3.1 - Changes of State and Particle Model

Question 1

What is the definition of density?

Answer 1

● The mass per unit volume of a material

Question 2

State the different states of matter in
order (least to most) of density of atoms.

Answer 2

● Least dense: Gas
● Liquid
● Most dense: Solid

Question 3

Describe the particle arrangement of a
solid.

Answer 3

Tightly packed in a regular arrangement.
Particles can only vibrate on the spot.

Question 4

Describe the particle arrangement of a liquid.

Answer 4

Close together, but with an irregular
arrangement. They can flow over each
other

Question 5

Describe the particle arrangement of a
gas.

Answer 5

Separated, with no regular arrangement.
Particles can move freely.

Question 6

What is always conserved when a
substance undergoes a change of state?

Answer 6

mass

Question 7

How does a change of state differ from a
chemical change?

Answer 7

In a change of state, the material can
return to having its previous properties if
the change is reversed.

Question 8

What is sublimation?

Answer 8

When a solid changes into a gas without
passing through a liquid state.

Question 9

When water boils in an open pan, why
does the mass of the pan of water
appear to decrease?

Answer 9

Some of the water will evaporate and turn
into water vapour. This will leave the pan
meaning the mass of the pan will decrease.
The mass of the whole system however
remains constant.

Question 10

Explain the processes involved when a
bathroom mirror mists up.

Answer 10

● Hot water evaporates to form water vapour
● This water vapour lands on the cooler
mirror
● The vapour condenses and returns to liquid
state on the mirror’s surface