What is the difference between 4f and 5f orbitals?

4f vs 5f orbitals

1. Energy level
   • 4f → fourth shell (lanthanides)
   • 5f → fifth shell (actinides)
2. Size and bonding
   • 4f → small and hidden, rarely bonds
   • 5f → bigger and more exposed, bonds more easily
3. Reactivity
   • 4f → lanthanides are less reactive
   • 5f → actinides are more reactive and variable
4. Chemistry
   • 4f → similar chemistry for all lanthanides
   • 5f → actinides show different oxidation states and complex chemistry

In short: 4f orbitals are hidden and stable; 5f orbitals are bigger, more reactive, and form more bonds.