C3 Flashcards
simple molecule = non-metal atoms are combined to make small molecules
list the properties of a simple molecule
low melting + boiling point
most are gases or liquids
dont conduct electricity
covalent structures / macromolecules = when thousands of atoms join together
give 3 examples
diamond
graphite
silicon dioxide
properties of a diamond :
very hard
high melting point
doesnt conduct electricity
properties of graphite :
high melting point
soft and slippery
conducts electricity
structure of graphene :
graphene = ab one sheet of graphite
the carbon atoms are arranged in hexagons
held in place with 3 covalent bonds
only 1 atom thick
properties of graphene :
very strong
conducts electricity
high melting point
what are fullerenes , what can they be used for ?
hollow cage of carbon atoms
can be used as a : catalyst
lubricant
or to deliver drugs to specific parts of the body
properties of ionic substances :
high melting + boiling point
doesnt conduct electricity
however does conduct electricity when its a liquid
they dissolve in water
what type of substances combine by covalent bonding
a non metal and a non metal
covalent bonding in terms of electrons :
when atoms share electrons to get a full outer shell
describe the bonding in metals and the properties this gives rise to ?
giant structure
contains delocalised electrons
strong electrostatic attraction
positive metal ions are held in a regular pattern
why are metals malleable
because the atoms can slide past each other
what is an alloy
mixture of 2 or more metals
why are alloys stronger than pure metals ?
cos they contain a mixture of atom sizes - stops the atoms sliding
