Bonding Flashcards
(33 cards)
What is a covalent bond
A bond formed by 2 non metals sharing electron pairs
What forms due to a covalent bond
A molecule
Why do ionic compounds have high melting points
Strong electrostatic attraction between positive and negative ions which require a lot of energy to overcome
When do ionic compounds conduct electricity
When molten or aqueous(dissolved in water)
Ions are charged and free to move
When solid the ions are fixed in an ionic lattice and can’t move
Why do simple molecular compounds have low melting and boiling points
They have weak intermolecular forces which only need little energy to break
Do simple molecular forces conduct electricity
No because they are not charged
Do giant covalent structures have high melting points
Yes because they have lots of strong covalent bonds which need a lot of energy to break
How do metals conduct electricity and heat
The positive ions are fixed
With delocalised electrons
These electrons are free to move and carry a charge
Two giant covalent structures from carbon
Graphite and diamond
Describe structure of graphite
Each carbon atom bonded to 3 other carbon atoms
Weak intermolecular forces between layer
One delocalised electron per carbon atom
Layers of hexagonal rings of carbon atoms Weak intermolecular
Describe properties of graphite
Graphite is soft and slippery - weak intermolecular forces between layers
Allowing the layers to slide
Graphite conducts electricity as there is one delocalised electron per carbon atom
Describe structure of diamond
All carbon atoms are covalent bonded to 4 carbon atoms
No delocalised electrons
Describe properties of diamond
Very hard
Very high melting point
Doesn’t conduct electricity as there are no charged particles
Uses of graphite
Lubricant as it is slippery layers slide over each other.
Electrodes because graphite conducts electricity and has a high melting point
Use of diamond
Cutting tools as it is very hard
What is a fullerene
A fullerene is a molecule made of carbon,shaped like a closed tube or hollow ball
Name 2 fullerenes
Graphene
C60 buckminsterfullerene
Properties of the fullerene
Slippery due to weak intermolecular forces
Low melting point
Large surface area
Strong covalent bonds between carbon atoms in’s molecule
Properties of graphene
High melting point due to covalent bonding between carbon atoms Weak
Conducts electricity because it has delocalised electrons
Why is graphene used in electronics
Extremely strong and delocalised electrons which are free to move and carry charge
Only one atom thick as it is a single layer of graphite
What is a polymer
Long chained molecules formed by many monomers
E.g Poly(ethene)
What are properties of metals
High melting points
High density
Good conductors of electricity
Generally shiny
Malleable and ductile
Why can metals conduct electricity
The electrons in the metals are charged that can move
Properties of non - metals
Low boiling points
Poor conductors of electricity
Brittle when solid
