The lanthanide (or lanthanoid) series comprises the 15 elements with atomic numbers 57 through 71, from lanthanum to lutetium^[1]. All lanthanides are f-block elements, corresponding to the filling of the 4f electron shell, except for lutetium which is a d-block lanthanide. The lanthanide series is named after lanthanum. See also: List of elements by atomic number In chemistry and physics, the atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom. ... The periodic table of the chemical elements A chemical element, or element, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. ... General Name, Symbol, Number lanthanum, La, 57 Chemical series lanthanides Group, Period, Block 3, 6, f Appearance silvery white Atomic mass 138. ... General Name, Symbol, Number cerium, Ce, 58 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance silvery white Standard atomic weight 140. ... General Name, Symbol, Number praseodymium, Pr, 59 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance grayish white Standard atomic weight 140. ... General Name, Symbol, Number neodymium, Nd, 60 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance silvery white, yellowish tinge Standard atomic weight 144. ... General Name, Symbol, Number promethium, Pm, 61 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance metallic Atomic mass [145](0) g/mol Electron configuration [Xe] 4f5 6s2 Electrons per shell 2, 8, 18, 23, 8, 2 Physical properties Phase solid Density (near r. ... General Name, Symbol, Number samarium, Sm, 62 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance silvery white Atomic mass 150. ... General Name, Symbol, Number europium, Eu, 63 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance silvery white Atomic mass 151. ... General Name, Symbol, Number gadolinium, Gd, 64 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance silvery white Standard atomic weight 157. ... General Name, Symbol, Number terbium, Tb, 65 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance silvery white Atomic mass 158. ... General Name, Symbol, Number dysprosium, Dy, 66 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance silvery white Standard atomic weight 162. ... General Name, Symbol, Number holmium, Ho, 67 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance silvery white Atomic mass 164. ... General Name, Symbol, Number erbium, Er, 68 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance silvery white Standard atomic weight 167. ... General Name, Symbol, Number thulium, Tm, 69 Chemical series lanthanides Group, Period, Block ?, 6, f Appearance silvery gray Atomic mass 168. ... Yb redirects here; for the unit of information see Yottabit General Name, Symbol, Number ytterbium, Yb, 70 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance silvery white Standard atomic weight 173. ... General Name, Symbol, Number lutetium, Lu, 71 Chemical series lanthanides Group, Period, Block n/a, 6, d Appearance silvery white Standard atomic weight 174. ... The periodic table of the chemical elements A chemical element, or element, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. ... See also: List of elements by atomic number In chemistry and physics, the atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom. ... General Name, Symbol, Number lanthanum, La, 57 Chemical series lanthanides Group, Period, Block 3, 6, f Appearance silvery white Atomic mass 138. ... General Name, Symbol, Number lutetium, Lu, 71 Chemical series lanthanides Group, Period, Block n/a, 6, d Appearance silvery white Standard atomic weight 174. ... The f-block of the periodic table of elements consists of those elements for which, in the atomic ground state, the highest-energy electrons occupy f-orbitals. ... D Block is a rap group based in Yonkers, New York. ...

[edit] Terminology

The trivial name "rare earths" is sometimes used to describe all the lanthanides--except for promethium--together with scandium and yttrium. The term "rare earths" arises from the minerals from which they were isolated, which were uncommon oxide-type minerals. The use of this name is deprecated by IUPAC, as they are neither rare in abundance nor "earths" (an obsolete term for water-insoluble strongly basic oxides of electropositive metals incapable of being smelted into metal using late 18th century technology). These elements are in fact fairly abundant in nature, although rare as compared to the "common" earths such as lime or magnesia. Cerium is the 26th most abundant element in the Earth's crust, neodymium is more abundant than gold and even thulium (the least common naturally-occurring lanthanide) is more abundant than iodine^[2]. In chemistry, a trivial name (also common or vernacular name) is a non-systematic name. ... A rare earth is an oxide of a rare earth element. ... General Name, Symbol, Number promethium, Pm, 61 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance metallic Atomic mass [145](0) g/mol Electron configuration [Xe] 4f5 6s2 Electrons per shell 2, 8, 18, 23, 8, 2 Physical properties Phase solid Density (near r. ... General Name, Symbol, Number scandium, Sc, 21 Chemical series transition metals Group, Period, Block 3, 4, d Appearance silvery white Atomic mass 44. ... General Name, Symbol, Number yttrium, Y, 39 Chemical series transition metals Group, Period, Block 3, 5, d Appearance silvery white Standard atomic weight 88. ... The International Union of Pure and Applied Chemistry (IUPAC) is an international non-governmental organization devoted to the advancement of chemistry. ... An oxide is a chemical compound containing at least one oxygen atom and other elements. ...

IUPAC currently recommends the name lanthanoid rather than lanthanide, as the suffix "-ide" generally indicates negative ions whereas the suffix "-oid" indicates similarity to one of the members of the containing family of elements. In the older literature, the name "lanthanon" was often used. There are alternative arrangements of the periodic table that exclude lanthanum or lutetium from appearing together with the other lanthanides. The International Union of Pure and Applied Chemistry (IUPAC) is an international non-governmental organization devoted to the advancement of chemistry. ... This article is about the electrically charged particle. ...

[edit] Chemistry

Lanthanides are chemically similar to each other. Useful comparison can also be made with the actinides, where the 5f shell is partially filled. The lanthanides are typically placed below the main body of the periodic table in the manner of a footnote. The full-width version of the periodic table shows the position of the lanthanides more clearly. The actinide series encompasses the 14 chemical elements that lie between actinium and nobelium on the periodic table with atomic numbers 89 - 102 inclusive. ... This is a version of the periodic table of the elements that places all elements in the same rows. ...

The ionic radii of the lanthanides decrease through the period — the so-called lanthanide contraction. Except for cerium (III and IV) and europium (III and II), the lanthanides occur as trivalent cations in nature. As a consequence, their geochemical behaviors are a regular function of ionic radius and, therefore, atomic number. This property results in variations in the abundances of lanthanides that trace natural materials through physical and chemical processes. In addition, two of the lanthanides have radioactive isotopes with long half-lives (¹⁴⁷Sm and ¹⁷⁶Lu) that date minerals and rocks from Earth, the Moon and meteorites. The lanthanide contraction is responsible for the great geochemical divide that splits the lanthanides into light and heavy-lanthanide enriched minerals, the latter being almost inevitably associated with and dominated by yttrium. This divide is reflected in the first two "rare earths" that were discovered: yttria (1794) and ceria (1803). The divide is driven by the decrease in coordination number as the ionic radius shrinks, and is dramatically illustrated by the two anhydrous phosphate minerals, monazite (monoclinic) and xenotime (tetragonal). The geochemical divide has put more of the light lanthanides in the earths crust, but more of the heavies in the earth's mantle. The result is that although large rich orebodies are found that are enriched in the light lanthanides, correspondingly large orebodies for the heavies are few. The lanthanides obey the Oddo-Harkins rule, which states that odd-numbered elements are less abundant than their even-numbered neighbors. Ionic radius is a concept for expressing the sizes of ions in ionic crystals. ... This article or section is in need of attention from an expert on the subject. ... The Oddo-Harkins rule holds that elements with an even atomic number (such as carbon)are more common than elements with an odd atomic number(such as nitrogen). ...

Most lanthanides are widely used in lasers. These elements deflect UV and Infrared electromagnetic radiation and are commonly used in the production of sunglass lenses. For alternative meanings see laser (disambiguation). ...

Due to their specific electronic configurations, lanthanide atoms tend to lose three electrons, usually 5d¹ and 6s², to attain their most stable oxidation state as trivalent ions.

The lanthanide trications, feature a Xe core electronic configuration with the addition of n 4f electrons, with n varying from 0 [for La(III)] to 14 [for Lu(III)]. This 4fⁿ sub-shell lies inside the ion, shielded by the 5s² and 5p⁶ closed sub-shells. Thus, lanthanide trications are sometimes referred to as “triple-positively charged noble gases”.

The contracted nature of the 4f orbitals, coupled with their small overlap with the ligand atom orbitals, attaches a predominantly ionic character to lanthanide-ligand atom bonds in complexes. Thus, the mainly electrostatic interactions between the lanthanide trication and the atoms of the ligands result in irregular geometric arrangements and a handful of high coordination numbers. Indeed, this triple-positively charged closed shell inert gas electron density characteristic is the foundation of the lanthanide Sparkle Model, used in the computational chemistry of lanthanide complexes. In the context of atomic orbitals, an open shell is a valence shell which is not completely filled with electrons or that has not given all of its valence electrons through chemical bonds with other atoms or molecules during a chemical reaction. ...

Several properties, such as ionization energies, optical properties, magnetic moments and geometries of complexes, etc, serve as proof that the 4f orbitals are indeed wholly shielded from ligand effects.

[edit] Properties

All lanthanides closely resemble lanthanum. They are shiny and silvery-white, and tarnish easily when exposed to air. Many make steel. They react violently with most nonmetals. They are relatively soft but their hardness increases with their atomic number. Lanthanides burn in air. They have high melting and boiling points. General Name, Symbol, Number lanthanum, La, 57 Chemical series lanthanides Group, Period, Block 3, 6, f Appearance silvery white Atomic mass 138. ... Alternate use: Boiling Point, English title of Kitano Takeshis film 3-4X Jūgatsu; Boiling Point (TV series) The boiling point of a substance is the temperature at which it can change state from a liquid to a gas throughout the bulk of the liquid. ...

[edit] Mnemonics

To remember the sequence of the lanthanide elements, various mnemonic phrases have been used. This is the most common one: For other uses, see Mnemonic (disambiguation). ...

Ladies Can't Put Nickels Properly into Slot-machines. Every Girl Tries Daily, However, Every Time You Look.

[edit] See also

• Actinide
• Group number of lanthanides and actinides
• Rare earth element

The actinide (or actinoid) series encompasses the 15 chemical elements that lie between actinium and lawrencium on the periodic table, with atomic numbers 89 - 103[1]. The actinide series is named after actinium. ... 6 *Lanthanides 7 **Actinides IUPAC has not recommended a specific format for the periodic table, so different conventions are permitted and are often used for the group number of lanthanides and actinides. ... Rare earth ore Rare earth elements and rare earth metals are trivial names sometimes applied to a collection of 17 chemical elements in the periodic table, namely scandium, yttrium, and the lanthanides. ...

[edit] External links

• USGS Rare Earths Statistics and Information
• Ana de Bettencourt-Dias: Chemistry of the lanthanides and lanthanide-containing materials

[edit] References

1. ^ IUPAC Provisional Recommendations for the Nomenclature of Inorganic Chemistry (2004) (online draft of an updated version of the "Red Book" IR 3-6)
2. ^ Helen C Aspinall, Chemistry of the f-block elements