3.1 Metals and electrochemical cells Flashcards
What is metallic bonding?
( LO 1)
The attraction between positive ions and delocalised electrons
Why do metals conduct electricity?
( LO 2)
The (outer) electrons are delocalised and free to flow between outer shells
What are the 3 reactions of metals?
( LO 3)
With oxygen
With water
With acid
What is the product of reacting metals with oxygen?
A metal oxide
What are the products of reacting metals with water?
( LO 3b )
A metal hydroxide plus hydrogen
What are the products of reacting metals with acids?
( LO 3c )
A salt plus hydrogen
How many electrons do metal lose?
The number of outer electrons they have
What charge is on metal ions?
The positive charge equivalent to the number of electrons they have lost.
How does the reactivity of metals affect their reactions with water, acids, and oxygen?
( LO 4 )
How are soluble salts made using metals?
( LO 5 )
What is meant by oxidation?
( LO 6b )
The loss of electrons
Why do metals lose electrons when they react?
To obtain a full valence shell
What do we call naturally occurring metal compounds?
Ores
What are the 3 ways of extracting metals from ores?
Electrolysis ( Al and above)
Heating with carbon ( Cu to Mg)
Heating ( Below Cu)
What type of bonding is found in almost all metallic compounds?
Ionic bonding
What do we call the process of making metal ions into metal atoms during extraction?
( LO 10 )
Reduction (gain of electrons)
What are the 3 methods of extracting metals and which metals can be extracted by each method?
( LO 11 )
What is electrolysis?
( LO 13 )
The breaking apart of an ionic substance using electricity
What type of current is used in electrolysis and why?
( LO 14 )
DC current
To ensure separate products form at each electrode
What reaction happens at the negative electrode during electrolysis?
( LO 15 )
Reduction of metal ions into metal atoms.
What reaction happens at the positive electrode during electrolysis?
( LO 15 )
Oxidation
Negative ions lose electrons to form atoms (usually as molecules)
What is an electrochemical cell?
An arrangement that produces electricity through a chemical reaction (redox)
What is the set up for a simple electrochemical cell?
What is an electrolyte?
What is the purpose of the electrolyte?
To complete the circuit
Where does the reaction(s) take place in an electrochemical cell?
On the surfaces of the electrodes (metal strips)
In which direction do the electrons flow in an electrochemical cell?
From the metal higher in the electrochemcial series to the metal lower
Why is the flow of electrons through the wire lower than it should be in a simple cell?
The metal electrode that is losing electrons is in direct contact with the aqueous ions accepting them allowing direct displacement
How do we eliminate the possibility of direct displacement in an electrochemical cell?
We use a “half cell” arrangement.
What is the basic half cell arrangement using 2 metals?
2 metals sit in solutions containing their own ions. Both these solutions are joined by a salt (or ion) bridge
What are the 2 purposes of the salt (ion) bridge in a half cell arrangement
- To complete the circuit
- To maintain the charge balance in the cell
Why do cells “run out” and stop working?
The redox reaction stops due to chemicals running out.
What are advantages of using an electrochemical cells rather than mains electricity?
- safety
- portability
What are disadvantages of using an electrochemical cells rather than mains electricity?
- voltage limitations
- cost
- need replaced or recharged
