Free interactive chemistry · SIM-BOND-007
Polarisation and Fajans’ rules
A small, highly charged cation distorts the electron cloud of an anion and adds covalent character (Fajans’ rules).
Open the interactive simulation →How to use this simulation
- Choose a cation and an anion.
- Watch the anion’s electron cloud bend towards the cation.
- Read the polarising power and polarisability numbers.
- Compare melting points on the bar chart.
What to notice
- Small, highly charged cations (Al³⁺, Be²⁺) and large anions (I⁻) give the most covalent character.
- More covalent character → lower melting point.
Try this
Which is more covalent, NaCl or AlCl₃? Check the melting points.
Try it for free →