T2 - Covalent Bonding, Molecular and Giant Covalent Structures Flashcards
Why is C60 fullerene soft?
It has weak intermolecular forces of attraction which take little energy to overcome
Why can C60 fullerene not conduct electricity
the delocalised electrons cannot jump between different molecules
do simple molecular substances conduct electricity
they are poor conductors of electricity as there are no free ions or electrons to carry the charge
Why is graphite soft and slippery?
it has weak forces of attraction between layers - these layers can easily slide over each other
Why can graphite conduct electricity?
the delocalised electrons can move through the graphite
example of a use of diamond
coating blades in cutting tools
example of a use of graphite
in pencils
what is a molecule
a fixed number of atoms joined together by covalent bonds
What is a covalent bond
a strong electrostatic force of attraction between a shared pair of electrons and the positive nuclei that holds the atoms together
Why do substances with simple molecular substances have low melting and boiling points
they have weak intermolecular forces between molecules that are easy to overcome
Why do the melting and boiling points of substances with simple molecular structures increase, in general, with increasing molecular mass
as the molecules increase in size the molecular forces also increase as there are more electrons available this means there are more intermolecular forces of attraction that need to be overcome
why do substances with giant covalent structures have high melting and boiling points
giant covalent structures have many strong covalent bonds that take a lot of energy to overcome
What is an allotrope?
Different forms of the same element
Why is diamond hard?
diamond is extremely hard because it is a giant covalent structure with many strong covalent bonds
Why can diamond not conduct electricity?
There are no free electrons to carry electrical charge
