Actinoids are highly reactive metals, especially when finely divided.

Actinoid contraction is greater for element to element than lanthanoid contraction.

Most of the trivalent Lanthanoid ions are colorless in the solid state.

Lanthanoids are good conductors of heat and electricity.

$$2Pb{(N{O_3})_2} \to 2PbO + 4N{O_2} + {O_2} \uparrow $$

$$2KCl{O_3}\buildrel \Delta \over \longrightarrow 2KCl + 3{O_2}$$

$$C{r_2}{O_3} + 2Al\buildrel \Delta \over \longrightarrow A{l_2}{O_3} + 2Cr$$

$$Fe + 2HCl \to FeC{l_2} + {H_2} \uparrow $$

Having similar chemical properties

Belonging to same group

Diagonal relationship

Lanthanoid contraction

The transition metals and their compounds are known for their catalytic activity due to their ability to adopt multiple oxidation states and to form complexes.

Interstitial compounds are those that are formed when small atoms like H, C or N are trapped inside the crystal lattices of metals.

The oxidation states of chromium in CrO₄^2- and Cr₂O₇^2- are not the same.

Cr²⁺ (d⁴) is a stronger reducing agent than Fe²⁺ (d⁶) in water.