(11) solid state inorganic Flashcards
define crystalline materials
atoms, ions or molecules are aligned throughout the crystal in fixed orientations. No movement
how is a single crystal composed
A single crystal containing regularly repeated 3D lattice
define unit cell
smallest unit of volume which has a unique pattern from which a lattice is built
define liquid crystals
some degree of order in one or two dimensions but not as regular as a crystalline material
define amorphous material
disordered solids - solids that have a similar structure to liquids
how do you calculate the volume of a unit cell
volume = a x b x c x sinA x sinB x sinC
define coordination number
number of atoms bonded to another particular atom
define coordination geometry
arrangement of ligands around a particular atom
when coordination number = 2 what Is the name of the shape
linear or bent
when coordination number = 3 what Is the name of the shape
trigonal planar , pyramidal, t shaped
when coordination number = 4 what Is the name of the shape
tetrahedral, square planar
what are the positions of atoms within the cell defined by
fractional coordinates
what is the formula to calculate density of the crystalline solids
density = nM/(Vx 10-24 x6.023x-23) g/cm3
what is the difference between the bonding in molecular solids and network solids
molecular = van der waal network = covalent
why do molecular solids have low boiling points
van der waal intermolecular forces are the weakest so require a small amount of energy to overcome
what type of bonding has NO intermolecular forces of attraction
network solids - just covalent bonding
describe the structure within a metallic solid
- valence electrons are delocalised
- free electrons form a sea around metal ions
- ions are fixed, electrons are free
why dont atoms have fixed atomic radiuses
the radius of an atom depends on the intermolecular forces between the atoms
what is the trend between oxidation state and the atomic radiuses and why
as oxidation state increases, atomic radius decreases BECAUSE as the oxidation state increases, the net positive charge on the nucleus increases. This therefore decreases the EFFECTIVE NUCLEAR CHARGE
describe X-ray diffraction
x-ray photons are scattered by electrons surrounding the nucleus
describe electron diffraction
electrons are scattered by electrons of the atom usually in gases. Experiments must take place in a vacuum
describe neutron diffraction
scattering from the nucleus - which doesn’t depend on atomic number. This is why hydrogen can be considered a ‘heavy; element
what does single crystal x-ray/neutron diffraction produce?
It allows the calculation of individual factional coordinates of every atom in the unit cell. This can be used to calculate the fractional coordinates of the whole crystal. This generates the picture.
what does Powder x-ray/ Neutron diffraction produce
Micro crystalline powders can be used, but diffraction patterns of complex structures are difficult to determine
