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Flashcards in Unit 3 Deck (60)
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1

why do metals conduct electricity?

because the outer electrons are delocalised (free to move)

2

what is a metallic bond?

the electrostatic force of attraction between positively charges ions and their delocalised electrons

3

complete the equation
metal + oxygen =

metal oxide

4

complete the equation
metal + water =

metal hydroxide + hydrogen

5

complete the equation
metal + acid =

salt + hydrogen

6

how can metals be used to make soluble salts?

excess metal is added to the correct acid
mixture is filtered to remove unreacted metal
filtrate is evaporated to dryness

7

what is reduction?

gain of electrons

8

what is oxidation?

loss of electrons

9

what is a redox reaction?

when both oxidation and reduction take place at the same time

10

when a metal is extracted from its ore is a metal being oxidised or reduced?

reduced

11

what is an ore?

a compound containing useful amounts of metal ions

12

what happens to a metal ion when they are being extracted from metal ores?

they gain electrons to change from ions to atoms

13

how are very reactive metals obtained from their ores?

electrolysis

14

how can very unreactive metals be obtained from their ores?

by heat alone

15

how are most metals extracted from their ores?

heating with carbon or carbon monoxide

16

what is electrolysis?

the breaking of an ion compound into its elements using electricity

17

why must a D.C. supply be used for electrolysis?

to allow the elements to build up at the electrodes for identification

18

what happens at the electrodes during electrolysis?

positive ions gain electrons at the negative electrode
negative ions lose electrons at the positive electrodes

19

how do you make a current flow using two different metals in a solution of their own ions? (2 half cells)

connect the metals with a wire
connect the solutions with a salt bridge
the electrons will flow along the wire

20

why does graphite make a good electrode?

it is unreactive but conducts electricity

21

with a non-metal half-call how do you work out which way the electrons are going to move?

the oxidation reaction always gives electrons to the reduction reaction

22

what does a salt bridge (ion bridge) do?

it links two half cells and completes the circuit by allowing ions to pass across the bridge

23

what is an electrolyte?

a solution containing ions which can conduct electricity?

24

how can the most simple cell be made?

put 2 different metals in an electrolyte

25

what is a half-cell?

a metal in a solution of its own ions

26

do all half-cells contain a metal?

no- graphite may be used

27

which way do electrons travel in an electrochemical cell?

from the metal higher up in the electrochemical series to the one lower down

28

how does the voltage in electrochemical calls vary?

the further apart the metals are in the electrochemical series, the greater the voltage will be

29

give an example of a polymer?

plastics, starch, rubber, etc.

30

what are polymers?

long chain molecules made up by joining together lots of smaller molecules called monomers