The atomic number of the chemical element yttrium is 39 and its symbol is the letter Y. It is often called the "rare earth element" and is a silvery metallic transition metal that shares chemical similarities with the lanthanides. The rare earth minerals almost never contain yttrium alone; It is almost always found in mixture with the lanthanide elements. It is the only stable isotope and the only isotope found in the earth's crust is 89Y.
Where Yttrium is Used
LEDs and phosphors, especially red phosphors used in television cathode ray tube displays, are the two most important applications of yttrium. Also, yttrium is used to make electrodes, electrolytes, electronic filters, lasers, superconductors and other products for various medical uses and to monitor different materials to improve their quality.
The biological function of yttrium is unknown. People exposed to yttrium chemicals can develop lung conditions.
First discovered by chemist Carl Axel Arrhenius in 1787, the mineral yterbite inspired the name of the element. He named it Ytterby after the Swedish village where the mineral was found. The element was named after the mineral when the previously unexplained element yttrium was eventually discovered to be one of the compounds in yterbite.
Properties of Yttrium
Yttrium is a soft, silver-metallic, shiny and highly crystalline 3rd group transition metal. It is less electronegative than scandium, the previous member of the group, and zirconium, the next member of period 5, as predicted by periodic models.
However, it is less electronegative than lutetium, the leader of the group, as a result of lanthanide contraction. The first d-block element of the fifth phase is yttrium.
A protective oxide (Y) formed on the surface2O3) passivation of the coating explains the bulk stability of the pure element in air. When yttrium is heated to 750 °C in water vapor, this film can be formed up to 10 µm thick. However, yttrium is extremely unstable in air when finely divided; metal shavings or spins can ignite in air at temperatures above 400 °C. When the metal is heated to 1000 °C in nitrogen, it transforms into yttrium nitride (YN).
Similarity to Lanthanides
Because of how similar yttrium is to the lanthanides, it has historically been classified as a rare earth element and is always found in nature along with them as rare earth minerals. Chemically, yttrium is more similar to these elements compared to its neighbor on the periodic table, scandium. If its physical properties are plotted against its atomic number, yttrium would have an apparent number between 64,5 and 67,5, with the lanthanides located between gadolinium and erbium.
It is often in the same range in terms of reaction pattern and is similar to terbium and dysprosium in chemical reactivity. Yttrium behaves like one of the heavy lanthanide ions in solution because its size is very similar to that of the so-called "yttrium group" ions. Although the lanthanides are one row below yttrium on the periodic table, lanthanide contraction may be responsible for the similarity in atomic radius.
One of the few important differences between the chemistry of yttrium and lanthanides is that about half of the lanthanides can have valences other than three, while these other valences are important in aqueous solution for only four of the fifteen lanthanides.
Interaction of Yttrium with Other Elements
Yttrium is a trivalent transition metal that loses all three of its valence electrons to produce various inorganic compounds, typically in the +3 oxidation state. A suitable example is yttrium (III) oxide (Y2O3) is a six-coordinate white solid yttrium.
The fluoride, hydroxide, and oxalate produced by yttrium are insoluble in water, but bromide, chloride, iodide, nitrate, and sulfate are soluble in water.
Since there are no electrons in the D and F electron shells, Y3+ The ion is colorless in solution. Yttrium and its compounds easily combine with water to form Y2O3 creates. Other strong acids react rapidly with yttrium, but concentrated nitric and hydrofluoric acids do not.
At temperatures above about 200 °C, yttrium, yttrium(III) fluoride (YF)3) reacts with halogens to form trihalides such as yttrium(III) chloride (YCl3) and yttrium(III) bromide (YBr3). At high temperatures, yttrium also forms binary compounds with carbon, phosphorus, selenium, silicon, and sulfur.
The study of substances with carbon-yttrium bonds is known as organoytrium chemistry. Many of these have yttrium in oxidation state 0, which is known to exist. Organoyttrium compounds acted as catalysts for some trimerization reactions.
The starting material for these syntheses is YCl2, which is produced by reacting Y3O3 with strong hydrochloric acid and ammonium chloride.
The Greek letter η (eta) or "hapticity" is used to denote the coordination of a collection of adjacent atoms in a ligand attached to the central atom. Early examples of complexes in which carboranyl ligands bind to a d0-metal core with 7-hapticity are yttrium compounds.
Endohedral fullerenes such as Y@C82 are produced by evaporation of the graphite intercalation compounds graphite-Y or graphite-Y2O3. Studies on electron spin resonance, Y3+ and (C82)3− showed the formation of ion pairs.
Hydrocarbons, Y3C,Y2C and YC2 It can be produced by hydrolysis of carbides.
Isotopes and Star Nucleosynthesis
Through stellar nucleosynthesis, yttrium was produced in the Solar System primarily by the s-process (72%) as well as by the r-process (28%). Fast neutron capture by lighter materials occurs as part of the r-process during supernova explosions. Inside a pulsating red giant star, the s-process is the gradual neutron capture of lighter components.
The most common byproducts of nuclear fission of uranium in nuclear explosions and nuclear reactors are isotopes of yttrium. The most important yttrium isotopes for nuclear waste management are 58,51Y and 64Y, which have half-lives of 91 days and 90 hours, respectively. Although it has a short half-life, strontium-29 (90Sr), which has a half-life of 90 years, coexists with 90Y in secular equilibrium.
Due to odd atomic numbers of all group 3 elements, there are not many stable isotopes. One stable isotope exists for both yttrium and scandium, and the only naturally occurring stable isotope is 89Y. On the other hand, lanthanide contains rare earth elements, several stable isotopes, and elements with even atomic numbers.
The s-process, which gives other isotopes produced by other processes enough time to decay via electron emission (neutron → proton), is suggested to be a contributing factor to the observation that yttrium-89 is more abundant than it should normally be. Isotopes with atomic mass numbers (A = proton + neutron) roughly 50, 82, and 126 are likely to be favored by such a long process, due to the extraordinarily stable atomic nuclei with 90, 138, and 208 neutrons, respectively.
Extremely low neutron capture cross sections are hypothesized to be the reason for this stability. Due to its stability, isotopes with certain mass numbers exhibit less electron emission, which leads to their higher abundance. 90 neutrons form the core of 89Y, which has a mass number of almost 50.
There are at least 76 known synthetic isotopes of yttrium, with atomic masses ranging from 108 to 32.
The two least stable of these are 106Y and 88Y, respectively, with half-lives >150 ns and 106.626 days, respectively. All other isotopes have half-lives less than one day, and most have half-lives less than one hour, with the exception of the 58,51Y, 79,8Y, and 64Y isotopes, which have half-lives of 91 days, 87 hours, and 90 hours, respectively.
Isotopes of yttrium with a mass of 88 or less decay largely via positron emission (proton → neutron) to form isotopes of strontium (Z = 38). When isotopes of zirconium (Z = 40) are produced, isotopes of yttrium with a mass of 90 or more decay predominantly by electron emission (neutron → proton). Slightly delayed β of a few isotopes of mass 97 or greater- It is also known to exhibit neutron emission decay pathways.
At least 78 metastable (“excited”) isomers of yttrium exist, with masses ranging from 102 to 20. Many arousal states were seen for 80Y and 97Y.
While most isomers of yttrium are predicted to be less stable than their ground states, those with longer half-lives than their ground states are 78mY, 84mY, 85mY, 96mY, 98m1Y, 100mY, and 102mY and decay by beta decay rather than isomeric transition.
Source: Wikipedia
Günceleme: 18/04/2023 16:41