Elements, mixtures and compounds

Question 1

What is an element?

Answer 1

an element is a pure substance that cannot be broken down into a simpler substance. An element is made out of one type of atom only

Question 2

What state are elements?

Answer 2

They can be solids, liquids or gases

Question 3

What is a compound?

Answer 3

Most substances are not elements because they are not made up from one type of atom only. A compound is made from atoms of at least two different elements joined together by a chemical bond.

Question 4

What is a mixture?

Answer 4

these are different substances mixed together but not joined by chemical bonds; there is no link between them. The parts of a mixture can be elements or compounds or both, it makes little difference and the mixture can have any composition.

Question 5

What is a chemical formula?

Answer 5

a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule

Question 6

What is the composition of a compound?

Answer 6

it has a fixed composition that can’t change

Question 7

Does mixing substances change their properties?

Answer 7

No

Question 8

What is the appearance of iron?

Answer 8

silver/grey solid

Question 9

What is the appearance of sulphur?

Answer 9

yellow solid

Question 10

What is iron’s density compared to water?

Answer 10

it’s more dense (it sinks in water)

Question 11

What is sulphur’s density compared to water?

Answer 11

sulphur powder floats

Question 12

What is the effect of a magnet on iron?

Answer 12

iron is attracted to a magnet as it is magnetic

Question 13

What is the effect of a magnet on sulphur?

Answer 13

it has no effect as sulphur is not magnetic

Question 14

What is the effect of dilute hydrochloric acid on iron?

Answer 14

it reacts with iron and gives off hydrogen

Question 15

What is the effect of dilute hydrochloric acid on sulphur?

Answer 15

it doesn’t react with sulphur

Question 16

What colour is the mixture of iron and sulphur?

Answer 16

grey/yellow

Question 17

What happens if you move a magnet underneath the paper that has the iron/sulphur mixture on it?

Answer 17

the iron will follow the magnet as it moves, but the sulphur does not

Question 18

Is it easy to separate the iron/sulphur mixture?

Answer 18

yes, by using a magnet

Question 19

What happens if the iron/sulphur mixture is added to a half-filled beaker of water?

Answer 19

the iron sinks and the sulphur powder floats

Question 20

What would happen if large lumps of sulphur were used instead of sulphur powder in water?

Answer 20

they would sink

Question 21

Some of the iron/sulphur mixture is added to hydrochloric acid. What will happen?

Answer 21

The iron will react with the hydrochloric acid producing hydrogen gas and the sulfur doesn’t (it floats)

Question 22

Is hydrogen an element?

Answer 22

yes

Question 23

What are the properties that all metals have?

Answer 23

-good conducters of electricity
-good conducters of heat
-malleable
-ductile
-shiny

Question 24

What is iron (ll) sulphide?

Answer 24

It’s a compound made by combining iron and sulphur that has its own set of properties

Question 25

Is it easy or difficult to separate the elements in a compound?

Answer 25

it’s difficult

Question 26

What is the appearance of iron (ll) sulphide?

Answer 26

Black solid

Question 27

What is of iron (ll) sulphide’s density compared to water?

Answer 27

it’s more dense

Question 28

What is the effect of a magnet on iron (ll) sulphide?

Answer 28

it has no effect

Question 29

What is the effect of dilute hydrochloric acid on iron (ll) sulphide?

Answer 29

it gives off a gas that smells like rotten eggs

Question 30

What is the gas made when iron (ll) sulphide is heated with dilute hudrochloric acid?

Answer 30

hydrogen sulphide

Question 31

Is hydrogen sulphide an element, compound or mixture?

Answer 31

it’s a compound

Question 32

What colour is hydrogen sulphide?

Answer 32

colourless

Question 33

What are the two elements combined to form hydrogen sulphide?

Answer 33

Hydrogen and sulphur

Question 34

Does hydrogen sulphide have the same properties as hydrogen and sulphur?

Answer 34

no

Question 35

What is the word equation for iron and sulphur?

Answer 35

iron + sulphur → iron (ll) sulphide

Question 36

Does iron (ll) sulphide have the same properties as an iron/sulphur mixture?

Answer 36

no

Question 37

What type of reaction took place between iron and sulphur?

Answer 37

synthesis, as two elements are combined to give a singe product

Question 38

What is the name of a reaction that gives off heat?

Answer 38

exothermic