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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]
The actinide concept explained some of the observed properties of the first few actinides, namely the presence of +4 to +6 oxidation states, and proposed hybridization of the 5f and 6d orbitals, whose electrons were shown to be loosely bound in these elements. It also supported experimental results for a trend towards +3 oxidation states in the ...
Like the lanthanides, all actinides are highly reactive with halogens and chalcogens; however, the actinides react more easily. Actinides, especially those with a small number of 5f-electrons, are prone to hybridization. This is explained by the similarity of the electron energies at the 5f, 7s and 6d shells. Most actinides exhibit a larger ...
Plutonium is a transuranic radioactive chemical element, an actinide metal. Actinide chemistry (or actinoid chemistry) is one of the main branches of nuclear chemistry that investigates the processes and molecular systems of the actinides. The actinides derive their name from the group 3 element actinium.
The lanthanides obey the Oddo–Harkins rule – odd-numbered elements are less abundant than their even-numbered neighbors. Three of the lanthanide elements have radioactive isotopes with long half-lives (138 La, 147 Sm and 176 Lu) that can be used to date minerals and rocks from Earth, the Moon and meteorites. [88]
The lanthanide ions in these complexes can readily react with oxygen and water, leading to oxidation or hydrolysis, which damages the material’s structure and reduces its efficiency. This makes handling and storage difficult, requiring protective environments like sealed containers or inert gas atmospheres.
While the later actinides from americium onwards are predominantly trivalent and behave more similarly to the corresponding lanthanides, as one would expect from periodic trends, the early actinides up to plutonium (thus including thorium and uranium) have relativistically destabilised and hence delocalised 5f and 6d electrons that participate ...
The first element of the actinides, actinium gave the set its name, much as lanthanum had done for the lanthanides. The actinides are much more diverse than the lanthanides [22] and therefore it was not until 1945 that the most significant change to Dmitri Mendeleev's periodic table since the recognition of the lanthanides, the introduction of ...