Chapter 7 - Networks and Nanomaterials Flashcards
where is covalent molecular bonding present
in a molecular substance made of covalent bonds
what is a covalent network lattice
where the same atoms is attached to itself 4 times creating a giant, endless and very strong structure.
e.g diamond
what is a covalent layer/planar lattice
made up of 2D covalent bonded layers of atoms with delocalised electrons flowing between layers to create weak dispersion forces. 1 atom is attached to 3 of the same atoms.
e.g graphite
properties of covalent molecular substances
low points (weak intermolecular)
poor electrical conduction in any state (no charged particles)
soft and easily scratched
properties of covalent network substances
hard (strong cos bonds in all directions)
difficult to scratch (con bonds)
high points (cov bonds)
no electrical conduction in any state
brittle
properties of covalent layer substances
soft and slippery (weak dispersion)
high points (strong cov bonds)
can conduct electricity (delocalised electrons)
what are some carbon allotropes
diamond graphite graphene nanotubes buckyballs
outline diamond
network lattice giant lattice carbon to 4 others tetrahedral all electrons involved in bonding (fixed) no electrical condution
outline graphite
2D sheets with dispersion forces holding together
each carbon to 3 others
layers slide over each other (weak dispersion)
lubricant, batteries, pencils
outline graphene
single layer of graphite
good electrical conduction (delocalised electrons)
strong (cov bonds)
computer chips, electrodes, enhancing substances strength
outline nanotubes
hexagonal structure diameter= 1nm delocalised electrons in tube good electrical conduction wiring in replace of expensive copper
outline buckyballs
buck minister fullerenes
usually 60 carbons (20 hexagons 12 pentagons)
carbon to 3 others
medicine delivery
why is diamond a good thermal conductor
because the carbon atoms are packed very closely together, when one vibrates due to heat, the adjacent vibrate also, making the hole substance conduct the heat.
what is the common name for SiO2
Quartz or silica
Describe SiO2
a covalent network lattice where each silicon atoms is bonded to 4 oxygen atoms and each oxygen atom is bonded to 2 silicon atoms. It is very hard due to the covalent bonds in all dimensions. Scratches glass easily but is not as strong as diamond due to diamond being made of only one type of atom
