particle mode?
by small solid spheres
In solids the particles…..
- have a regular arrangement
- are very close together
- vibrate about fixed positions
why are solids very close together in fixed positions to form a very regular lattice arrangement?
because there are strong forces of attraction between the particles
the hotter a solid becomes the more they_______
vibrate
the describe features of liquids
- have a random arrangement
- are close together
- flow around each other
Why do liquid particles flow around each other?
because there’s weak force of attraction between particles
liquid particles constantly move with what type of motion?
random motion
the hotter the liquid get the _______ it moves
What does this cause the liquid to do?
faster
this causes the liquid to expand slightly when heated
In gases the particles :
- have a random arrangement
- are much further apart
- move very quickly in all directions
why are gas particles much further apart?
because they have a very weak force of attraction
the hotter gas gets the ________ it moves
What does this cause the gas to do?
faster
gases either expand when heated or their pressure increases
What happens when a substance changes state?
- the particles themselves stay the same
- the way the particles are arranged changes
- the way the particles move changes
when does melting and freezing happen
at the melting point
when does boiling and condensing happen
at the boiling point
A pure substane will :
boiling and melting points
- melt and freeze at the melting point
- boil and condense at the boiling point
What does the amount of energy required for a substance to change depend on?
the amount of energy required to overcome the forces of attraction between the particles
the stronger the forces of attraction :
- the greater the amount of energy needed to overcome them
- the higher the melting point and boiling point will be
What are examples of substances that have high melting points due to strong bonds?
ionic compounds, metals and giant covalent structures
In substances that contain simple molecules:
- the bonds within the molecules are strong covalent bonds
- the forces of attraction between the molecules are much weaker
- only a little energy is needed to overcome the forces between the molecules, so the melting and boiling points are relatively low
What are the limitations of the particle model?
It doesn’t take into account:
- the forces between the particles
- the volume of the particles
- the space between particles
