Chapter 2: The nature of matter

Question 1

Why do we get three different states of matter?

Answer 1

Because of the different forces of attraction. When atoms overcome forces they can then change state. These forces affect the melting and boiling point of a substance.

Question 2

What does a pure substances melting and boiling point depend on?

Answer 2

The atmospheric pressure and forces between the substance .

Question 3

What is sublimation and give two examples?

Answer 3

When a substance goes straight from the solid state to the gaseous state skipping the liquid state.
Eg. dry ice and solid iodine.

Question 4

What is deposition and give an example?

Answer 4

When a substance goes straight from the gas state to the solid state skipping the liquid state.
Eg. frost on cold mornings

Question 5

What does the kinetic model of matter state?

Answer 5

That matter consists of a large number of small particles that are in a continuous random movement. The nature and amount of motion differs in solids, liquids and gases.

Question 6

What happens to the temperature of a substance while a change of state is taking place?

Answer 6

energy is being absorbed and given out and so the temperature stays constant during the phases of changing state.

Question 7

How can you indicate the degree of purity of a substance?

Answer 7

By the sharpness of its melting and boiling points.

Question 8

What are some methods that you can use to purify a substance from a mixture?

Answer 8

filtration, distillation, and chromatography

Question 9

What is a mixture?

Answer 9

It’s a combination of 2 or more types of atoms so no chemical bonds.

Question 10

What is the importance of purity?

Answer 10

• quality control for medicines
• quality control for raw materials
• confirm composition of finish products

Question 11

Define volatile:

Answer 11

Something that evaporates easily and has a relatively low boiling point.

Question 12

Define viscosity:

Answer 12

the resistance to flow

Question 13

What is filtration?

Answer 13

a physical technique to separate solids from fluids by adding a medium through which only fluids can pass.

Question 14

What does it mean if a substance is insoluble?

Answer 14

it doesn’t dissolve

Question 15

How does the words solution, solute and solvent relate to each other?

Answer 15

A solution is a mixture of a solute (the dissolved substance) and the solvent (the substance that the solute dissolves in)

Question 16

What does it mean if a solution is saturated?

Answer 16

It means that the solute can’t dissolve in the substance any more.
Solution only contains single bonds.

Question 17

What is crystallization?

Answer 17

When you take a solution and evaporate it and leave behind the solute as crystals.

Question 18

What is an element?

Answer 18

a substance that can’t be chemically broken down into simpler substances.

Question 19

What is a compound?

Answer 19

A pure substance made from two or more elements chemically combined together. The properties of compounds differ from the elements that they are made of.

Question 20

What are atoms?

Answer 20

They are the basic building blocks of life that cannot be changed but just reshuffled in chemical reactions.
They combine in fixed ratios to form elements and molecules.

Question 21

What is a molecule?

Answer 21

Atoms of different elements combine to make molecules of a compound.

Question 22

What is the subatomic particles of an atom and what are their relative charges?

Answer 22

Electron- negative electrical charge (-1) and hardly any mass.
Proton- one positive charge (+1) and a mass of one unit.
Neutron- no electrical charge (0) and a mass of one unit.

Question 23

What is the structure of the subatomic particles of an atom?

Answer 23

The protons and neutrons are bound together in the nucleus and make up most of the mass.
The electrons ‘orbit’ the nucleus in different energy levels or shells.

Question 24

What is an isotope?

Answer 24

atoms of the same element which have the same proton number but a different nucleon number

Question 25

What is the atomic number of an element?

Answer 25

The number of protons in that element and then in turn the number of electrons in that element.

Question 26

What is the mass number of an element?

Answer 26

it’s the total number of protons and neutrons in an atom.

Question 27

What is a radioisotope?

Answer 27

When there is an imbalance of neutrons and protons and in the nuclei that causes them to be unstable so the nuclei break up spontaneously, emitting radiation.

Question 28

What are some industrial uses of radioisotopes?

Answer 28

-isotope of uranium used in nuclear power stations
-monitoring of the levels of filling in containers
-checking the thickness of plastic, paper or metal foil during continuous production

Question 29

What are some medicinal uses of radioisotopes?

Answer 29

-cancer tumors can be killed using radioisotopes
- helps to sterilize medicinal instruments

Question 30

What is the maximum number of electrons in each energy level?

Answer 30

1st level: 2 electrons
2nd level: 8 electrons
3rd level: 8 electrons