- solids consist of hard, incompressible, non-polarisable charged spheres
- charges are multiples of the elementary charge
- interactions are electrostatic only
evidence:
- x-ray diffraction gives electron density map
- conductivity: ionic solid is insulating but conducts electricity when molten/in aqueous solution
- appearance: brittle, non-volatile, sometimes transparent
charged spheres
ionic radii
madelung constant
lattice energy infinite series found by looking at coulomb’s law and distance between charges
born-landé equation
U=-\frac{N_{a}Z^{+}Z^{-}e^{2}A}{4\pi\epsilon_{0}r_{0}}\left( 1-\frac{1}{a} \right)
\Delta H_{L}=-\frac{\kappa\nu Z^{+}Z^{-}}{r^{+}r^{-}} \qquad \kappa=1.08\times{1}0^{5}\pu{ kJpmmol}
\Delta H_{f}=\Delta H_{atm}+\Delta H_{BE}+IE+EA+LE