bonding and structure Flashcards
(30 cards)
what is ionic bonding
electrostatic attraction between positive and negative ions
how are ionic compounds held together
giant lattice
electrostatic between positive and negative ions holds structure together
properties of ionic substances
high melting points
do not conduct electricity when solid
conduct when molten or dissolved
what is a covalent bond
shared pair of electrons between 2 atoms
usually both non metal
structures of simple covalent
small molecules
c
don’t conduct electricity
low melting and boiling
weak intermolecular forces
what is a polymer
very larger molecules with atoms linked by covalent bonds
what are giant covalent substances
atoms bonded together in a giant lattice
example of giant covalent substances
diamond
graphite
silicon dioxide
properties of diamond
4 strong covalent bonds for each C atom
very strong
very high melting point
doesn’t conduct electricity
properties of graphite
c
why can graphite conduct electricity
one delocalised per carbon atom
properties of fullerenes
hollow shaped molecules
what carbon fullerene has a spherical shape
C60
(buckminsterfullerene)
what is graphene
single layer of graphite
what is metallic bonding
forces of attraction between delocalised electrons of metal ions
properties of metals
high melting point
good conductors
malleable
what are alloys
mixture of metal with other elements
example of an alloy
steel
why are alloys harder than pure metals
different atom sizes distort the layers and therefore cannot slide over each other
what are limitations of the simple atom model
no forces between spheres
shown as solid
intermolecular forces
forces of attraction that act with neighbouring particles
why do giant covalent substances have high melting points
lots if energy needed to break strong covalent bonds between atoms
why do small molecules have low melting points
small amount of energy needed to break weak intermolecular forces
