* Trivalent boron compounds such as BF < sub > 3 </ sub > have only 6 electrons in the valence shell, as do some reactive species such as carbenes.

Trivalent holmium ions have fluorescent properties similar to many other rare earth ions ( while yielding their own set of unique emission light lines ), and holmium ions are thus used in the same way as some other rare earths in certain laser and glass colorant applications.

Trivalent ions like Al < sup > 3 +</ sup > and Fe < sup > 3 +</ sup > are weak acids whose pK < sub > a </ sub > is comparable to that of acetic acid.

Trivalent chromium at low concentration is the source of the red fluorescence of ruby.

For example, one species of chromium, known as Chromium III or Trivalent Chromium, is needed by the body and causes no ill effects ; however, Chromium VI or Hexavalent Chromium, is very toxic to the body.

Trivalent chromium, which is the more common variety of chromium compounds, is not transported into cells.

Trivalent chromium ( Cr ( III )) is required in trace amounts for sugar and lipid metabolism.

Trivalent chrome ( Cr3, or Chrome III ) is commonly used in decorative applications, and is thinner and less durable than the more commonly used hexavalent chrome ( Cr6, or Chrome VI ), which is up to ten times thicker in normal applications.

Trivalent graphs can be considered as generic 1-dimensional CW-complexes.

Trivalent chromium plating, also known as tri-chrome, Cr < sup >+ 3 </ sup >, and chrome ( III ) plating, uses chromium sulfate or chromium chloride as the main ingredient.

Trivalent chromium plating is an alternative to hexavalent chromium in certain applications and thicknesses ( e. g. decorative plating ).

Trivalent titanium reduces any nitrate ion, up to 20 ppm, to ammonium ion ( i. e., reverse nitrification ).

* Fluzone Trivalent Vaccine.

It is the last element in the lanthanide series, which, along with the lanthanide contraction, explains several important properties of lutetium, such as it having the highest hardness or density among lanthanides.

In addition to the traditional metals, lanthanides, actinides, and semimetals, elements such as boron, silicon, arsenic, and selenium are considered to form organometallic compounds, e. g. organoborane compounds such as triethylborane ( Et < sub > 3 </ sub > B ).

Many lanthanides are known for their magnetic properties, such as neodymium.

Typically, the lanthanides in such monazites contain about 45 – 48 % cerium, about 24 % lanthanum, about 17 % neodymium, about 5 % praseodymium, and minor quantities of samarium, gadolinium, and yttrium.

As part of the management of minor actinides it has been proposed that the lanthanides and trivalent minor actinides should be removed from the PUREX raffinate by a process such as DIAMEX or TRUEX.

In order to allow the actinides such as americium to be either reused in industrial sources or used as fuel the lanthanides must be removed.

LCP is what remains of such mixtures, after the desirable neodymium, and all the heavier, rarer and more valuable lanthanides have been removed, by solvent extraction.

The lanthanide content is typical of " yttrium earth " minerals, and runs about two-thirds yttrium, with the remainder being mostly the heavy lanthanides, where the even-numbered lanthanides ( such as Gd, Dy, Er, or Yb ) each being present at about the 5 % level, and the odd-numbered lanthanides ( such as Tb, Ho, Tm, Lu ) each being present at about the 1 % level.

These are commonly used in industry for the processing of metals such as the lanthanides ; because the separation factors between the lanthanides are so small many extraction stages are needed.

In the high-yttrium version of these, dysprosium happens to be the most abundant of the heavy lanthanides, comprising up to 7 – 8 % of the concentrate ( as compared to about 65 % for yttrium ).

He analysed spectra of 35 elements, using the Bunsen burner, electric spark or both to induce luminescence and in this way discovered the lanthanides samarium ( 1880 ), dysprosium ( 1886 ) and europium ( 1890 ).

Actinium has similar chemical properties as lanthanum and other lanthanides, and therefore these elements are difficult to separate when extracting from uranium ores.

As with most lanthanides and actinides, actinium exists in the oxidation state + 3, and the Ac < sup > 3 +</ sup > ions are colorless in solutions.

In this system, the alkali metals, alkaline earth metals, and transition metals, as well as the lanthanides and the actinides, are special groups of the metals viewed in a broader sense.

Coordination numbers are normally between two and nine, but large numbers of ligands are not uncommon for the lanthanides and actinides.

All but one of the lanthanides are f-block elements, corresponding to the filling of the 4f electron shell ; lutetium, a d-block element, is also generally considered to be a lanthanide due to its chemical similarities with the other fourteen.

Afterwards, Md in the form of insoluble hydroxides and fluorides that are quantitatively coprecipitated with trivalent lanthanides was found.

With neodymium compounds being the most strongly colored for the trivalent lanthanides, that percentage of neodymium can occasionally dominate the coloration of rare earth minerals — when competing chromophores are absent.

Many properties of promethium rely on its position among lanthanides and are intermediate between those of neodymium and samarium.

Their corresponding effective magnetic moments, below 2µ < sub > B </ sub >, are the 3rd lowest among the lanthanides ( and their oxides ) after lanthanum and lutetium.

Although early thinking was that a higher ratio of a cation's ion charge to the size, or the charge density, resulted in more solvation, this does not stand up to scrutiny for ions like iron ( III ) or lanthanides and actinides, which are readily hydrolyzed to form insoluble ( hydrous ) oxides.

In aqueous solution the early lanthanides are surrounded by nine water molecules while the later lanthanides have a coordination number of 8.

As defined by IUPAC, rare earth elements (" REEs ") or rare earth metals are a set of seventeen chemical elements in the periodic table, specifically the fifteen lanthanides plus scandium and yttrium.

Scandium and yttrium are considered rare earth elements since they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties.

The light lanthanides are so similar in their metallurgical properties, that any application for which the original composition would have been suitable, would be equally well served by these truncated mixtures.

Scandium ( Sc ) and yttrium ( Y ) are always included, but the other two spaces are usually occupied by lanthanum ( La ) and actinium ( Ac ), or by lutetium ( Lu ) and lawrencium ( Lr ); less frequently, it is considered the group should be expanded to 32 elements ( with all the lanthanides and actinides included ) or contracted to contain only scandium and yttrium.

The group itself has not acquired a trivial name ; however, scandium, yttrium and the lanthanides are sometimes called rare earth metals.

Chromate and dichromate salts of heavy metals, lanthanides and alkaline earth metals are only very slightly soluble in water and are thus used as pigments.

Ion-exchange processes are used to separate and purify metals, including separating uranium from plutonium and other actinides, including thorium ; and lanthanum, neodymium, ytterbium, samarium, lutetium, from each other and the other lanthanides.