Topic C2-Bonding structure and properties of matter Flashcards
When do atoms form ions
When they lose all gain electrons
What are atoms trying to do when they become ionised
Trying to get a full outer shell-(stable electronic structure)
What happens when metals form ions and what do they form
They lose electrons from the outer shell and form positive ions
What happens when non-metals form ions and what do they form
They gain electrons into their outer shell and form negative ions
What structure does ionic compounds have
A giant ionic lattice structure
What is meant by giant ionic lattice structure
Ions form a closely packed regular lattice arrangement and there are very strong electrostatic force of attraction between oppositley charged ions in all direction in the lattice
What are the properties of ionic compounds
They all have a high boiling and melting point due to many strong bonds between the ions. It takes loads of energy to overcome these attractions
When they are solid ions are held in place so the compound cannot conduct electricity
When ionic compounds melt the ions are free to move and then carry electric current
Ionic compounds can easily be dissolved in water. The ions separate and all for free to move in the solution said their conduct electrical current
How do you work out the empirical formula of an ionic compound
1) look at the diagram to work out what ions are in the compound
2) work out what charges the ions will form
3) balance the charges of the empirical formula is zero
When do covalent bonding happen
When non-metal atoms bonded together they share pairs of electrons to make covalent bonds
What are the properties of simple molecular substances
Substances containing covalent bonds are usually have simple molecular structure
the forces of attraction between these molecules are very weak
So the melting and boiling points are very low because the molecules are easily parted from each other
Most are gases or liquids at room temperature
as molecules get bigger the intramolecular forces increase so more energy is needed to break them in boiling and melting point increases
Don’t conduct electricity simply because they aren’t charged so there are no free electrons or ions
What are polymers made out of
Are joined by strong covalent bonds
What are the properties of giant covalent structures
All the atoms are bonded to each other by strong covalent bonds
They have high melting and boiling points as loads of energy is needed to break the covalent bonds between the atoms
They don’t contact electricity as there is no charged particles not even when molten- except for graphite
What are the properties of diamond
Diamond has a giant covalent structure made up of carbon atoms that each form for covalent bonds. This makes diamond really hard
These strong covalent bonds take a lot of energy to break and a very high melting point
Doesn’t conduct electricity no free electrons or ions
What are the properties of graphite
Each carbon only forms three covalent bonds creating sheets of carbon atoms are arranged in hexagons
There aren’t any covalent bonds between the layers so only held together weakly this means that they’re free to move over each other this is why graphite is soft and slippery
High melting point- the covalent bonds need loads of energy to break
Only three out of each carbons 4 outer electrons are being used so the one electron is delocalised and can move so graphite conducts electricity and thermal energy
Why is graphene known as one layer of graphite
is a sheet of carbon atoms joined in hexagons the sheet is one atom thick making it a two-dimensional compound
The network of covalent bonds makes it very strong but incredibly light
And also has a delocalise electron so can conduct electricity through the whole structure
