2.3 Flashcards
what are the 4 types of solid lattice structures
giant metallic
giant covalent
giant ionic
discrete (simple) molecular
what is a metallic lattice
a regular arrangement of positive metal ions surrounded by a sea of delocalized electrons
state the properties of metallic lattices
high mp & bp
good electrical conductivity
good thermal conductivity
malleable
ductile
what is an ionic lattice
a regular arrangement of positive cations and negative anions
what are the properties of ionic lattices
high mp & bp
brittle
poor electrical conductor when solid
soluble in water
what are giant covalent lattices
giant network of atoms linked to each other by covalent bonds
what are the 4 most common examples of giant covalent lattices
diamond
graphite
graphene
silicon oxide
explain the structure of diamond
each carbon atom form 4 sigma bonds with 4 other carbon atoms
3D tetrahedral shape with bond angle of 109.5
explain the structure of graphite
each carbon atoms forms 3 sigma bonds with 3 other carbons
interlocking hexagonal rings
the 4th electron on each carbon is in a p-orbital and these electrons overlap to form a cloud of delocalised electrons both above and below the layers
explain the properties of graphite
good lubricant - due to gases adsorbed onto the surface of carbon atoms
good electrical conductor - delocalised electrons are free to move and carry charge parallel to the layers not across them
what is graphene
one atom thick layer of graphite
state 2 examples of molecular lattices
ice
iodine
explain the structure of iodine
molecules are arranged in a regular pattern creating its crystalline nature
do molecular solids have a low or high mp & bp and why
low mp & bp because there are no covalent bonds which need overcome just intermolecular forces of attraction
