Topic 9 - Metals Flashcards
What type of resources are metal ores?
Non-renewable
What process is used to extract metals from the ground?
Mining
What are the environmental impacts of mining?
Landscape scars, noise/air pollution, habitat destruction
What are the properties of copper?
Unreactive, malleable, good conductor of heat/electricity
What does malleable mean?
Can be bent easily into shape
What are 3 native metals?
Gold, platinum, silver
What is a native metal?
A metal that exists in the Earth’s crust as a pure metal
What is the most reactive metal?
Caesium
What is the least reactive metal?
Platinum
What is the reactivity of a metal linked to?
How easy it is to form its positive ion
What is a displacement reaction?
A more reactive element (metal) can remove a less reactive element (metal) from a compound.
What is a spectator ion?
An ion that doesn’t change position throughout the reaction
What is a reduction reaction?
When electrons or hydrogen are gained or oxygen is lost
What is an oxidation reaction?
When electrons or hydrogen are lost or oxygen is gained
What is the word equation for a metal reacting with water?
Metal + Water —> Metal Hydroxide + Hydrogen
What happens when K reacts with water?
It reacts very quickly; the metal and hydrogen ignite instantly, sparking and burning with a lilac flame.
What happens when Na reacts with water?
Sodium fizzes rapidly and melts to form a ball that moves around on the water surface.
What happens when Li reacts with water?
Lithium fizzes steadily and floats, becoming smaller until it eventually disappears.
What is the word equation for a metal reacting a dilute acid?
Metal + Acid —> Salt + Hydrogen
Which metals don’t react with dilute acids?
Copper, silver, gold, platinum
Which metals react with dilute acids but not cold water?
Magnesium, Aluminium, Zinc, Iron* and Lead*
*Slowly
Which metals are reactive enough to react with cold water?
Potassium, sodium, lithium
Why are most metals only found as compounds?
The metal has reacted with other elements in the past.
Why is carbon used to extract metals?
Reducing a metal with carbon will result in the extraction of the metal if the metal is lower in the reactivity series than carbon, cheap and abundant.
How is carbon used to extract metals?
Reduction with carbon normally involves heating the metal oxide in the presence of the carbon, which is often used in the form of coal. In this reduction, the metal oxide loses oxygen to form a pure metal.
Which metals are commonly extracted by reduction with carbon?
Zinc, iron, and copper
What is electrolysis?
Electrolysis is the process that splits ionic compounds into the different elements that they are made of, using a solution that conducts electricity.
What is an electrolyte?
An ionic compound that dissolves in water to make a solution that conducts electricity, due to the ions being free to move around.
What happens when a direct current is applied across an electrolyte?
The charged ions are attracted to the electrode with the opposite charge to the ion.
What are the positively charged ions attracted to?
Cathode (negative electrode)
What are the negatively charged ions attracted to?
Anode (positive electrode)
What happens when an ion touches an electrode?
Electrons can be transferred, producing elements.
What are positive ions called?
Cations
What are negative ions called?
Anions
What happens at the anode (ionic compound)?
Oxygen forms at the carbon anode, made of carbon because it is a good conductor and is cheap. The carbon and oxygen react to give carbon dioxide.
What happens at the cathode (ionic compound)?
The metal is formed at the cathode.
What are the disadvantages of electrolysis?
Lots of energy is needed, which costs a lot of money.
Why are the products of the electrolysis of aqueous solutions difficult to predict?
The water molecules in the solution split up to give hydrogen (H+) and hydroxide (OH-) ions.
What happens at the cathode (aqueous solution)?
Hydrogen is produced if the metal is higher than hydrogen in the reactivity series but the metal is produced if the metal is lower than hydrogen in the reactivity series.
What happens at the anode (aqueous solution)?
If there are halide ions present, the respective halogen forms but if there are no halide ions, oxygen forms.
What is a half equation?
During electrolysis, different reactions take place at the different electrodes and each can be shown using half equations.
What kind of reaction happens at the cathode?
Reduction
What kind of reaction happens at the anode?
Oxidation
What is iron ore also known as?
Haematite/Iron oxide
What is aluminium ore known as?
Bauxite/Aluminium oxide
What is aluminium ore mixed with for electrolysis and why?
Cryolite, because it lowers the melting point of pure aluminium oxide, reducing the temperatures needed and therefore cost.
Why can’t electrolysis be done on solids?
The charge would not flow and there would be no current.
What are the properties of transition metals?
Higher density, lower reactivity, greater strength/hardness, higher melting points
Transition metal properties - Higher density
Transition metals have more mass for the same volume than alkali metals, useful in construction.
Transition metal properties - Lower reactivity
Transition metals are less reactive than alkali metals.
Transition metal properties - Greater strength/hardness
Transition metals are stronger and harder than alkali metals.
Transition metal properties - Higher melting points
Transition metals have higher melting points than alkali metals, useful for cooking equipment.
What is iron’s melting point?
1,583°C
What is sodium’s melting point?
98°C
What are the unique properties of transition metals?
Form ions with different positive charges, form different colour compounds, catalysts
Which metals are used in catalytic converters in cars?
Platinum and Rhodium
What is the catalyst in the Haber process?
Iron
What is an alloy?
An alloy is a combination of 2+ elements, where at least 1 is a metal.
Why are alloys stronger than pure metals and useful in construction?
The ions of the different elements are of different sizes, making it harder for the layers to slide across each other when a force is applied.
Why are metals good conductors?
Their delocalised electrons carry a charge/heat within the structure, moving from the negative to the positive terminal.
What happens when a dissolved metal reacts with a sodium hydroxide solution?
The metal ions precipitate out of the solution producing insoluble solids called precipitates.
What do aluminium ions form when they react with sodium hydroxide solution?
A white precipitate of aluminium hydroxide, which can be dissolved in excess NaOH to produce a colourless solution.
What do magnesium ions form when they react with sodium hydroxide solution?
A white precipitate of magnesium hydroxide.
What do calcium ions form when they react with sodium hydroxide solution?
A white precipitate of calcium hydroxide.
What is the word equation for a dissolved metal reacting with a sodium hydroxide solution?
Metal + Hydroxide —> Metal Hydroxide
What do iron(III) ions form when they react with sodium hydroxide solution?
A brown precipitate of iron(III) hydroxide.
What do copper ions form when they react with sodium hydroxide solution?
A blue precipitate of copper(II) hydroxide.
What do iron(II) ions form when they react with sodium hydroxide solution?
A green precipitate of iron(II) hydroxide.
