Topic 2-Bonding, Structure And Properties Of Matter Flashcards
What is an ion?
Charged particles.
Why are ions formed?
Aroms lose or gain electrons to get a full outer shell so they can become stable.
What happens to metals when they form ions?
They lose electrons from their outer shell to form positive ions.
What happens to non metal when they become ions?
They gain electrons to their outer shell to form negative ions.
What happens during ionic bonding between a metal and a non metal?
The metal atom loses electrons to form a positively charged ion and non metals gain electrons to form negatively charged ions.
The opposite ions are strongly attracted by electrostatic forces. This is an ionic bond.
How is the ionic compound sodium chloride formed?
It is in a structure called a giant ionic lattice.
The are closely packed together in a regular lattice and they have very strong electrostatic forces of attraction between the oppositely charged ions in all directions.
What are the properties of ionic compounds?
They have high melting points and high boiling points due to the strong bonds between the ions so it takes alot of energy to overcome the attraction.
When they are solid they cannot conduct electricity.
When they are melted they are free to move so they carry electric current.
They dissolve easily in water so the ions are separate and are free to move in the solution so theyll carry electric current.
What happens during covalent bonding?
The positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces making covalent bonds very strong.
They only share electrons in their outer shells to give a full outer shell which makes them stable.
It happens in the compounds of non metals and in non metal elements.
What are the properties of simple molecular substances (covalent bonding)?
The molecules are held together by very strong covalent bonds but weak forces of attraction.
They melting and boiling points are low as the molecules can be easily parted as you only have to break the intermolecular forces.
Most molecular substances are gases or liquids at room temperature.
As the molecules get bigger the strength of the intermolecular forces increase so more energy is needed to break them and the melting and boiling points increase.
They dont conduct electricity as they arent charged as there are no free electrons or ions.
What is a polymer?
A long chain of repeatinf units.
How are polymers joined together?
Covalent bonds.
What are the intermolecular forces like in polymer molecules?
They are larger than simple covalent molecules so more energy is needed to break them so they are solid at room temperature.
The intermolecular forces sre still weaker than ionic or covalent bonds so they generally have lower boiling points than ionic or giant molecular compounds.
What are the structures of giant covalent structures like?
All the aroms are bonded together by strong covalent bonds.
They have high melting and boiling points as alot of energy is needed to break the covalent bonds.
They dont conduct electricity as they dont contain charged particles - not even when molton (except graphite).
What are the covalent bonds in diamond?
Each carbon atom has four covalent bonds in a rigid giant covalent structure.
What are the covalent bonds in graphite?
Each carbon atom forms three covalent bonds to create layers of hexagons.
Each carbon atom has one delocalised electron.
What is the structure of diamond?
It is a giant covalent structure with carbon atoms that form 4 covalent bonds, making diamond really hard.
The strong covalent bonds take alot of energy to break diamond giving it a very high melting point.
It doesnt conduct electricity as it has no free electrons or ions.
What is an allotrope?
A different structual form of the same element in the same physical state.
What is the structure of graphite?
Each carbon atom only forms three covalent bonds. This created sheets of carbon arranged in hexagons.
There arent any covalent bonds between the layers and are held together weakly so they are free to move over each other. This making graphite soft and slippery, like a lubricating material.
It has a high melting pint as alot of energy is needed to break the covalent bonds.
Carbon has one delocalised electron so it can conduct electricity and thermal energy.
What is the structure of grahpene?
It is a sheet of carbon atoms joined together in hexagons.
It is one atom thick making it a 2D compound.
Network of covalent bonds makes it strong.
It is light so can be added to composite materials to improve strength without adding much weight.
It has delocalised electrons so it can conduct electricity through the whole structure.
What are fullerenes?
They are molecules of carbon shaped like closed tubes or hollow balls.
What are fullerenes made up of?
Carbon atoms arranged in hexagons but can also contain pentagons or heptagons.
What are fullerenes used for?
They can cage other molecules. They can form around another atom which traps it inside. This can be used to deliver a drug into the body.
They have a huge surface area making them good industrial catalysts.
They can also be good lubricants.
What are the structure of nanotubes?
They are tiny carbon cylinders.
Theyl ratio between the length and diameter is very high.
It can conduct both electricity and thermal energy.
They have a high tensile strength (dont break when stretched).
Nanotubes can be used to strenthen materials without adding much weight.
What are the structure of metals?
They are a giant structure.
The electrons in the outer shells of the metal atoms are delocalised. There are strong forces of attraction between the positive metal ions and the negative electrons.
