structure and bonding Flashcards
ionic structure =
ionic structure = giant ionic lattice
properties of ionic substancesand why
high melting + boiling points - a lot of energy is needed to overcome the strong electrostatic force of attraction between oppositely charged ions
most are soluble in water
non conductor as a solid - ions held in fixed positions so cannot move and carry a charge
solutions and molten ionic substances are conductors - the ionic lattice breaks down so the ions are free to move and carry a charge + energy
covalent bonding definition
sharing of pairs of outer shell electrons between non metal atoms
most covalent substances exist as..
simple covalent molecule
properties of covalent substances
low melting + boiling point - not a lot of energy is needed to overcome the weak intermolecular forces between simple covalent molecules
non conductors of electricity - there is no overall charge on molecules and there are no charged particles that can move
some covalent structures exist as what and give examples
some covalent structures exist as giant covalent structures e.g. diamond. graphite.silica (silicon dioxide)
structure of diamond
each carbon atom is bonded via 4 strong covalent bonds to 4 other carbon atom
properties of diamond
very hard - strong covalent bonds to each carbon
very high melting point - a lot of energy is needed to break strong covalent bond
non conductor - no overall charge/no charged particles free to move
structure of graphite
each carbon forms 3 strong covalent bonds with a delocalised electron from each carbon between the layers. it has layers of hexagonal rings of carbon with weak forces between the layers
graphite properties
conductor - delocalised electrons free to move between layers
soft - layers can slide due to weak forces
high melting point - a lot of energy is needed to break the many strong covalent bonds
allotrope definition
different forms of the same element which exist at the same temp and pressure
name 5 carbon allotropes
graphite,diamond and graphene,fullerenes.carbon nanotubes
fullerenes are what and using in…
fullurenes are simple molecules used in lubricants and electronics
structure of fullurenes
hollow,spherical,hexagonal/pentagonal rings of carbon
what was the first fullerene to be discovered
buckminster fullerene ( 60 carbon nanotubes)
carbon nanotubes are..
carbon nanotubes are cylandrical fullerenes with a high length to diameter ratio
properties of metals and why
electrical conductor - delocalised electrons free to move and carry a charge
high melting point - a lot of energy is needed to overcome the strong electrostatic force of attraction between positive meal ions and a sea of delocalised electrons
ductile/malleable/soft - positive metal ions are arranged in neat rows that can slide past each other whilst remaining bonded
heat/thermal conductor - energy is transferred by the delocalised electrons moving through the structure
high density - have a highly packed lattice structure ( large mass to volume ratio)
alloys are a mixture of what
alloys are a mixture of 2 or more elements where at least one of which is a metal
alkenes are
alkenes are simple covalent molecules
when are polymers formed
polymers are formed when small molecules (monomers) join together to form long chains (polymers) this is called polymerisation
polymers are..
polyers are very large simple covalent molecules
monomer -> polymer
ethene ->
vinylchloride _>
vinylacetate ->
ethene -> polyethene
vinylchloride -> polyvinylchloride
vinylacetate -> polyvinylacetate
polymers are what at room temp
polymers are solid at room temp despite being simple covalent molecules
why do polymers have high melting point
they have high melting point because they are large molecules so more energy is needed to overcome the many weak intermolecular forces between polymer chainsw
