metals Flashcards
what type of surfaces do metals have?
shiny surfaces
why do metals have high melting points and boiling points?
large amount of energy required to overcome the strong electrostatic forces of attraction between the positive ions and sea of delocalised electrons
why are metals good conductors of electricity?
delocalised electrons can move freely to act as mobile charge carriers to conduct electricity
why are metals good conductors of heat?
delocalised electrons can move freely to transfer heat from one point to another quickly as the electrons gain energy and move faster
why are metals malleable/ductile?
pure metals tend to be soft as they are arranged in orderly manner which can slide across each other easily
why do metals have high density?
atoms are closely packed together in a given volume
what is an alloy?
a mixture of a metal with one or a few other elements
why are alloys stronger and harder than the constituent pure metal?
pure metal consists of atoms of the same size which are arranged in an oderly manner. when a force is applied, the layers of atoms can slide across each other easily, in an alloy, the different size of atoms from other elements disrupts the orderly arrangement of atoms, preventing the layers of atoms from sliuding over each other easily.
what is the metal reactivity series?
potassium, sodium, calcium, magnesium, aluminium, zinc, iron, lead, (hydrogen), copper, silver, gold
what do reactive metals do?
lose electrons to form positive ions + react vigorously to form compound + have vigorrous effervesence in chemical reactions + corrode easdily when exposed to moist air/oxygen
why are reactive metals good reducing agents?
since reactive metals tend to lose electrons, it tends to oxidise itself
how do more reactive metals react with water?
metal + water -> metal hydroxide + hydrogen
how do less reactive metals react with steam?
metal + steam -> metal oxide + hydrogen
how does potassium react with cold water?
it reacts very vigorously with cold water, lilac flame observed, enough heat is produced to cause hydrogen gas to ignite and explode
how does sodium react with cold water?
react vigorously with cold water, hydrogen gas may ignite and catch fire, yellow flame observed
how does calcium react with cold water?
reacts quickly/readily with cold water
how does magnesium react with cold water?
reacts very slowly with cold water
how does aluminium/zinc/iron/lead/copper/silver/gold react with cold water?
no visible change
how does potassium/sodium/calcium react with steam?
reacts violently and explosively with steam
how does magnesium react with steam?
hot magnesium reacts vigorously with steam to produce a bright white glow, white solid formed
how does zinc react with steam?
hot zinc reacts readily with steam, yellow solid formed which turns white when cooled
how does iron react with steam?
hot iron reacts slowly with steam to form a black solid,
how does lead/copper/silver/gold react with steam?
no visible change with steam
how does potassium/sodium react with acid?
react violently and explosively with acid, effervesecne of colourless gas
how does calciumj react with acid?
reacts vigorously with acid, effervesence of colourless gas observed
how does magnesium react with acid?
reacts rapidly with acid, effersvesence of colourless gas
how does zinc react with acid?
reacts moderately fast withh acid, effervesence of colourless gas observed
how does iron react with acid?
reacts slowly with acid, slight effervesence of colourless gas
how does lead react with acid?
reacts very slowly with acid, no appparent reaction
how does copper/silver/gold react with acid?
no visible change with dilute hydrochloric acid
why does aluminium not seem react with cold water, steam or acid?
exposed aluminium reacts readily with oxygen in the air to form an inert aluminium oxide layer that protects protects aluminium metal from further reaction with cold water, steam or acid
how do displacement reactions work?
a more reactive metal displaces a less reactive metal from its salt solution
why is the less reactive metal displaced?
the more reactive metal has a higher tendency to lose electrons to form positive ions, compared to the less reactive metal
what happens when a zinc metal strip is dipped into copper (II) sulfate solution?
blue copper sulfate solution fades to colourless + pink or reddish brown solid is deposited on zinc metal strip + zinc metal strip dissolves gradually and decreases in size
why does get copper displace when a zinc metal strip is dipped into copper (II) sulfate solution?
zinc is more reactive than copper, hence zinc displaces copper from copper (II) sulfate solution, forming zinc sulfate solution and coper metal
why is there no visible reaction when iron filings are added to a magnesium sulfate solution?
iron is less reactive than magnesium and it cannot displace magnesium from magnesium sulfate
why will the mixture of zinc metal and copper oxide turn into a reddish-brown solid and a yellow solid that turns white after cooling?
zinc is more reactive than copper and will displace copper (II) oxide, producing copper metal and zinc oxide which is yellow when hot and white when cooled
what is the general reaction for the reduction of a metal oxide?
oxide of metal x + reducing agent — (reduction) –> metal X
which metal oxides are not reduced upon heating with either carbon or hydrogen?
potassium, sodium, calcium, magnesium, aluminium
how are metal oxides reduced by carbon?
metal oxide + carbon -> metal + carbon dioxide
how are metal oxides reduced by hydrogen?
metal oxide + hydrogen -> metal + steam
which metal oxides are reduced to metal upon heating with carbon, with increasing ease down the series?
zinc, iron, lead, copper
which metal oxide is reduced by heating alone?
silver
which metal oxide is not reduced to metal upon heating with hydrogen?
zinc
which metal oxide is reduced to metal upon heating with hydrogen with increasing ease down the series?
iron, lead, copper, silver
what are common reducing agents used to reduce metals?
carbon. carbon monoxide, hydrogen
what is the general reaction when metal carbonates are heated strongly?
metal carbonate -(heat)-> metal oxide + carbon dioxide
what does thermal decomposition mean?
a compound breaking down to simpler substances upon heating
`what is the relationship between the metal reactivity series and its ease to decompose when heated?
the lower the position of a metal in the reactivity series, the easier it is for the metal carbonate to decompose when heated d
why is it more difficult to decompose a reactive metals’ carbonate?
the more reactive the metal is, the more thermally stable the metal compound is
which metals carbonates are stable to heating?
potassium, sodium
which metal carbonates decompose to metal oxide and carbon dioxide with increasing ease down the series?
Ca, Mg, Al, Zn, Fe, Pb, Cu
which metal carbonate decomposes into its metal +carbon dioxide + oxygen on heating?
silver
what is the relationship between metal reactivity and the extraction method from its ores?
the more reactive the metal is, the more energy is required to break the strong bonds and extract the metal from the metal ore
which metals have to be extracted via electrolysis?
potassium, sodium, calcium, magnesium, aluminium
why can only certain metals be extracted via electrolysis?
very reactive metals form stable compounds with strong bonds, hence their compounds require a lot of energy to break down and can only be extracted by using electrolysis
which metals are extracted via reduction with carbon or carbon monoxide?
moderately reactive metals from compounds that can be reduced to metal by reacting with carbon
why can only certain metals be extracted via reduction with carbon/carbon monoxide?
metals above carbon cannot be extracted by reduction with carbon
which metals occur naturally uncombined?
silver, gold
why do unreactive metals occur naturally uncombined?
unreactive metals do not form compounds easily
what is added into the top of the blast furnace?
haematite, coke and limestone
why is coke added into the furnace?
it has a high carbon content and has little impurities and produces carbon monoxide which will reduce iron (III) oxide
what happens to the coke in a blast furnace?
it reacts with oxygen from the hot air blown in through the bottom of the furnace to form carbon dioxide
what happens to the carbon dioxide in a blast furnace?
it reacts with coke to form carbon monoxide
what does the carbon monoxide do in the blast furnace?
it reduces the iron (III) oxide in haematite to form molten iron and carbon dioxide
what is the purpose of limestone in the blast furnace?
to remove acidic impurities
what happens to the molten iron in the blast furnace?
it sinks to the bottom of the furnace and carbon dioxide escapes as hot waste gases
