Covalent Bonding

Question 1

definition of covalent bonding

Answer 1

• 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

Question 2

simple molecular substances

Answer 2

• 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

Question 3

Giant covalent structures

Answer 3

• 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

Question 4

diamond

Answer 4

• 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

Question 5

graphite

Answer 5

• 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

Question 6

C60 fullerene

Answer 6

• 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