Structure and bonding I
Properties of ionic compounds
bonding
Structure
melting and boiling points
Solubility
arranged in a lattice structure
Strong electrostatic forces of attraction between oppositely charged ions because of the transfer of electrons transfer between non metals and metals.
High melting and boiling points
Strong ionic bonds so a large amount of energy is must be transferred to the lattice structure to break these bonds
soluble in water to form aqueous solutions
Regular arrangement of ions with ionic bonds between oppositely charged ions.
Covalent bonds
are strong
form between non-metal atoms
often produce molecules, which can be elements and compounds
low boiling and melting points because the weak intermolecular forces of attraction between molecules are weak and need little energy to overcome them
do not conduct electricity; this is because covalent compounds do not have charged particles capable of transporting electrons
conductivity
Ionic compounds conduct electricity when molten (liquid) or in aqueous solution (dissolved in water) because their ions are free to move from place to place
Simple molecular substances
Bonding
Melting and boiling points
non-conductors of electricity
solubility in water
Do not conduct electricity in any state because they are not electrically charged and do not contain free to move electrons
Some simple molecular substances break down in water forming ions which can move around allowing the solution to conduct electricity. ONLY IN AN AQUEOUS SOLUTION
Consists of a few atoms joined together by strong covalent bonds.
Low melting and boiling points because they have weak intermolecular forces. Easy to overcome these bonds
Insoluble in water because the intermolecular forces between the water and the simple covalent substance is weaker than the forces of attraction between the substances themselves.
some are soluble like chlorine, CO2, sulfur dioxide, and ammonia, ethanol and sugar.
Giant covalent molecular structures
Graphene
Structure and bonding
Consists of many atoms joined by strong covalent bonds and are arranged in a regular lattice structure
They can be non metal elements or compounds
Insoluble in water
High melting and boiling points because there are strong intermolecular forces between the molecules
Cannot conduct electricity except graphite
In graphite, each carbon atom is linked to three carbon atoms via a covalent bond. The fourth electron is delocalized so it is mobile and can conduct electricity. But diamonds have no free electrons because each carbon is four other carbon atoms covalently bonded in a tetrahedral manner.
has a regular lattice structure
Graphene is a giant molecular substance resembling a single layer of graphite
Each atom is bonded to three others
layers are just 1 atom thick and it conducts electricity because of the free to move surface ions
Fullerenes
They are sheets of graphene rolled to form hollow balls, bucky balls, and hollow tubes, nanotubes.
Conduct electricity because they have delocalised electrons
Buckminsterfullerene or C60
Soft when solid and conduct electricity because of delocalised electrons
nanotubes
Conduct electricity because of delocalised electrons. Strong because the structure has many strong covalent bonds
Allotrope
Different forms of the same element, where the atoms combine in different ways, so at the same temperature and pressure they can exist in different forms.