Actinide

Actinides [- noi ː də ] (" Actiniumähnliche "; Greek: ending- οειδής ( - oeides ) "similar" ) is a group designation of certain similar elements. Ironically the course you are Actinium and the following 14 elements in the periodic table: thorium, protactinium, uranium and transuranic elements neptunium, plutonium, americium, curium, berkelium, californium, einsteinium, fermium, Mendelevium, nobelium and Lawrencium. Within the meaning of the term is not part of the actinium Actiniumähnlichen. Here the nomenclature of the IUPAC accepted but the practical use. The earlier name actinides does not correspond to the proposal from the Commission nomenclature, as is reserved for this the ending " - id" for binary compounds such as chlorides; the designation continue to be permitted. All actinides are metals and are also referred to as elements of the actinium series.

• 3.1 oxides
• 3.2 halides

Conceptual delimitation

• The transuranium elements are the elements with a higher atomic number than uranium, ie the actinides starting with neptunium (93 ) are also transuranic elements.
• As transactinides are the elements with atomic numbers from 104 ( rutherfordium ). Follow in the periodic table on the actinides. All transactinides are also simultaneously Transuranium Elements, because they have atomic numbers greater than that of uranium.

Properties

Physical Properties

All actinides are radioactive and are among the metals. Some are pyrophoric in a finely divided state. The actinides include as the lanthanides of the inner transition elements, or f -block elements, since these rows, the bottom shells F to be filled with electrons.

Chemical Properties

All actinides form triply charged ions, they are like the actinium regarded as a subgroup of the subgroup 3. The " lighter " actinides ( thorium to americium ) occur in a larger number of oxidation states than the corresponding lanthanides.

Colors of actinide ions in aqueous solution

Compounds

Oxides

The tetravalent actinide oxides crystallize in the cubic crystal system; the structure type is the CaF2 type ( fluorite ) with space group Fm3m and the coordination numbers An, O.

Halides

The trivalent actinide chlorides crystallize in the hexagonal crystal system. The structure of uranium (III ) chloride is the lead for a number of other compounds. In that the metal atoms are surrounded by nine each chlorine atoms. As coordination polyhedra there arises a triple überkapptes, trigonal prism, as is often also found in the later actinides and lanthanides. It crystallizes in the hexagonal crystal system, space group P63 / m and two formula units per unit cell.