3.1 Metals and electrochemical cells

Question 1

What is metallic bonding?

( LO 1)

Answer 1

The attraction between positive ions and delocalised electrons

Question 2

Why do metals conduct electricity?

( LO 2)

Answer 2

The (outer) electrons are delocalised and free to flow between outer shells

Question 3

What are the 3 reactions of metals?

( LO 3)

Answer 3

With oxygen

With water

With acid

Question 4

What is the product of reacting metals with oxygen?

Answer 4

A metal oxide

Question 5

What are the products of reacting metals with water?

( LO 3b )

Answer 5

A metal hydroxide plus hydrogen

Question 6

What are the products of reacting metals with acids?

( LO 3c )

Answer 6

A salt plus hydrogen

Question 7

How many electrons do metal lose?

Answer 7

The number of outer electrons they have

Question 8

What charge is on metal ions?

Answer 8

The positive charge equivalent to the number of electrons they have lost.

Question 9

How does the reactivity of metals affect their reactions with water, acids, and oxygen?

( LO 4 )

Answer 9

Question 10

How are soluble salts made using metals?

( LO 5 )

Answer 10

Question 11

What is meant by oxidation?

( LO 6b )

Answer 11

The loss of electrons

Question 12

Why do metals lose electrons when they react?

Answer 12

To obtain a full valence shell

Question 13

What do we call naturally occurring metal compounds?

Answer 13

Ores

Question 14

What are the 3 ways of extracting metals from ores?

Answer 14

Electrolysis ( Al and above)

Heating with carbon ( Cu to Mg)

Heating ( Below Cu)

Question 15

What type of bonding is found in almost all metallic compounds?

Answer 15

Ionic bonding

Question 16

What do we call the process of making metal ions into metal atoms during extraction?

( LO 10 )

Answer 16

Reduction (gain of electrons)

Question 17

What are the 3 methods of extracting metals and which metals can be extracted by each method?

( LO 11 )

Answer 17

Question 18

What is electrolysis?

( LO 13 )

Answer 18

The breaking apart of an ionic substance using electricity

Question 19

What type of current is used in electrolysis and why?

( LO 14 )

Answer 19

DC current

To ensure separate products form at each electrode

Question 20

What reaction happens at the negative electrode during electrolysis?

( LO 15 )

Answer 20

Reduction of metal ions into metal atoms.

Question 21

What reaction happens at the positive electrode during electrolysis?

( LO 15 )

Answer 21

Oxidation

Negative ions lose electrons to form atoms (usually as molecules)

Question 22

What is an electrochemical cell?

Answer 22

An arrangement that produces electricity through a chemical reaction (redox)

Question 23

What is the set up for a simple electrochemical cell?

Answer 23

Question 24

What is an electrolyte?

Answer 24

Question 25

What is the purpose of the electrolyte?

Answer 25

To complete the circuit

Question 26

Where does the reaction(s) take place in an electrochemical cell?

Answer 26

On the surfaces of the electrodes (metal strips)

Question 27

In which direction do the electrons flow in an electrochemical cell?

Answer 27

From the metal higher in the electrochemcial series to the metal lower

Question 28

Why is the flow of electrons through the wire lower than it should be in a simple cell?

Answer 28

The metal electrode that is losing electrons is in direct contact with the aqueous ions accepting them allowing direct displacement

Question 29

How do we eliminate the possibility of direct displacement in an electrochemical cell?

Answer 29

We use a "half cell" arrangement.

Question 30

What is the basic half cell arrangement using 2 metals?

Answer 30

2 metals sit in solutions containing their own ions. Both these solutions are joined by a salt (or ion) bridge

Question 31

What are the 2 purposes of the salt (ion) bridge in a half cell arrangement

Answer 31

1. To complete the circuit 2. To maintain the charge balance in the cell

Question 32

Why do cells "run out" and stop working?

Answer 32

The redox reaction stops due to chemicals running out.

Question 33

What are advantages of using an electrochemical cells rather than mains electricity?

Answer 33

* safety * portability

Question 34

What are disadvantages of using an electrochemical cells rather than mains electricity?

Answer 34

* voltage limitations * cost * need replaced or recharged