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The hybridization is believed to be at its greatest for cerium, which has the lowest melting point of all, 795 °C. [16] The lanthanide metals are soft; their hardness increases across the series. [1] Europium stands out, as it has the lowest density in the series at 5.24 g/cm 3 and the largest metallic radius in the series at 208.4 pm. It can ...
[21] [22] For example, the melting points of the trivalent lanthanides (all but europium and ytterbium) are related to the extent of hybridisation of the 6s, 5d, and 4f electrons (lowering with increasing 4f involvement), [23] and lanthanum has the second-lowest melting point among them: 920 °C.
Lanthanide metals react exothermically with hydrogen to form LnH 2, dihydrides. [1] With the exception of Eu and Yb, which resemble the Ba and Ca hydrides (non-conducting, transparent salt-like compounds),they form black pyrophoric, conducting compounds [6] where the metal sub-lattice is face centred cubic and the H atoms occupy tetrahedral sites. [1]
Europium is a silvery-white metal of the lanthanide series that reacts readily with air to form a dark oxide coating. It is the most chemically reactive, least dense, and softest of the lanthanide elements. It is soft enough to be cut with a knife. Europium was isolated in 1901 and named after the continent of Europe. [9]
On average for the 12 lanthanides, the melting point (on the Kelvin scale) = 1.92x the density (in g/cm^3) while the three elements following the lanthanides have similar values at 188x, 197x, and 192x before the densities continue to increase but the melting points decrease for the next 2 elements followed by both properties decreasing (at ...
La 2 O 3 powder. Lanthanum oxide is a white solid that is insoluble in water, but dissolves in acidic solutions. La 2 O 3 absorbs moisture from air, converting to lanthanum hydroxide. [2]
Lutetium is generally encountered in the 3+ oxidation state, having lost its two outermost 6s and the single 5d-electron. The lutetium atom is the smallest among the lanthanide atoms, due to the lanthanide contraction, [14] and as a result lutetium has the highest density, melting point, and hardness of the lanthanides. [15]
The ore is then roasted in the air to oxidize it to the lanthanide oxides: while most of the lanthanides will be oxidized to the sesquioxides Ln 2 O 3, cerium will be oxidized to the dioxide CeO 2. This is insoluble in water and can be leached out with 0.5 M hydrochloric acid, leaving the other lanthanides behind. [51]