{"id":322,"date":"2020-04-09T10:46:53","date_gmt":"2020-04-09T10:46:53","guid":{"rendered":"https:\/\/thechemicalelements.com\/?page_id=322"},"modified":"2023-08-15T11:48:01","modified_gmt":"2023-08-15T11:48:01","slug":"lanthanum","status":"publish","type":"post","link":"https:\/\/thechemicalelements.com\/lanthanum\/","title":{"rendered":"Lanthanum (La)"},"content":{"rendered":"\n

Lanthanum is a chemical element with atomic number 57 in the periodic table. In Earth\u2019s crust, element 57 is mainly contained as the ferromagnetic metal <\/span>cobalt<\/a> <\/span><\/i>(Co). This rare-earth metal is classified as a member of the lanthanides family of chemical elements. <\/span><\/p>\n\n\n\n

As a transition metal, lanthanum is a chemical that has three allotropic forms, as well as three valence electrons in its outer electron shell.\u00a0<\/span><\/p>\n\n\n\n

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Chemical and Physical Properties of Lanthanum<\/span><\/h3>\n\n\n\n
Property<\/strong><\/td>Value<\/strong><\/td><\/tr>
The symbol in the periodic table of elements<\/td>La<\/td><\/tr>
Atomic number<\/td>57<\/td><\/tr>
Atomic weight (mass)<\/td>138.905 g.mol-1<\/td><\/tr>
Group number<\/td>3 (Lanthanides)<\/td><\/tr>
Period<\/td>6<\/td><\/tr>
Color<\/td>A silvery-white metal<\/td><\/tr>
Physical state<\/td>Solid at room temperature<\/td><\/tr>
Half-life<\/td>From less than a minute to 1.02\u00d71011 years<\/td><\/tr>
Electronegativity according to Pauling<\/td>1.1<\/td><\/tr>
Density<\/td>6.18 g.cm-3 at 20\u00b0C<\/td><\/tr>
Melting point<\/td>920\u00b0C, 1688\u00b0F, 1193 K<\/td><\/tr>
Boiling point<\/td>3464\u00b0C, 6267\u00b0F, 3737 K<\/td><\/tr>
Van der Waals radius<\/td>0.104 nm (+3)<\/td><\/tr>
Ionic radius<\/td>1.16 (+3) \u00c5<\/td><\/tr>
Isotopes<\/td>38<\/td><\/tr>
Most characteristic isotope<\/td>139La<\/td><\/tr>
Electronic shell<\/td>[Xe] 5d16s2<\/td><\/tr>
The energy of the first ionization<\/td>539 kJ.mol-1<\/td><\/tr>
The energy of the second ionization<\/td>1098 kJ.mol-1<\/td><\/tr>
The energy of the third ionization<\/td>1840 kJ.mol-1<\/td><\/tr>
Discovery date<\/td>1839 (by Carl Gustaf Mosander)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

With the periodic table symbol La, atomic number 57, atomic mass of 138.905 g.mol<\/span>-1<\/span>, and electron configuration [Xe] 5d<\/span>1<\/span>6s<\/span>2<\/span>, lanthanum is a soft, ductile, and malleable chemical element. In fact, this transition metal is so soft that it can be dented by any firm object. <\/span><\/p>\n\n\n\n

This lanthanide exists in three allotropic forms: an \u03b1-phase (a double close-packed hexagonal structure), a \u03b2-phase (a face-centered cubic structure), and the \u03b3-phase (body-centered cubic structure). <\/span><\/p>\n\n\n\n

Lanthanum reaches its boiling point at 3464\u00b0C (6267\u00b0F or 3737 K), while its melting point is at 920\u00b0C (1688\u00b0F, 1193 K). This member of the lanthanides family of elements in the periodic table has an electronegativity of 1.1 according to Pauling, whereas the atomic radius according to van der Waals is 0.104 nm (+3) pm. <\/span><\/p>\n\n\n\n

Lanthanum rapidly oxidizes and forms La<\/span>2<\/span>O<\/span>3<\/span>. Also, it tarnishes when exposed to air. When exposed to temperatures that range from 6K (\u2212267 \u00b0C, or \u2212449 \u00b0F) all the way to its melting point, this rare earth metal also displays paramagnetic properties. <\/span><\/p>\n\n\n\n

Finally, the chemical with 57 protons in its nucleus displays a powerful magnetocaloric effect when combined with iron and silicon. In this combination, lanthanum forms cubic intermetallic compounds that can be expressed with the general chemical formula La(Fe1\u2212xSix)13.<\/span><\/p>\n\n\n\n

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How Was Lanthanum Discovered?<\/span><\/h2>\n\n\n\n

In 1839, lanthanum was discovered as the oxide (lanthana) from cerium<\/a> oxide (ceria) in Sweden. It was also one of the first elements that got classified in the lanthanides family.\u00a0<\/span><\/p>\n\n\n\n

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Carl Gustaf Mosander\u2019s Serendipitous Dicovery<\/span><\/h3>\n\n\n\n

That year, the Swedish chemist Carl Gustaf Mosander (1797 – 1858) was focused on the chemical analysis of a cerium salt sample at his workplace – the renowned Karolinska Institute. He was trying to detect the impurities that he was convinced <\/span>do <\/span><\/i>exist in the sample under his observation. <\/span><\/p>\n\n\n\n

When he triggered the chemical reaction between cerium nitrate (Ce (NO<\/span>3<\/span>)<\/span>3<\/span>) and dilute nitric acid (HNO<\/span>3<\/span>), the result was a new substance composed of two new oxides. He labeled them <\/span>lanthana<\/span><\/i> (La<\/span>2<\/span>O<\/span>3<\/span>) and <\/span>didymia<\/span><\/i>. <\/span><\/p>\n\n\n\n

While compiling his system of elements, Mendeleev had left a gap for the chemical labeled as \u2018ekaboron\u2019 that was yet to be discovered. The lanthanum oxide which Mosander discovered fitted perfectly in the intended place that was left waiting for the new element 57 in the periodic table.\u00a0<\/span><\/p>\n\n\n\n

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How Did Lanthanum Get Its Name?<\/span><\/h2>\n\n\n\n

The name of the element 57 is derived from the Ancient Greek word \u2018\u03bb\u03b1\u03bd\u03b8\u03ac\u03bd\u03b5\u03b9\u03bd\u2019 (l<\/span>anthanein<\/span><\/i>),\u00a0 meaning to \u2018lie hidden, to be concealed\u2019. This owes to the insolubility of the lanthanum ions (and generally, of the ions of all lanthanides), which makes this rare-earth element difficult to be isolated from mineral ores.\u00a0\u00a0<\/span><\/p>\n\n\n\n

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Where Can You Find Lanthanum?<\/span><\/h2>\n\n\n\n

There are approximately 0.0018% of lanthanum in the Earth\u2019s upper crust. This lanthanide has been found in the rare-earth minerals monazite and bastnaesite (also: <\/span>bastn\u00e4site<\/span>)<\/span>, cerite, and xenotime mineral ores. The mineral monazite is mineral-rich in rare-earth elements, comprising around 25% lanthanum. Thus, this mineral ore is the most exploited natural source of lanthanum. <\/span><\/p>\n\n\n\n

Lanthanum is extracted from the ores through the process of electromagnetic separation from previously crushed minerals. For commercial purposes, element 57 is acquired by crystallizing ammonium lanthanum nitrate rather than by its isolation from the mineral ores, a process that has proven to be laborious and expensive. <\/span><\/p>\n\n\n\n

While the ion-exchange and solvent extraction processes of monazite sand ((Ce, La, Th, Nd, Y)PO4) produces lanthanum in its purest form, the metal form of lanthanum is typically obtained through electrolysis of fused anhydrous halides.\u00a0<\/span><\/p>\n\n\n\n

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Lanthanum in Everyday Life<\/span><\/h2>\n\n\n\n

The pure, elemental form of lanthanum has no specific everyday uses. However, its alloys have a broad use:<\/span><\/p>\n\n\n\n