Inner Transition Elements — Part 2: Reactivity of lanthanoids, and the actinoids: visual lesson, ISC Class 12 Chemistry

Lesson

Reactive metals and radioactive cousins

Part 2 — how lanthanoids react, and how the actinoids differ.

In this lesson you will

Write the products formed when lanthanoids react with oxygen, hydrogen, halogens, sulphur, nitrogen, carbon, water and acids
Describe the configurations and oxidation states of the actinoids
Compare actinoids with lanthanoids and explain the wider range of actinoid oxidation states

Concept

General reactivity of the lanthanoids

Lanthanoids are soft, silvery, highly electropositive metals ( $E^\circ_{\ce{Ln^3+/Ln}}$ about −2.2 to −2.4 V). Early members (La, Ce) are about as reactive as calcium; reactivity falls slightly towards Lu as the size decreases. They tarnish quickly in moist air and usually react on heating.

Table of general properties of lanthanoid metals
Property	Lanthanoid metals
Appearance	Silvery white, tarnish in air
Hardness	Soft; harder from La to Lu
Reducing power	Strong (E° about −2.3 V)
Comparison	Early members similar to calcium

Concept

Reactions with non-metals

Ln = any lanthanoid metal. Products contain Ln³⁺.

\ce{4La + 3O2 -> 2La2O3}

\ce{2Nd + 3Cl2 -> 2NdCl3}

\ce{2Pr + N2 -> 2PrN}

Table of reactions of lanthanoid metals with oxygen, hydrogen, halogens, sulphur, nitrogen and carbon
Reagent	Condition	Product (general)
Oxygen	Burn	Ln₂O₃ (Ce gives CeO₂)
Hydrogen	Heat	LnH₂ and LnH₃
Halogens (X₂)	Heat	LnX₃
Sulphur	Heat	Ln₂S₃
Nitrogen	Heat	LnN
Carbon	2773 K	Carbides Ln₃C, Ln₂C₃, LnC₂

Cookies