Covalent Bonding Flashcards
1
Q
definition of covalent bonding
A
- atoms form covalent bonds by sharing pairs of electrons, meaning they both have full outer shells.
- strong electrostatic attraction between negative shared electrons and positive nuclei of atoms involved
2
Q
simple molecular substances
A
- atoms within a molecule are held together by very strong covalent bonds
- the forces of attraction between the molecules are very weak
- this means melting and boiling points are very low because the molecules are easily separated
- mostly gases or liquids at room temp
3
Q
Giant covalent structures
A
- all the atoms are bonded to each other by STRONG COVALENT BONDS
- there are lots of bonds which means it takes a lot of energy to break them, so giant covalent structures are SOLIDS with VERY HIGH MELTING AND BOILING POINTS
- DONT conduct electricity (except graphite)
- insoluble in water
- eg diamond and graphite
4
Q
diamond
A
- carbon atoms with 4 covalent bonds
- high melting point = hard to break covalent bonds
- rigid lattice structure = very hard
- doesn’t conduct electricity as no free electrons or ions
5
Q
graphite
A
- each carbon atom only forms 3 covalent bonds, creating layers of carbon atoms. the layers are only held together weakly by intermolecular forces so are free to slide over each other = soft and slippery
- high melting point = strong bonds within the layers
- conducts electricity = one delocalised electrons that can conduct electricity
6
Q
C60 fullerene
A
- hollow spheres of 60 carbon atoms
- not a giant covalent structure just made up of large covalent molecules
- only held together by intermolecular forces so can slide over each other = soft
- does have a delocalised electron but it cannot move between molecules so it’s a poor conductor of electricity