12B.2 Flashcards
what is experimental lattice energy
it is a lattice energy calculated from the born-haber cycle
the type of lattice structure and the inter ion distance can be found by
X-ray crystallography
to calculate the lattice energy what assumptions do we make
- the ions are in contact with each other
- the ions are perfectly spherical
3, the charge of the ions is evenly distributed in the centre making the ions be considered as a point of charge
what is theoretical lattice energy
lattice energy that is calculated using the principles of electrostatics
why are the theoretical values of lattice energy sometimes less that the experimental lattice energies
because in theoretical lattice energy the covalent character caused by the polarization of the anion is not included
what is polarization
the distortion of electron density of an anion
why does polarization form a covalent character
because the polarization of the anion causes the distribution of the electron density of the anion which would result in a higher electron density in the cation so there will be some electron density between the two ions = covalent character
polarization will increase by
- small cation + high charge
- big anion + high charge
what is polarization power
the ability of a cation to attract the anion electrons to its self
more polarization is a result of
more polarization power of the cation
charge density
charge / r^2
greater covalent character (bond) is a result of
greater polarization
what ions are easiest to polarize
high charge + large size
