2.4 Flashcards
melting point
- metallic
- ionic
- covalent
- covalent network
varies
high
low
high
volatility
metallic
ionic
covalent
covalent network
low
low
high
low
water soluble
metallic
ionic
covalent
covalent network
no
highly charged
if hydrogen bonding / polar bonds can be formed with water
no
electrical conductor
- metallic
- ionic
- covalent
- covalent network
yes
if aqueous / molten
no
no (graphite & graphene)
thermal conductor
- metallic
- ionic
- covalent
- covalent network
yes
no
no
varies
brittle
- metallic
- ionic
- covalent
- covalent network
yes
no
no (some polymers)
yes
corrode
- metallic
- ionic
- covalent
- covalent network
yes
varies
varies
no
silicon properties
metalloid - both covalent and metallic properties
lustrous like metals
covalent network
brittle
acidic oxide
semi conductor
Aluminium chloride
very low boiling point
both covalent and ionic propert
alloys
pure metallic elements mixed with other metallic or non metallic elements
properties that can be enhanced through alloys
hardness
corrosion resistance
high melting point
why r alloys stronger
unlike metals alloys contain atoms with a different radius to the cations of pure metal. so when struck with a force these layers do not slide past each other as easily
NaK (3)
low melting point
used as nuclear reactor coolant
non volatile and pumped as any other liquid
why do we make iron an alloy
Pure iron is easily deformed so we alloy it with carbon to create steel which is stronger than pure iron and can be used for construction, etc
steel rusting
steel rusts in presence of water / oxygen
rusting is problematic because it transforms iron into hydrated iron oxide
this is an ionic compound that does not have the properties of metals
rust protection methods
barrier methods: painting and oiling
sacrifical protection like galvanising
stainless steel
chromium present reacts with oxygen in the air to form a thin layer of chromium oxide which prevents rusting and is unreactive
cellulose bonds, why is it insoluble
presence of OH (hydroxyl groups) means that they can form hydrogen bonds with each other which make it stronger and insoluble in water
the hydrogen bonds are stronger than those present in water and hence its insoluble
starch
irregularly branched structure / not compact / can be easily digested by humans
plastic reactivity, structure, bonding
usually unreactive
non polar hydrocarbon
insoluble
LDFS that can be overcome by heating and solidified by cooling
plastics useful because
they are inert and do not biodegrade due to strong covalent bonds
