9 Metals Flashcards
Metal
An element with atoms that are metallic bonded and tends to lose electrons during reactions.
NON-metal
An element that is not a metal. Tends to accept electrons during reactions.
Metallic bond
A force of attraction between a metal cation ion and a delocalised electron.
Physical properties
Specific properties of materials that do not involve changing the chemistry.
Physical properties of metals
Electrical conductivity
Thermal conductivity
High melting points and Boiling points
malleable and ductile
Why do metals conduct electricity
When metallic bonds are formed each metal atom gives up one or more of their outermost electrons. Their electrons can easily move from one atom to another (delocalised)
Chemical properties
The typical reactions of an element, compound or group of materials.
chemical properties of metals
A metal atom’s ability to lose electrons is at the heart of the reactions with important chemicals like acids, water and oxygen.
Transition metals
Form coloured compounds
Variable oxidation states
Act as catalysts
Metal reaction with dilute acid
Most metals react with dilute acids in the same way – a salt is formed and hydrogen gas is emitted.
metal + acid → salt + hydrogen
Metal reactions with water
Some metal elements are reactive enough to react with water at room temperatures. This forms a metal hydroxide and hydrogen gas.
metal + water → metal hydroxide + hydrogen
Metal reaction with oxygen
Many metals will react at room temperature with oxygen in the air. The rate of this reaction depends upon the reactivity of the metal.
metal + oxygen → metal oxide
Properties of aluminium
It has exceptionally low density but is relatively strong
Like all metals, it conducts electricity well
It is corrosion resistant; it does not need to be protected from the environment.
Uses of aluminium
Overhead cables that make up a country’s electricity power supply network
Storing food and drinks as it will not affect the taste
Properties of copper
Ductile
High conductivity
Uses of copper
Electrical equipment such as wiring and motors.
Alloys
A mixture of a metal with one or more other elements. Alloys can have different properties to the elements that they are made of.
They tend to be stronger and harder than pure metals and are therefore much more useful
What is the reactivity series of the required metals
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Hydrogen
Copper
Silver
Gold
What is the rhyme for the reactivity series of metals
Please
Send
Little
Charlies
Monkeys
And
Zebras
In
Hinged
Cages
Securely
Guarded
What metals react with cold water and what do they produce
Potassium
Sodium
Lithium
Calcium
Produces= Metal Hydroxide + H2
What metal reacts with steam only and what does it produce
Magnesium
Produces= Magnesium oxide + H2
Which metal react with acid and what do they produce
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Zinc
Iron
Produces= H2 gas + a salt
What metals do not react with water
Hydrogen
Copper
Silver
Gold
What metals do not react with acids
Hydrogen
Copper
Silver
Gold
Why is there a apparent unreactivity of aluminium in terms of its oxide layer
It creates a microscopic layer that creates a perfect barrier around the aluminium metal that prevents any further reactions between the metal and the environment. It is this protective oxide layer that makes aluminium corrosion resistant
The relative reactivities of metals in terms of their tendency to form positive ions, by
displacement reactions,
when a metal reacts with the ion of another metal, a displacement reaction occurs. The more reactive metal reduces the metal ion and makes it gain electrons to form a metal atom once again
What is brass and stainless steel made of
Brass as a mixture of copper and zinc
Stainless steel as a mixture of iron and other elements such as chromium, nickel and
carbon
Properties and use of brass
Brass is resistant to corrosion and has an attractive golden colour. These properties allow it to be used to improve the looks of objects that would come into contact with the weather, like doorknobs and letterboxes.
Properties and use of steel
It is used to make things like car engines because it is both hard and strong.
By changing what you mix with the iron you can create a variety of different steels with different properties.
For instance, high carbon steel is very hard and used to make cutting tools, like drill bits. Stainless steel is an alloy that includes iron mixed with carbon and other metals like chromium and nickel.
Chromium protects the iron within the alloy from rusting.
We can use stainless steel to make cutlery and for specialist equipment that process corrosive substances in the chemical industry.
Structure of alloys
In terms of structure how alloys can be harder and stronger than the pure metals because the different sized atoms in alloys mean the layers can no longer slide over each other
Corrosion
The chemical reaction with atmospheric oxygen that causes irreversible damage to a material.
Rusting
Rusting is the common name given to the process of oxidation of iron. Iron reacts with the oxygen and water in the air to form rust, which has the chemical name of hydrated iron(III) oxide.
iron + water + oxygen → hydrated iron(III) oxide
2Fe(s) + 2H2O(l) + O2(g) → Fe2O3·H2O(s)
Rusting is a problem as it reduces the strength of the iron or steel. If allowed to rust, objects will eventually totally disintegrate to an orange-red powder.
The presence of salt increases the rate of rusting, so metal objects in environments near the sea experience more corrosion.
Barrier methods
A set of techniques to prevent corrosion by preventing oxygen and water coming into contact with the metal surface.
Including painting, greasing and coating with plastic
Scarafictial protection
Protecting a metal from corrosion by allowing another, more reactive metal, to corrode instead.
The more reactive metals lose electrons and produce ions more easily than the protected metal
Galvanizing
Galvanising is a corrosion protection process that uses both the barrier method and sacrificial protection.
Iron or steel objects are completely coated in a thin layer of zinc. The zinc (Zn) forms a barrier between the iron and oxygen in the atmosphere.
However, if the zinc barrier is scratched or dented, then the zinc is also more reactive than the iron so it corrodes instead.
Describe the ease in obtaining metals from their ores, related to the position of the metal in the reactivity series
The more reactive a metal is, the higher up in the reactivity series it is, the harder it is to extract.
The limitations of extracting iron
The extraction of iron from hematite in the blast furnace, is limited to:
The burning of carbon (coke) to provide heat and produce carbon dioxide
The reduction of carbon dioxide to carbon monoxide
The reduction of iron(III) oxide by carbon monoxide
The thermal decomposition of calcium carbonate /limestone to produce calcium oxide
The formation of slag
Extracting iron
To extract a metal like iron a blast furnace must:
Hematite is the remain ore
heat the reaction mixture to a very high temperature
provide a chemical which can reduce the iron oxide to iron remove other impurities found in the ore, like sand, that would harm the quality of the metal being extracted.
The chemical reactions that remove the non-metal impurities when extracting iron
Carbon:
Most of the coke is combusted, but some can dissolve into the liquid iron as an impurity.
Carbon is more reactive than iron, so the oxygen in the hot air blast reacts first with the carbon.
Carbon dioxide, a gas, is released and can flow up and out of the blast furnace as exhaust gases
Sulfur:
Sulfur impurities react with oxygen in the air blast to form the waste gas sulfur dioxide, which flows up and out of the blast furnace.
Silicon: Two reactions
The calcium carbonate in the limestone thermally decomposes to become the much more reactive calcium oxide
Like most metal oxides, calcium oxide is a basic compound. The impurity silicon dioxide (silica/sand), a non-metal oxide, is acidic.
At very high temperatures calcium oxide and silicon dioxide react together to make a molten liquid called slag, which is much less dense so floats on top of the liquid iron that collects at the bottom.
Extracting aluminium
Aluminium is extracted from an ore called bauxite. The bauxite is processed to remove impurities until pure aluminium oxide, Al2O3, is produced (sometimes called alumina).
Aluminium is more reactive than carbon, so it cannot be extracted using the blast furnace, therefore electrolysis is used instead.
Chemical reactions in a blast furnace
Combustion of carbon:
carbon+oxygen→carbondioxide C(s)+O2(g)→CO2(g)
Production of carbon monoxide (incomplete combustion of carbon):
carbon dioxide + carbon → carbon monoxide
CO2(g)+C(s)→2CO(g)
Reduction of iron oxide:
iron(III) oxide + carbon monoxide → iron + carbon dioxide
Fe2O3(s)+3CO(g)→2Fe(l)+3CO2(g)
Combustion of sulfur:
sulfur + oxygen → sulfur dioxide
S(s)+O2(g)→SO2(g)
Thermal decomposition of calcium carbonate:
calcium carbonate → calcium oxide + carbon dioxide
CaCO3(s)→CaO(s)+CO2(g)
Formation of slag :
calcium oxide + silicon dioxide → slag
CaO(s)+SiO2(s)→CaSiO3(l)
Electrolysis of aluminium oxide
Purified aluminium oxide is dissolved in molten cryolite because Al2O3 melts at a high temp of (1200), cryolite is melted at 900, Al2O3’s melting point decreases and less energy is needed.
The electrodes are made of graphite, which conducts electricity. At the high temperatures used, oxygen reacts with the carbon anode producing carbon dioxide gas. This slowly erodes away the anodes, which must be regularly replaced.
Molten aluminium is denser than the cryolite and aluminium oxide solution and so sinks to the bottom and forms a layer of liquid metal, which can then be easily removed.
Ionic half equations for extraction of aluminium
At the anode:
2O2–→O2+4e–
The oxide ion is losing electrons, so it is being oxidised.
The oxygen gas produced also reacts with the graphite anode.
O2+C→CO2
At the cathode:
Al3++3e–→Al
The aluminium ion is gaining electrons, so it is being reduced.
Overall, the balanced ionic equation is this:
2Al2O3(l)→4Al(l)+3O2(g)
