C3 bonding Flashcards
how are covalent bonds formed
by atoms sharing electrons
which type of atoms form covalent bonds between them
non-metals
describe the structure and boding of a giant covalent substance
billions of atoms bonded together by strong covalent bonds
describe the structure and bonding of small molecules
small numbers of atoms group together into molecules with strong covalent bonds between the atoms and weak inter molecular forces between the molecules
describe the structure and boning of polymers
many identical molecules joined together by strong covalent bonds in a long chain, with weak intermoecular forces between the chains
why do giant covalent substances have high melting points
it takes a lot of energy to break the strong covalent bonds between the atoms
why do small molecules have low melting points
only a small amount of energy is needed to break the weak intermlecular forces
why do large molecules have higher melting and boiling points than small molecules
the intermolecular forces are stronger in large molecules
why do most covalent substances not conduct electricity
do not have delocalised electron or ions
describe the structure an bonding of graphite
each carbon atom is bonded to three others in hexagonal rings arranged in layers- it has delocalised electrons and weak forces between the layers
why can graphite conduct electricity
the delocalised electrons can move through the graphite
explain why graphite is soft
layers are not bonded so can slide over each other
what is graphene
one layer of graphite
give two properties of graphene
strong, conducts electricity
what is a fullerene
hollow cage of carbon atoms arranged as a sphere or a tube
what is a nanotube
hollow cylinder of carbon atoms
give two properties of nanotubes
high tensile strength, conduct electricity
what is an ion
atom that has lost or gained electrons
which kinds of elements form ionic bonds
a metal with a non-metal
what charges do ions from group 1 and 2 form
group 1 forms 1+, group 2 forms 2+
what charges do ions from group 6 and 7 form
group 6 forms 2-, group 7 forms 1-
name the force that holds oppositely charges ions together
electrostatic force of attraction
give three uses of fullerenes
lubricants, drug delivery (spheres), high-tech electronics
describe the structure of giant ionic lattice
regular structure of alternating positive and negative ions, held together by the electrostatic force of attraction
why don’t ionic substances conduct electricity when solid
ions are fixed in position so cannot move, and there are no delocalised electrons
why do ionic substance have higher melting points
electrostatic force between positive and negative ions is strong and requires lots of energy to break
when can ionic substances conduct electricity
when melted or dissolved
why do ionic substances conduct electricity when melted or dissolved
ions are free to move and carry charge
describe the structure of a pure metal
layers of positive metal ions surrounded by delocalised electrons
describe the bonding in a pure metal
strong electrostatic forces between metal ions and delocalised electrons
what are four properties of pure metals
malleable, high melting/boiling points, good conductors of electricity, good conductor of thermal energy
explain why pure metals are malleable
layers can slide over easily
explain why metals have high melting and boiling points
electrostatic forces between positive metal ions and delocalised electrons is strong and requires a lot of energy to break
why are metals good conductors of electricity and of thermal energy
delocalised electrons are free to move through the metal
what is an alloy
mixture of a metal with atoms of another element
explain why alloys are harder than pure metals
different sized atoms disturb the layers, preventing them from sliding over each other
how big are nano particles
1-100 nm
how are nanomaterials different from bulk materials
nanomaterials have a much higher surface area to volume ratio
what is the relationship between side length and surface area to volume ratio
as side length decreases by a factor of ten, the surface area to volume ratio increases by a factor of ten
what are nano particles used for
used in healthcare, electronics, cosmetics, and catalysts
