Atomic Structure + Structure And Bonding Flashcards
Whats the difference between a compound and a mixture
A mixture consists of two or more elements NOT chemically bonded together, where compounds are chemically combined.
What factors affect the rate of evaporation
The strength of the bonds holding the liquid together
Amount of energy in the particles
How does a covalent bond form
The positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces.
Each single covalent bond provides one extra electron for each atom and only share in their outer shells
Double bond in a diatomic molecule
Stronger than a single bond, two electrons can be shared, eg N=N
How do the size of molecules affect the melting and boiling points
There are stronger forces between molecules as the size increases, making it a higher boiling point
why small molecules and polymers do not conduct electricity.
They dont have any free electrons
Substances that contain weak intermolecular forces
Hydrogen, ammonia, methane
Structure of graphite
has flat layers of carbon atoms held by weak forces which makes Graphite a weak object and easily breakable
Structure of diamond
have a three dimensional network of strong covalent bonds, which makes it hard
Structure of fullerenes
Made up of carbon atoms shaped in hexagons
What can nanotubes be used for
They are hollow so they can be used in electronics to strengthen materials without adding weight
Metallic bonding
the strong attraction between closely packed positive metal ions and a ‘sea’ of delocalised electrons
why are metals alloyed
Because alloys contain different properties to the metals they contain
Size of a nanoparticle
Coarse - 2500-10,000nm
Fine - 100-2500nm
NANO - 1-100nm
why surface area to volume ratio increases as particle size decrease
Because the surface area is increasing
