Question

Give the properties of Lanthanoids.

Answer 1

The properties of lanthanoids are:

1. Soft metals with silvery white colour and moderate densities of 7 g cm^–3. Colour and brightness reduces on exposure to air.
2. Good conductors of heat and electricity.
3. Except for promethium (Pm), all are non-radioactive in nature.
4. The atomic and ionic radii decrease from lanthanum (La) to lutetium (Lu). This is known as lanthanoid contraction.
5. Binding to water is common (i.e.,) such that H₂O is often found in products when isolated from aqueous solutions.
6. Coordination numbers usually are greater than 6, typically 8, 9.... (up to 12 found).
7. The Lonthonoides are strongly paramagnetic. Gadolinium becomes ferromagnetic below 16°C (Curie point). The other heavier Lothonoids terbium, dysprosium, holmium, erbium, thulium, and ytterbium become ferromagnetic at much lower temperatures.
8. Magnetic and optical properties are Largely independent of environment (similar spectra in gas/solution/solid).