UNIT 3 - Metals Flashcards
what binds the ions together in metals?
The electrostatic attraction of positive metal ions for the delocalised electrons
what is electrolysis?
It is the decomposition of an ionic compound into its elements using electricity
What is required if the products are to be identified in electrolysis?
A direct current (dc) supply
what does each atom in a metal lose, and why?
its outer electrons, to form positive ions
what do the ions form after the metal has lost its outer electrons to become an ion?
a regular three dimensional lattice of positively charged ions
describe the outer electrons of a metal atom.
they are not attached to a particular atom and are free to move around, therefore they are delocalised
what is an electrical current?
a flow of charged particles (e-, ions)
why do metals conduct electricity?
because electrons can flow through them without chemical changes taking place
what is the reactivity series in order?
- pottasium
- sodium
- lithium
- calcium
- magnesium
- aluminium
- zinc
- iron
- tin
- lead
- copper
- mercury
- silver
- gold
what is the least reactive element?
gold (does not react at all)
what do all metals above silver in the reactivity series combine with?
they combine with oxygen when heated to form a metal oxide
metal + oxygen –> metal oxide
what happens the higher up the reactivity series the element is?
the higher the metal is in the reactivity series, the more violent the reaction
what do all of the metals above aluminium react with in the reactivity series?
they react with water to form a metal hydroxide and hydrogen.
metal + water –> metal hydroxide + hydrogen
what do all of the metals above copper in the reactivity series react with?
they react with a dilute acid to create salt and hydrogen.
metal + acid –> salt + hydrogen
how can metals be placed in order of reactivity?
by comparing the rates at which they react
what is an oxidation reaction?
one in which electrons are lost or oxygen is gained
what is a reduction reaction?
one in which electrons are gained or oxygen is lost
what is a Redox reaction?
a reaction which involves both reduction and oxidation reactions taking place at the same time
what must be removed at the end of a redox reaction?
the electrons
how do you balance redox equations?
by multiplying one or both of the ion-electron eqautions
what does a displacement reaction involve?
it involves the formation of a metal from a solution containing its ions by reaction with a metal higher in the electrochemical series
what non metal appears in the ECS?
hydrogen
what does ECS stand for?
electrochemical series
how can you place hydrogen in the ECS?
you can place it according to its reaction with dilute hydrochloric acid
what is produced when metals displace hydrogen ions?
hydrogen gas
where is hydrogen in the ECS?
between LEAD and COPPER
what are ores?
they are naturally occurring compounds of metals, and most ores are oxides
what were the first metals to be found and why?
gold, silver, and copper, because they are found uncombined in the earths crust, therefore their extractions do not require a chemical reaction - they are inert
what dictates how strong a metals bonds are?
the reactivity of the metal, if the metal is very reactive then more energy is required to seperate or extract it
what type of reaction is any metal from its ore?
a reduction reaction
what can metals below copper in the reactivity series be extracted with?
heat alone
what can be reduced to their metal by heating with carbon or carbon monoxide?
oxides of metals above mercury and below aluminium in the reactivity series
what does a metal oxide + carbon create?
metal oxide + carbon –> metal + carbon dioxide
what does a metal oxide + carbon monoxide create?
metal oxide + carbon monoxide –> metal + carbon dioxide
why do metal oxide + carbon(monoxide) take place?
because the carbon bonds more strongly with the oxygen than the metal does
why does heating with carbon not work for oxides of metals above zinc?
because the metal bonds more strongly with the oxygen than the carbon does
how are all metals above zinc in the reactivity series obtained?
by the electrolysis of molten compounds using a direct current
what happens when metal compounds are in the molten state?
the ionic lattice breaks and the ions are free to move around.
how are metals formed from electrolysis?
the positive metal ions are attracted to the negative electrode, where they gain electrons and form metal atoms
what do ions flow through?
solutions
what do electrons flow through?
metal wires
what do electrochemical cells convert chemical energy into?
electrical energy
what do electrochemical cells contain?
they contain one substance which gives up electrons and another substance that takes in electrons
what does a cell consist of?
-two different metals
-an electrolyte to complete the circuit
what is an electrolyte?
a substance which completes the circuit by allowing ions to flow through it
how can metals be sorted?
they can be sorted accorded to their voltage in a league table - the ECS
what is the ECS?
a list of metals (and hydrogen) in order of their ability to lose electrons and form ions in solution
the higher a metal is in the ECS….
the more readily it loses electrons
what will electrons flow from in a cell?
the metal higher in the ECS to the metal lower down through the wires and meter
the further apart the metals are in the ECS…
the larger the voltage produced
What does a half cell consist of?
A metal in contact with a solution of it’s ions
When can electricity be produced?
Only when half two cells are joined together
How do ions move between half cells?
Using an ion bridge (salt bridge) which completes the curcuit
When can non-metals be used in half-cells?
If a graphite rod is used to make electrical contact with the solution
What will the ion higher in the ECS do?
Give away electrons
What will the ion lower in the ECS do?
Will gain the electrons given out by the ion higher in the ECS
What does a redox reaction produce?
An electric current
