P6-particle model of matter 🧈🪶

Question 1

What are the three common states of matter ?

Answer 1

• solids, liquids and gases.

Question 2

Referring to particle theory, what can you tell me about the properties of solids ?

Answer 2

• solids are extremely hard to compress [squeeze]. This is because the particles in a solid are packed together [in a regular lattice arrangement].
• ; solids have almost no spaces between solid particles because, there are strong forces of attraction between the particles, which holds them close together, in fixed positions

Question 3

Why do solids have a fixed shape ?

Hint: can’t move from

Answer 3

• solids have a fixed shape and can’t flow from place to place.
• ; solid particles can vibrate in fixed positions [meaning around a fixed point] but cannot move from place to place.

Question 4

What are the properties of liquids ?

Hint: weak

Answer 4

• ; [unlike solids], liquids can take the shape of their container and they flow from place to place- this is because the particles in a liquid can move, due to a weak forces of attraction between the particles.
• They’re randomly arranged, and are free to move past each other [as they can change places], but tend to be/stick closely together.

Question 5

Why are liquids extremely hard to compress ?

Hint: spaces

Answer 5

• liquids are extremely hard to compress because, liquid particles are close together with not many spaces between them.

Question 6

Why are gases extremely easy to compress ?

Answer 6

• gases are [extremely] easy to compress because the particles in gases are widely spaced.
• this is because, the forces of attraction between the particles are very weak, meaning they’re free to move far apart. [are there are large gaps between gas particles], as gases move at constant random motion

Question 7

• Fill in the gaps: gas particles are ________ arranged, and are free to move past each other; they tend to be _____ together.

Answer 7

• gas particles are randomly arranged, and are free to move past each other; they tend to be close together.

Question 8

What is density ?

Answer 8

• density, is the mass per unit volume of a material [density tells us the mass for a given volume.]
• For example, a brick has a high density since it has lots of mass packed into its volume.
• ; a polystyrene block has a low density, and has a lower mass packed into its volume.

Question 9

What density do solids have ? Explain your answer

Answer 9

• solids have a very high density.
• This is because the particles are packed closely together, therefore solids have a lot of mass for their volume.

Question 10

What density do liquids have ? Explain your answer

Hint: mass

Answer 10

• liquids have a very high density.
• This is because the particles are close together, therefore liquids have a lot of mass for their volume.

Question 11

What density do gases have ? Explain your answer

Hint: small

Answer 11

• gases have a low density.
• This is because the particles are very far apart, so gases only have a small mass for their volume.

Question 12

What are exceptions to how the density of an object, relates to its particle arrangement ?

Hint: open structure

Answer 12

• polystyrene is a solid; it has a low density.
• This is because polystyrene has a very open structure, and is full of air spaces. It also has a small mass for its volume.

Question 12

Why do particles have potential energy ?

Hint: intermolecular

Answer 12

• particles have potential energy because, particles have intermolecular forces between them, and if the particle is a model, it will also contain chemical bonds.

Question 13

What is internal energy ?

Hint: make up a system

Answer 13

• internal energy is the energy stored in a system by the particles, and is the total kinetic and potential energy of all the particles [atoms and molecules] that make up a system.

Question 14

If we heat a solid, what happens to its internal energy ?

Answer 14

• if we heat a solid, we increase the internal energy and at some point the solid can melt, and turn into a liquid.

Question 15

What happens to the internal energy of a liquid, if we heat it ?

Answer 15

• if we heat a liquid, the internal energy increases and at some point the liquid will boil into a gas.

Question 16

A gas is cooled down, what happens to the internal energy of the gas ?

Answer 16

• if a gas is cooled down, the internal energy of the gas decreases and at some point, the gas will condense back into a liquid. [because the gas molecules slow down]

Question 17

A liquid is cooled. Can you tell me what would happen to its internal energy ?

Answer 17

• if a liquid is cooled, the internal energy of the liquid decreases [as it is cooled] and the liquid, will eventually freeze back into a solid.

Question 18

What is sublimation ?

Answer 18

• sublimation is when a solid can turn directly into a gas.

Question 19

What happens to mass, when a change of state takes places ?

Answer 19

• mass is always conserved, when changes of state takes place.
• since we’re not adding or taking away any particles.

Question 20

• Fill in the gaps: Changes of state are _______ changes, not ________ changes. If we reverse the change, the material recovers it’s _______ properties.

Answer 20

• Changes of state are physical changes, not chemical changes.
• If we reverse the change, the material recovers it’s original properties.

Question 21

What is evaporation ?

Hint: energy

Answer 21

• evaporation is when a liquid turns to a gas, but only on the surface of a liquid.
• this is because, only the particles on the surface have enough energy to turn into a gas.