3.5 Metals Flashcards
What is the structure of metallic bonding?
- lattice of positive metal ions
- sea of delocalised electrons
Define metallic bonding
electrostatic attraction between positive metal ions and negative delocalised electrons
Why do metals have high melting points?
- metallic bonding is very strong
- lots of energy needed to break
How are metals able to conduct electricity?
- delocalized electrons are free to move
Why are metals so malleable?
- layers of metal ions that can slide over each other
What are the properties of metals?
high melting points
malleable
conduct electricity
What is thermal decomposition?
heat energy used to break down a substance
What is metal carbonate decomposition?
when metal carbonate thermally decomposes to form
- metal oxide
- carbon dioxide
What does metal carbonate decomposition form?
metal oxide
carbon dioxide
What is downward delivery?
carbon dioxide sinks to the bottom of tube and remains there bc it is denser than air
What are some examples of low reactive metals?
Au
Ag
Cu
also H is here
What are Au, Ag and Cu?
low reactive metals
What are some examples of medium reactive metals?
Pb
Fe
Zn
also C is here
What are Pb, Fe and Zn?
medium reactive metals
What are some examples of high reactive metals?
C is also here
Al
Mg
Ca
Li
Na
K
How do I remember the metal reactivity series?
Au!
Agnes
Cut
Herself
Phoebe
Fell
Zamn!
Careful!
Alright
My guys
CaLifornia
Nah
K
What happens in metal + water reactions?
metal + water -> metal hydroxide + hydrogen
What is formed in metal + water reactions?
metal hydroxide + hydrogen
What are the observations of metal + water reactions?
effervescence
solid disappears
Why does effervescence occur in metal + water reactions?
hydrogen gas produced
Why does the solid disappear in metal + water reactions?
used up in the reaction
What forms when the metal + water reaction has happened?
an alkali
hydroxide is donated to water
What is different when Group 1 metals react with water?
very violent
What happens when Lithium reacts with water? (4)
solid floats
effervescence
solid moves
solid disappears
Why does the solid float when group 1 metals react with water?
less dense than water
Why does the solid move when group 1 metals react with water?
effervescence propels it around the surface of the water
What happens when Sodium reacts with water? (5)
solid floats
effervescence
solid moves
solid disappears
sodium melts
What happens when Potassium reacts with water? (6)
solid floats
effervescence
solid moves
solid disappears
potassium melts
lilac flame
What happens to group 1 metals as you go down the group?
increase in reactivity
Why do group 1 metals increase in reactivity as you go down the group?
- atoms get bigger
- have more shells
- outer-electron is further away
- attraction is weaker
- less energy needed to break attraction
What does a metal + steam reaction produce?
metal + steam -> metal oxide + hydrogen
How is metal reacting with water different than reacting with steam?
hot steam has more energy
both bonds in water molecule break
so metal oxide not hydroxide
What does a metal + acid produce?
metal + acid -> salt + hydrogen
What is a salt?
compound formed when H is displaced from an acid
What are the observations of a metal + acid reaction?
metal disappears
effervescence
Why does the metal disappear in a metal + acid reaction?
used up in reaction
Why does effervescence occur in a metal + acid reaction?
hydrogen gas is produced
What is the test for hydrogen?
lit splint -> squeaky pop
combustion of hydrogen causes test tube to resonate
The more reactive a metal is…
the faster it will react with an acid
Why cannot reactions between acids and low reactivity metals happen?
less reactive than hydrogen so cannot displace it to form the salt
Why cannot reactions between acids and high reactivity metals happen?
reaction with acids is too violent
How do displacement reactions between metals work?
more reactive metals displace less reactive metals
What observations should I consider in a metal displacement?
solid colour change
solution colour change
What are ores?
metals found in earth’s crust naturally in compound with oxygen or sulphur
What are natives?
metals that are not naturally in compound with oxygen or sulphur because they are less reactive then S or O
Give examples of metals that could form ores
C
H
Pb
Fe
Zn
C
Al
Mg
Ca
Li
Na
K
Give examples of metals that form natives
Au
Ag
Why do native metals not need to be chemically extracted?
they are so unreactive
they exist on their own
How are ores chemically extracted?
depending on their reactivity
How are high reactive metal ores chemically extracted?
using electricity
How are medium reactive metal ores and copper ore chemically extracted?
carbon extraction
metal can be displaced by heating with carbon
Why are high reactive metal ores chemically extracted using electricity?
more reactive than carbon
Why are medium reactive metal ores and copper ore chemically extracted by carbon extraction?
less reactive than carbon
Define reduction
loss of oxygen
Define oxidation
gain of oxygen
Define reducing agent
takes oxygen away
Define oxidising agent
gives oxygen
Define redox
reduction and oxidation in same reaction
What is the chemical name for rust?
hydrated iron(III) oxide
What are the properties of iron before rust?
shiny
grey
malleable
What are the properties of iron after rust?
dull
brown
brittle
What substances does rusting require?
oxygen
water
How does rusting work?
iron is oxidized by o2
iron is hydrated by water
How can rusting be prevented?
barriers
galvanisation
sacrificial protection
How do barriers prevent rusting?
paint, plastic, oil, grease
only works if coating is intact
as soon as it breaks then rusting happens
What is paint and plastic used for in barriers for preventing rusting?
stationary objects
buckets
What is oil and grease used for in barriers for preventing rusting?
moving parts
bike chains
How does sacrificial protection prevent rusting?
high reactive metal sacrifices
displaces iron from rust as soon as rust form
What is the disadvantage to using sacrificial protection to prevent rusting?
high reactive metal must be replaced often
What is the disadvantage to using barriers to prevent rusting?
only works if coating is intact
as soon as it breaks then rusting happens
How does galvanisation prevent rusting?
coating iron with zinc
coating prevents contact
zinc displaces iron
sacrificial and barrier!
What are common alloys?
steel
bronze
brass
What is steel made of?
iron + carbon
What is bronze made of?
copper + zinc
What is brass made of?
copper + tin
Why are alloys ‘harder’ than pure metals?
different sized atoms
prevents sliding of metal ions
Why are alloys not malleable?
different sized atoms
prevents sliding of metal ions
What is iron used for?
making steel
Why is iron useful?
steel is more useful than iron
What is low carbon steel made of?
Fe
0.1 % C
What is low carbon steel used for?
ships
cars
bridges
Why is low carbon steel useful?
strong
can be hammered into shape
What is high carbon steel made of?
Fe
1 % C
What is high carbon steel used for?
tools
knives
screwdrivers
Why is high carbon steel useful?
less malleable
stiff
What is stainless steel made of?
Fe
1 % C
10 % Cr
What is stainless steel used for?
cutlery
cooking utensils
kitchen sinks
Why is stainless steel useful?
Cr forms oxide layer
resists corrosion
stays shiny and clean
What is copper used for?
wires
cooking pans
water pipes
Why is copper useful?
conducts heat and electricity
unreactive
malleable
What is aluminium used for?
aircraft bodies
power cables
Why is aluminium useful?
low density
high strength
conductor
