Chapter 7: The Particulate Nature of Matter

Question 1

What does the Brownian motion prove?

Answer 1

It proves that particles are in constant random motion.

Question 2

How do infectious diseases get spread around the air?

Answer 2

When an infected person coughs, droplets containing water particles and virus particles are released into the air. The water droplets evaporates and the smaller virus particles left behind remain suspended in the air. These virus particles to not move in a straight path but move about randomly due to Brownian motion. This results in the virus spreading to other people nearby.

Question 3

What does a mask do when an infected person wears it?

Answer 3

The mask helps to prevent most of the virus particles from being dispersed in the air or landing on the nose or mouth of an uninfected.

Question 4

How are the particles in a solid arranged?

Answer 4

They are very closely packed together in an orderly manner.

Question 5

How do solid particles move around?

Answer 5

They vibrate about their fixed positions.

Question 6

The solid particles are held together by ___________

Answer 6

very strong forces of attraction

Question 7

How are the liquid particles arranged?

Answer 7

They are closely packed together in a disorderly manner.

Question 8

How do the liquid particles move about?

Answer 8

They move randomly and slide past one another.

Question 9

The liquid particles are held together by ___________

Answer 9

strong forces of attraction

Question 10

How are gas particles arranged?

Answer 10

The gas particles are far apart and are arranged in a disorderly manner

Question 11

How do the gas particles move?

Answer 11

They move randomly and quickly.

Question 12

The gas particles are held together by __________________

Answer 12

very weak forces of attraction.

Question 13

What happens when a substance in the solid state is heated?

Answer 13

When a substance in the solid state is heated, its particles gain energy and vibrate more vigorously about their fixed positions. The distance between the particles increase, causing the volume of the substance to increase as well. As a result, the substance expands.

Question 14

What happens when a substance in the solid state is cooled?

Answer 14

Its particles lose energy and vibrate less vigorously about their fixed positions. The distance between the particles decrease, causing the volume of the substance to decrease as well. As a result, the substance contracts

Question 15

What does not change during heating or cooling?

Answer 15

The size and number of particles in a substance.

Question 16

What happens during melting?

Answer 16

When a solid is heated, its particles gain energy. They vibrate faster about their fixed positions and eventually gain enough energy to overcome the very strong forces of attraction between them. The solid melts and become a liquid.

Question 17

What happens during boiling?

Answer 17

When a liquid is heated, its particles gain energy. They move faster and further apart from one another. They eventually gain enough energy to overcome the strong forces of attraction between them. The liquid boils and become a gas.

Question 18

What happens during freezing?

Answer 18

When a liquid is cooled, its particles lose energy and move slower. This causes the particles to be pulled much closer to one another by the forces of attraction between them. The particles are eventually held in fixed positions. The liquid freezes and becomes a solid.

Question 19

What happens during condensation?

Answer 19

When a gas is cooled, its particles lose energy and move slower. This causes the particles to be pulled closer together by the forces of attraction between them. The gas condenses and becomes a liquid.z

Question 20

Why does the heating curve remain constant during melting?

Answer 20

The temperature remains the same at 0 Celsius when ice melts into water because all the heat energy taken in is used to overcome the forces of attraction between the solid particles.

Question 21

Why does the heating curve remain constant when boiling?

Answer 21

Th temperature remains the same at 100 Celsius when water boils to form steam because all the heat energy taken in is used to overcome the forces of attraction between the liquid particles.

Question 22

What is the difference between evaporation and boiling?

Answer 22

1. Boiling takes place at a fixed temperature but evaporation can take place at any temperature.
2. Boiling takes place throughout the liquid but evaporation only takes place at the surface of the liquid.

Question 23

Define diffusion.

Answer 23

Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration. This is due to particles being in constant random motion.