Paper 2- Ionic, covalent, metallic Flashcards
What does ionic bonding involve
a metal and a non-metal
Describe ionic bonding in terms of electrostatic attractions
Ionic bonding is the electrostatic attraction between oppositely charged ions
Why do compounds with giant ionic lattices have high melting and boiling
points
- ions are held together in a closely packed 3D lattice arrangement by the attraction between oppositely charged ions
- the electrostatic attraction between oppositely charged ions is very strong
- as a result of this a lot of energy is needed to overcome the strong attraction
- hence why ionic compounds have high melting and boiling point
Do ionic compounds conduct electricity when solid?
No, ions are not free to move
Name the 3 physical properties of ionic compounds
- high melting point
- high boiling point
- can conduct electricity when molten or when dissolved in water
What do compounds with ionic bonding always have
giant ionic structure
What diagram is used to show the transfer of electrons in ionic bondidng
A dot and cross diagram
Do ionic compounds conduct electricity when liquid?
Yes, ions are free to move
Do ionic compounds conduct electricity when dissolved in a solvent?
Yes, ions are free to move
Describe covalent bonding in terms of electrostatic attractions
Covalent bonding is the electrostatic attraction between a shared pair of electrons
What is a covalent bond
A shared pair of electrons
Why are substances with a simple molecular structure gases or liquids, or
solids with low melting and boiling points
- atoms within a molecule are held together by very strong covalent bonds
- the molecular forces of attraction between the molecules are very weak
- therefore the melting and boiling point for simple molecular substances are very low as the molecules are easily separated
explain why the melting and boiling points of substances with simple molecular
structures increase, in general, with increasing relative molecular mass
- intermolecular forces are stronger between molecules with high relative molecular mass (Mr) than between smaller molecules
- as there are more points along larger molecules for intermolecular forces to act between them
- so more energy is needed to break the forces
- due to increasing strength of the forces, melting and boiling pints of simple molecular substances increase as the relative molecular mass increases
How are giant covalent structures bonded to each other
-strong covalent bonds
explain why substances with giant covalent structures are solids with high melting and
boiling points
- giant covalent structures bonded to each other by strong covalent bonds
- there are lots of these bonds so it takes a lot of energy to break them
- hence why giant covalent structures are solids with high melting and boiling points
Do Giant Covalent Structures conduct electricity
No- not even when molten
Why does diamond have a high melting and boiling point
- diamond is made up of a network of carbon atoms that each form 4 covalent bonds
- the strong covalent bonds take lots of energy to break, so diamond has a high melting point
Why is diamond hard
as the strong covalent bonds hold the electrons in a very rigid lattice structure
Why doesn’t diamond conduct electricity
as it has no free electrons or ions
Name the 3 physical properties of diamond
- high melting point
- its hard
- doesn’t conduct electricty
Why is graphite soft and slippery
- as in graphite each carbon atom only forms three covalent bonds, creating layers of carbon atoms
- layers are held together weakly by intermolecular forces of attraction so are free to slide over each other
- this makes graphite soft and slippery
Why does graphite have a high melting point
As the covalent bonds in layers require lots of energy to break
Why does graphite conduct electricity
As only three out of each of carbon’s four outer electrons are used in bonds, so each carbon atom has one electron that is delocalised (free) and can move
-hence why graphite conduct electricity
Name 2 giant covalent structures
- Graphite
- Diamond
