Lanthanide

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Atomic No.	Name	Symbol
57	Lanthanum	La
58	Cerium	Ce
59	Praseodymium	Pr
60	Neodymium	Nd
61	Promethium	Pm
62	Samarium	Sm
63	Europium	Eu
64	Gadolinium	Gd
65	Terbium	Tb
66	Dysprosium	Dy
67	Holmium	Ho
68	Erbium	Er
69	Thulium	Tm
70	Ytterbium	Yb

The lanthanide (or lanthanoid) series comprises the 14 elements with atomic numbers 57 through 70, from lanthanum to ytterbium. All lanthanides are f-block elements, corresponding to the filling of the 4f electron shell. The lanthanide series is named after lanthanum. There are also alternative arrangements which exclude lanthanum and/or include the transition metal lutetium. The International Union of Pure and Applied Chemistry (IUPAC)'s definitions of "actinide" and "transition metal" both include lutetium, causing confusion over the element's classification, though it shares much more in common with the transition metals than with the actinides.

1 Terminology
2 Chemistry
3 Properties
4 Mnemonics
5 See also
6 External links
7 References

[edit] Terminology

The lanthanides excluding promethium, together with scandium, yttrium, and lutetium, are also sometimes referred to by the trivial name "rare earths". The term "rare earths" arises from the minerals from which they were isolated, which were uncommon oxide-type minerals (earth is an old term used to describe oxides).[1] The use of this name is deprecated by IUPAC, as they are neither rare in abundance nor "earths" (an obsolete term for oxides). These elements are infact fairly abundant in nature. Cerium is the 26^th most abundant element on the Earth, Neodymium is more abundant than gold and even Thulium (the least common naturally-occurring lanthanide) is more abundant than iodine<ref name="Aspinall">Helen C Aspinall, Chemistry of the F-block elements</ref>. IUPAC is currently recommending the name lanthanoid rather than lanthanide, as the suffix "-ide" generally indicates ions.

[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 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 are used to trace natural materials through physical and chemical processes. In addition, two of the lathanides have radioactive isotopes with long half-lives (147Sm and 176Lu) that are used to date minerals and rocks from Earth, the Moon and meteorites.

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.

[edit] Properties

All lanthanides closely resemble lanthanum. They are shiny and silvery-white. Lanthanides are shiny and tarnish easily when exposed to air. Many are used to make steel. They are violently reactive and react 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.

[edit] Mnemonics

To remember the sequence of the lanthanide elements, various mnemonic phrases have been used. This is the most common one:

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

[edit] See also

[edit] External links

[edit] References

Periodic tables
Standard table \| Vertical table \| Table with names \| Names and atomic masses (large) \| Names and atomic masses (small) \| Names and atomic masses (text only) \| Inline F-block \| Elements to 218 \| Electron configurations \| Metals and nonmetals \| Table by blocks \| Alternatives
Lists of elements
Name \| Atomic symbol \| Atomic number \| Boiling point \| Melting point \| Density \| Atomic mass
Groups: 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18
Periods: 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9
Series: Alkalis - Alkaline earths - Lanthanides - Actinides - Transition metals - Poor metals - Metalloids - Nonmetals - Halogens - Noble gases
Blocks: s-block - p-block - d-block - f-block - g-block