1.2 Classifications of Matter

Question 1

How is matter typically characterised?

Answer 1

Matter is typically characterised by its physical state (gas, liquid or solid) and its composition (element, compound or mixture)

Question 2

What are the 3 states of matter?

Answer 2

Solid, liquid and gas

Question 3

Solid?

Answer 3

Matter that has both a definite shape and a definite volume, Not compressible to any appreciable extent

Question 4

Liquid?

Answer 4

Matter that has a distinct volume independent of its container, assumes the shape of the portion of the container it occupies, is is not compressible to any appreciable extent

Question 5

Gas?

Answer 5

Matter that has no fixed volume or shape; it uniformly fills its container

Question 6

Explain the properties of a gas on a molecular level

Answer 6

In a gas, the molecules are far apart and moving at high speeds, colliding repeatedly with each other and with the walls of the container.

Question 7

Explain what occurs on a molecular level when a gas is compressed?

Answer 7

Compressing a gas decreases the amount of space between molecules and increases the frequency of collisions between molecules. But the shape and size of the molecules DON’T change.

Question 8

Explain the properties of a liquid on a molecular level.

Answer 8

In a liquid, the molecules are packed closely together, but still move rapidly. The rapid movement allows the molecules to slide over each other, thus a liquid pours easily.

Question 9

Explain the properties of a solid on a molecular level,

Answer 9

In a solid, the molecules are held tightly together, usually in definite arrangements in which molecules can wiggle only slightly in their otherwise fixed positions.

Question 10

Discuss the main differences between solids and liquids on a molecular level.

Answer 10

The distances between molecules are similar in the liquid and solid states, but in solids the molecules are for the most part locked in place, in liquids they retain considerable freedom of motion.

Question 11

What can lead to conversion from one state to another?

Answer 11

Changes in temperature and/or pressure

Question 12

Pure substance?

Answer 12

A pure substance is matter that has distinct properties and a composition that does not vary from sample to sample.

Question 13

Elements?

Answer 13

Elements are substances that cannot be decomposed into simpler substances. On the molecular level, each element is composed of only 1 kind of atom.

Question 14

What are examples of pure substances?

Answer 14

Water, Table salt

Question 15

Compounds?

Answer 15

Compounds are substances composed of 2 or more elements. They contain 2 or more kinds of atoms.

Question 16

Example of a compound?

Answer 16

Water - H2O

Question 17

Mixtures?

Answer 17

Mixtures are combinations of 2 or more substances in which each substance retains its chemical identity.

Question 18

Law of constant composition / Law of definite proportions

Answer 18

A law that states that the elemental composition of a substance is always the same. Regardless of its source (nature or laboratory), a pure compound has the same composition and properties under the same conditions.

Question 19

Difference between pure substance and mixture?

Answer 19

A pure substance has a fixed composition whereas the composition of a mixture can vary.

Question 20

Heterogeneous mixtures?

Answer 20

Mixtures which don’t have the same composition, properties and appearance throughout

Question 21

Homogenous mixtures?

Answer 21

Mixtures which have a uniform composition throughout.

Question 22

Examples of heterogeneous mixtures?

Answer 22

Rocks, Wood

Question 23

Examples of homogenous mixtures?

Answer 23

Air, when salt or sugar are dissolved in water

Question 24

Another word for homogenous mixtures?

Answer 24

Solutions

Question 25

Solution?

Answer 25

A mixture of substances that has a uniform composition, a homogenous mixture