Chapter 1 - overview

Question 1

Define chemistry

Answer 1

Chemistry is a science that studies the composition, structure, properties and changes of matter. Also interested in energy involved in those changes

Question 2

define composition

Answer 2

composition is what matter is made up of

Question 3

define structure

Answer 3

structure is how matter is put together, what particles are attached to what particles and how they are attached.

Question 4

define property

Answer 4

a property is a characteristic/quality that matter has and can be used to identify a substance. eg density matter boiling and melting points

Question 5

define matter

Answer 5

matter can be defined as anything that has mass and occupies space

Question 6

define what a law is

Answer 6

a law is a statement of an observed regularity or pattern a rule that nature appears to follow

Question 7

what is the law of conservation of mass

Answer 7

chemists have found that the mass of chemicals before a reaction is the same as the mass of the chemicals after a reaction.

Question 8

define what a theory is

Answer 8

when scientists agree on an attempt to explain the law

Question 9

define the theory of matter (5)

Answer 9

1. All matter is made up of small particles (atoms,molecules or ions)
2. A pure substance has only one kind of matter present and one kind of particle - impure2 kinds of matter
3. Particles of matter have an attraction for each other
4. Particles are in constant motion
5. particles are not moving at the same speed

Question 10

what is a pure substance

Answer 10

element or compound that has only one kind of matter present.

Question 11

what is an impure substance

Answer 11

has 2 or more kinds of matter present. for example a mixture of sugar and water (2 kinds of particles sugar and water molecules)

Question 12

define a physical property

Answer 12

a physical property is a property that can be determined without changing the substance into a new substance

Question 13

what is the formula for density

Answer 13

density= mass of matter/volume of matter

Question 14

define chemical property

Answer 14

chemical property is a property that can only be determined when a substance is changed into another new substance. Eg carbon when reacts with oxygen creates carbon dioxide

Question 15

define a physical change

Answer 15

a physical change is a change in a substance without a new substance with new properties being produced. eg when ice melts it is still water

Question 16

define a chemical change

Answer 16

a chemical change is a change in a substance in which a new substance is produced having new physical and chemical changes (eg, rusting of a car)

Question 17

what is another name for a chemical change?

Answer 17

a chemical reaction

Question 18

what are the evidence for a chemical change? (7)

Answer 18

1. change in temp (heat given off/absorbed)
2. permanent change in colour
3. formation of a new odour
4. bubbles of gas produced in the liquid
5. a solid (precipitate) forms in the liquid after 2 liquids are mixed
6. a solid starting material gets used up
7. a new substance with new properties appears to form

Question 19

what is homogenous matter

Answer 19

matter that is uniform or constant of the same throughout. it has the same properties throughout. Elements compounds and solutions

Question 20

what is heterogeneous matter

Answer 20

matter that is not the same throughout. it is not constant or uniform throughout. The particles are not scattered evenly throughout. Eg tossed salad or a pizza