Unit 3- Chemistry in Society Flashcards
What is metallic bonding?
Metallic bonding is the electrostatic force of attraction between positively charged ions and delocalised electrons.
Do metals conduct electricity?
Yes
Why do metals conduct electricity?
Metallic elements are conductors of electricity because they contain delocalised electrons.
What structure does metallic bonding form?
Metallic lattice
What does a metallic lattice look like?
Positive metal ions with delocalised electrons free to move in the gaps between.
Metal + oxygen —>
metal oxide
Copper + oxygen —>
copper oxide
Metal + water —>
Metal hydroxide + hydrogen
Sodium + water —>
Sodium hydroxide + hydrogen
Metal + acid —>
Salt + hydrogen
Zinc + hydrochloric acid —>
Zinc chloride + hydrogen
What is an ion electron equation?
An equation that shows either the loss of electrons (oxidation) or the gain of electrons (reduction).
OIL RIG stands for…
Oxidation
Is
Loss of electrons
Reduction
Is
Gain of electrons
How to know if an ion electron equation is reduction or oxidation:
In an ion electron equation, if the electrons ore on the left hand side of the arrow (reduction). If they are on the right hand side of the arrow (oxidation).
The electrochemical series is arranged in order of…
Increasing reactivity
What is a redox reaction?
A redox reaction is a reaction which both reduction and oxidation takes place. Electrons are lost by one substance and gained by another.
Method for writing redox equations:
1) Decide what is being oxidised and what is being reduced, write the ion electron equation for both.
2) Multiply through so the number of electrons being lost (oxidation) is the same as the number of electrons being gained (reduction).
3) Combine the ion electron equations and cancel the electrons.
4) If you’ve done this correctly the total charge should be the same on either side.
Redox reaction notes:
Electrons do not appear in the overall redox equation.
The total charge on each side of the same.
The metal which is higher in the electrochemical series will become oxidised.
In each of the examples the negative ions present in the solutions have not been included or even referred to since they do not take part in the reaction. They are known as spectator ions.
What is a metal ore?
A rock that contains a metal compound.
What do miners call metal compounds?
Minerals
The ease at which a metal can be extracted from its metal compound depends on…
The metal’s reactivity.
What happens during the extraction of metals?
Metal ions are reduced (gain electrons) forming metal atoms.
Methods of extraction:
Heat alone (for extraction of Ag, Au and Hg)
Heating with carbon or carbon monoxide (for extraction of Cu, Pb, Sn, Fe and Zn)
Electrolysis (for extraction of more reactive metals including aluminium)
What is electrolysis?
The decomposition of an ionic compound into its elements using electricity.
A d.c. supply must be used if the products of electrolysis are to be identified.
Positive ions gain electrons at the negative electrode and negative ions lose electrons at the positive electrode.
How to make a simple cell?
A simple cell can be made by placing two metals in an electrolyte.
What is an electrolyte?
An electrically conducting solution containing ions.
What is a half-cell?
Metals in solution of their own ions.
What is an ion bridge (salt bridge)?
Filter paper soaked in sodium chloride solution.
An ion bridge can be used to like half-cells. Ions can move across the bridge to complete an electrical circuit.
How do electrons flow in electrochemical cells?
Electrons flow in the wires from the species higher in the electrochemical series to the one lower in the electrochemical series.
How to increase/decrease the voltage in an electrochemical cell?
In an electrochemical cell, different combinations of metal electrodes will affect the voltage.
The bigger the gap between the two metals on the electrochemical series, the bigger the voltage.