Metals Flashcards
(37 cards)
Metallic bonding?
Metallic bonding is the electrostatic force of attraction between a 3 dimensional lattice of positive ions and a sea of delocalised electrons.
Metallic bonding and electrical conductivity?
Metals can conduct electricity, because the electrons (negatively charged) are free to move through the structure (delocalised) when pushed by a voltage (electric motive force). They conduct in solid/ liquid form.
Metallic bonding and malleability of metals?
Metals are malleable because they are made of hexagonal and cubic packed structures that can be moved by applying force to them. The sliding of ions when force is applied is the reason that metals can change their shapes. The ions in a metal must be moved in order to change the shape of the metal, it is easier for this to be done when it is heated.
Compare ionic and metallic bonding
E.g magnesium oxide and steel
Melting points: both high
A lot of energy need to break ionic bonds,
Strong metallic bonds
Crystallinity:
Both
Ionic form a giant lattice
Metallic have a regular lattice structure
Malleability:
Ionic no, metallic yes
Because they are made of + and - atoms that repel when they touch each other
Metallic because they can slide over each other
Alloy?
Alloys are mixtures of metals with other substances
E.g brass
Why are alloys used instead of pure metals?
Alloys contains ions of different sizes, which distort the regular arrangement of ions in the metal structure. This makes it more difficult for the layers to slide over each other, so alloys are harder than the pure metal.
Copper, gold are to soft for many uses
Changing the properties of iron?
Carbon is added to iron to form steel, which is harder that iron because of the distorted arrangments of alloys, disallowing them to slide over each other.
List the physical properties
Shiny, sonorous, conducts heat and electricity, malleable, ductile, high melting/ boiling points
Metals react with oxygen?
Form metal oxides
Sodium + oxygen — sodium oxide
Some oxide such as nitrogen monoxide
Are neutral
Oxides such as zinc oxide
Are amphoteric, they react with both acids and bases
Reactive metals react with water to form
Metal hydroxides and hydrogen
Reactions with steam and metal
Produce metal oxide and hydrogen
Reaction with metals and acid
Produce salt and hydrogen
Place in the order of reactivity, most reactive to least reactive
Potassium Sodium Calcium (All of the above react with cold water) Magnesium Aluminium Carbon ( All of the above, their oxides are not displaced by carbon) Zinc Iron (All of the above React with steam) (All of the above react with acid) Hydrogen Lead Copper
The reactivity series
Is related to the tendency of a metal to form a positive ion, by its displacement reaction or carbon. We heat metal oxides with carbon, to see where that metal would stand in the reactivity series, if the metal is dispatched by carbon it is less reactive than carbon.
E.g burning iron with carbon
The reactivity series 2
When metals react they become part of a compound, they lose their outer shell electrons to become a positive ions. Therefore the reactivity series lists the metals in order, of the ease with which they become positive ions.
Aluminium apparent unreactivity?
Aluminium oxide acts as a protective layer for aluminium. It adheres to the metal, causing aluminium to seem unreactive. However once this oxide layer is removed, aluminium reacts quickly with steam or acid for example.
What is decomposition?
The breaking down of a substance by heat
Heat on hydroxides?
Thermal decomposition
Most metal hydroxides (except group 1 metals) decompose to form metal oxide and water when heated.
All group 2 hydroxides decompose in a similar way.
Most of Group 1 metal hydroxide…
Do not decompose, except lithium hydroxide, it is the least reactive of the alkali metals.
Most metal nitrates decompose into metal oxides, nitrogen dioxide gas and oxygen gas. Group 1 nitrates….
Except lithium which behaves like other nitrates, only decompose as far as the metal nitrate and oxygen.
Nitrates are…
Very unreactive metals such silver Ag
Most metal carbonates decompose to form…
Metal oxide and carbon dioxide. Group 1 carbonates do not decompose
