metals Flashcards
what are the general physical properties of metals?
high melting and boiling point
good conductor of heat and electricity
malleable
what happens in pure metals?
in pure metals, the atoms are of the same size and are packed in regular layers. hence, the layer of atoms can slide over each other easily when force is applied
what are alloys?
alloys are a mixture of metal and one or more other elements
they do not have a fixed melting and boiling point
what makes up steel and brass?
steel: iron and carbon
brass: copper and zinc
do all elements have the same size?
no. different elements have different atom sizes. this disrupts the regular arrangement of the pure metal, and the atoms cannot slide over each other. hence, alloys are stronger and less malleable.
what is the reactivity series abbreviation? (from most reactive to least)
please (potassium)
stop (sodium)
catching (calcium)
more (magnesium)
zebras (zinc)
i (iron)
like (lead)
having (hydrogen)
cute (copper)
short (silver)
giraffes (gold)
what metals react with cold water?
potassium, sodium, calcium, magnesium
what metals react with steam?
magnesium, zinc, iron
what metals react with acids?
potassium, sodium, calcium, magnesium, zinc, iron, lead
what metals are unreactive?
copper, silver, gold
what are metal displacement reaction called?
they are called redox reactions
a more reactive metal can displace a less reactive metal from its salt solution
what are the very reactive metals and how to extract them?
potassium, sodium, calcium, magnesium
very reactive metals can be extracted from their compounds by electrolysis (decomposition by electricity)
what are the less reactive metals and how to extract them?
zinc, iron, lead, copper, silver
less reactive metals can be extracted from their compounds by reduction with carbon and heat
what are the unreactive metals and how to extract them?
gold and platinum
unreactive metals such as gold and platinum are usually found combined
the more reactive a metal is?
the more reactive a metal is, the harder it is to extract the metal from its compound. this is because reactive metals usually form stable compounds with strong bonds
how does a blast furnace work?
1) raw materials are added to the top of the blast furnace (haematite, coke, limestone)
2)slag floasts on top of the iron
3) blast furnace is lined with a refractory material (aluminium oxide or magnesium oxide=high melting point)
what happens when extracting iron in the blast furnace?
-coke burns in the blast of hot air to produce co2 and a large amount of heat
-co2 reacts with more coke to form CO
-CO reduces iron(III) oxide to molten iron
what happens when removing impurities in the blast furnace?
thermal decomposition of limestone produces co2 and calcium oxide
the calcium oxide formed reacts with the silicon oxide and other impurities to form molten slag
how does corrosion occur?
corrosion occurs when metals react with air and water
what is the name for corrosion of iron and steel?
rusting
what speeds rusting?
sodium chloride
how can rusting be prevented?
rusting can be prevented by coating the metal with a protective layer (oil, paint, plastic). this prevents water and oxygen from reacting with the iron. however, if the layer is scratched or broken, rusting will occur
what kind of resources are metals?
they are finite sources
what are the advantages of recycling?
-they conserve and slow down the depletion of natural sources
do this by conserving finite metal ores and limited fossil fuels reserves(extraction requires high energy and burning of fossil fuels, which is also a finite source)
-economically
saves the cost of extracting new metals from ores
reduce cost as lesser landfill sites need to be built
-environmentally
lesser environmental problems and pollution as compared to extraction
