C10.1 - 10.2 - Properties of metals and Reactivity series
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Properties of metals
High MP and BP Good conductors of heat Good conductors of electricity Shiny Sonorous (ring when struck) Ductile (can be drawn into wires) Malleable (can be hammered into shape)
Structure of a metal
Metal atoms give up their electrons to form positive cations. The electrons given up create a sea of delocalized electrons which are attracted to the positive ions holding the structure. This creates a strong lattice like structure for the metal
Explain why metals are malleable, ductile and good conductors of electricity relating to metallic bonding.
Good conductors of electricity: Sea of delocalized electrons in which electrons can carry current throughout a metal Ductile and malleable: Because metallic bonds are not as rigid as bonds in diamond. Ions can move around in different positions.
What is an alloy
A. mixture of a metal with one or more other elements
Why are alloys stronger than pure metals
The structure of an alloy is irregular as it contains different sized atoms from being a mixture. Due to different size atoms it’s harder to break the metal. Regular metals with repeating lattice patterns can be weak as the slightest difference between the planes of the atoms will break at that point.
Brass is an alloy of
copper and zinc Adding zinc makes the material more malleable
Bronze is an alloy of
copper and tin Adding tin increases the hardness of the material
Steel is an alloy of
iron that contains carbon
What are the different types of steel and their features
High carbon steel: Strong but brittle Used to make cutting tools and blades Low carbon steel: Soft but malleable Used in making car bodies Stainless steel (Steel containing chromium and nickel): Strong and resistant to corrosion Used in cooking utensils and cutlery
More reactive metals
react with oxygen to form oxides i.e 2Ca + O2 ==> 2CaO
Less reactive metals such as gold do not react with
oxygen
The more reactive a metal is the easier it is to
form compounds and the harder it is to break those compounds down
The most reactive metals i.e Potassium, sodium, lithium and calcium
react with water at room temperature 2Na + 2H2O ==> 2NaOh + H2
Less reactive metals such as magnesium and iron react with
steam Mg + H2O ==> MgO + H2
Some of the mid reactivity series metals produce hydrogen when react with
dilute acids Magnesium, aluminum, zinc and iron all release hydrogen when react with dilute HCI Zn + 2HCI ==> ZnCl2 + H2
Metals below hydrogen in the reactivity series do not
form hydrogen with water or dilute acids
Displacement reactions are examples of
redox reactions more reactive metal loses electrons (oxidize) and less reactive metal gains electrons (reduces)
What happens in the reaction magnesium + copper oxide
==> magnesium oxide + copper magnesium has been oxidized and gained oxygen while copper has been reduced and lost oxygen
In a redox reaction the
reducing agent is always oxidized oxidizing agent is always reduced
What happens in the displacement reaction of zinc + copper(II) sulfate solution
==> zinc sulfate solution + copper Zinc displaces copper as it is more reactivity Zinc is oxidized and copper is reduced
Why are metals dense
because atoms are packed as close as possible
Why is a metal maellable
because their regular layers make it easy to slide over each other when a force is applied