Lanthanum is the most strongly basic of all the trivalent lanthanides, and this property is what allowed Mosander to isolate and purify the salts of this element.

The trivalent element is radioactive.

Little is known about the element but limited chemical experiments have shown that it forms a stable divalent ion in solution as well as the predicted trivalent ion that is associated with its presence as one of the actinides.

More widely, alums are double sulphate salts, with the formula, where A is a monovalent cation such as potassium or ammonium and M is a trivalent metal ion such as aluminium or chromium ( III ).

The general form of an alum is AM < sup > III </ sup >( SO < sub > 4 </ sub >)< sub > 2 </ sub >· nH < sub > 2 </ sub > O, where A is an alkali metal or ammonium, M < sup > III </ sup > is a trivalent metal, and n often is 12.

Double sulfates with the general formula, are known where A is a monovalent cation such as sodium, potassium, rubidium, caesium, or thallium ( I ), or a compound cation such as ammonium (), methylammonium (), hydroxylammonium () or hydrazinium (), B is a trivalent metal ion, such as aluminium, chromium, titanium, manganese, vanadium, iron ( III ), cobalt ( III ), gallium, molybdenum, indium, ruthenium, rhodium, or iridium.

The color of amethyst has been demonstrated to result from substitution by irradiation of trivalent iron ( Fe < sup > 3 +</ sup >) for silicon in the structure, in the presence of trace elements of large ionic radius, and, to a certain extent, the amethyst color can naturally result from displacement of transition elements even if the iron concentration is low.

This trivalent oxidation state (+ 3 ) is the most stable, especially in aqueous solutions, but tetravalent (+ 4 ) and possibly divalent (+ 2 ) berkelium compounds are also known.

This is because europium is divalent in the metallic state, and is converted into the trivalent state by the applied pressure.

The development of easy methods to separate europium from the other trivalent lanthanides made europium accessible even when present in low concentration, as it usually is.

In mathematical terms, the structure of a fullerene is a trivalent convex polyhedron with pentagonal and hexagonal faces.

These same visible lines, accompanied by the emission lines of trivalent europium and trivalent terbium, and further accompanied by the emission continuum of divalent europium in the blue region, comprise the more discontinuous light emission of the modern trichromatic phosphor systems used in many compact fluorescent lamp and traditional lamps where better color rendition is a goal.

The change is related to the sharp emission bands of the trivalent ions of these elements, acting as phosphors.

Holmium is quite electropositive and is generally trivalent.

All lanthanide elements form trivalent cations, Ln < sup > 3 +</ sup >, whose chemistry is largely determined by the ionic radius, which decreases steadily from lanthanum to lutetium.

The cation-exchange resin column as well as the HDEHP solvent extraction column elution date is consistent with a trivalent state for Md and an ionic radius smaller than Fm.

It has five electrons in its outer shell and is, therefore, trivalent in most compounds.

In the latter method, a buffered acidic solution of trivalent rare earths is treated with molten sodium-mercury alloy, which reduces and dissolves Yb < sup > 3 +</ sup >.

Hecks is yet another variant of Hex in which the tiles of the square board are irregular polygons and the graph formed by polygon edges is trivalent, i. e. each node has precisely three incident arcs.

The X site is usually occupied by divalent cations ( Ca < sup > 2 +</ sup >, Mg < sup > 2 +</ sup >, Fe < sup > 2 +</ sup >) and the Y site by trivalent cations ( Al < sup > 3 +</ sup >, Fe < sup > 3 +</ sup >, Cr < sup > 3 +</ sup >) in an octahedral / tetrahedral framework with < sup > 4 −</ sup > occupying the tetrahedra.

Johansson and Rosengren predicted in 1975 that Md would prefer a divalent metallic state, similar to europium ( Eu ) and ytterbium ( Yb ), rather than a trivalent one.

The most common example is the Erbium Doped Fiber Amplifier ( EDFA ), where the core of a silica fiber is doped with trivalent Erbium ions and can be efficiently pumped with a laser at a wavelength of 980 nm or 1, 480 nm, and exhibits gain in the 1, 550 nm region.

Ferrous ( Fe < sup > 2 +</ sup >), in chemistry, indicates a divalent iron compound (+ 2 oxidation state ), as opposed to ferric, which indicates a trivalent iron compound (+ 3 oxidation state ).

* A sulfate-based bath that uses lead anodes that are surrounded by boxes filled with sulfuric acid ( known as shielded anodes ), which keeps the trivalent chromium from oxidizing at the anodes.

There are several types of valency: impersonal (= avalent ), intransitive (= monovalent ), transitive (= divalent ) and ditransitive (= trivalent ):

One acknowledges the valency of predicates, whereby a given predicate can be avalent ( not shown ), monovalent ( laughed in the first sentence ), divalent ( helped in the second sentence ), or trivalent ( gave in the third sentence ).

The plutonium ( IV ) forms a similar complex to the uranium ( VI ), but it is possible to strip the plutonium in more than one way ; a reducing agent that converts the plutonium to the trivalent oxidation state can be added.

Before the actual discovery of mendelevium, the trivalent state was the most stable one in aqueous solution.

In the trivalent state, arsenic shows some incipient metallic properties.

There is some confusion about whether the oxidised manganese is tetravalent or trivalent.

In logic, a three-valued logic ( also trivalent, ternary, or trinary logic, sometimes abbreviated 3VL ) is any of several many-valued logic systems in which there are three truth values indicating true, false and some indeterminate third value.

In the southeastern United States, an emphatic trivalent form of eat is in use, as in I'll eat myself some supper.

A final isolation of Md < sup > 3 +</ sup > from other trivalent actinides was also required.

Methanogens typically thrive in environments in which all electron acceptors other than CO < sub > 2 </ sub > ( such as oxygen, nitrate, trivalent iron, and sulfate ) have been depleted.

Based on studies in animal models, theoretical concerns have been raised about a possible link between schizophrenia and maternal immune response activated by virus antigens ; a 2009 review concluded that there was insufficient evidence to recommend routine use of trivalent influenza vaccine during the first trimester of pregnancy, but that the vaccine was still recommended outside the first trimester and in special circumstances such as pandemics or in women with certain other conditions.

Many trivalent metals are capable of forming alums.

Other trivalent metals would also work, but gallium has a small neutron absorption cross section and helps protect the plutonium against corrosion.

Although usually trivalent, europium readily forms divalent compounds.

Like most rare earths, gadolinium forms trivalent ions which have fluorescent properties.

The elution of Md just before Fm in the elution sequence of the trivalent actinides from the cation-exchange resin column, confirmed this prediction.

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

Using the known ionic radii for the trivalent rare earths and the linear correlation of log distribution coefficient with ionic radius, an average ionic radius of 0. 089 nm was estimated for Md < sup > 3 +</ sup > and a heat of hydration of –( 3654 ± 12 ) kJ / mol calculated using empirical models and the Born-Haber cycle.

Separation of trivalent actinides from lanthanide fission products and La carrier can be done by a cation-exchange resin column using a 90 % water / 10 % ethanol solution saturated with HCl as eluant.