Key Chemical Properties and Applications of Gadolinium
With over 13 natural isotopes and known for its wide range of applications today, Gadolinium is the 66th element in the Periodic Table. Denoted as Gd, this element is classified under the section of lanthanides. Malleability, solubility, ductility, and high thermal stability are all the notable features of this chemical element. The important, booming fields of technology and medical sciences, prefer Gadolinium over others considering its chemical and physical properties. Let us hence learn about the important basics of Gadolinium’s properties, applications and other interesting facts on the go.
A Quick Note of What Gadolinium is
The discovery of Gadolinium (The element’s symbol is Gd) dates back to 1880. The Swiss chemist ‘Jean Charles Galissard de Marignac’ found Gadolinium by using the method of spectroscopic line detection over the compound Gadolinia. Following which, the 1st isolation was a success in 1886, by the French chemist ‘Paul Émile Lecoq de Boisbaudran’ by separating this element Gadolinium from “Gadolinia ''.
In the absence of an oxidized state, Gadolinium is a silvery-white lanthanide metal, present in the 66th position of the f-block and the 6th row of the Periodic Table. The compound’s atomic number is 64. Nuclear reactors, radiography, electronic device production, metallurgy and many other applications can be listed for using Gadolinium in the areas of technology, arts and science, engineering, medicine, etc.
The Notable Physical Properties of Gadolinium
Solid structure at 20°C STP (Standard Conditions for Temperature and Pressure).
Position of Gadolinium in the Periodic Table is 66, f-Block, 6th row, put under the category of lanthanides.
Toxicity is said to be lower but triggers issues such as skin and eye irritation for human beings. No prominent effect over animals and plants due to Gadolinium.
Soft and silvery-white bright metal.
The element is named with its primary mineral, Gadolinite.
Gadolinium is both ductile and malleable.
[GAD-ə-LIN-ee-əm] is the pronunciation for Gadolinium.
The element is found in the earth’s crust at the range of 5.2 parts per million.
One of the rarely observed metals on the earth.
HCP (Hexagonal Close Packing) is the crystal structure.
Has good resistance to high-temperature conditions.
Has 13 naturally-derived isotopes and 27-synthetic isotopes.
Paramagnetic at room temperature and turns into a ferromagnetic substance at colder conditions (estimated to be above 20°C).
Gadolinium is a form of Primordial isotope.
When added together with sulfur, boron, selenium, nitrogen, carbon, arsenic, phosphorus, and silicon, the element Gadolinium will create binary compounds as a result of its chemical reaction.
Highest thermal stability is noted with the isotope 157 Gd.
Points Covering the Chemical Properties of Gadolinium
Molecular Weight of Gadolinium is 157.25 g/mol-1.
The atomic number is 64.
The count of electrons per each shell is 2, 8, 18, 25, 9, and 2.
Boiling point is 3273°C at 5923°F and 3546 K
7.90 is the Density (g / cm−3).
[Xe] 4f7 5d1 6s2 is the electronic configuration of Gadolinium.
Trivalent bond formation during its compound state.
Both the exact and monoisotopic mass value is 157.92411 g/mol.
The presence of 1 Heavy Atom counted.
Estimated Molar Heat Capacity is 37.03 J/(mol·K).
Highly reactive with other dilute acid forms.
There is 1 Covalently-Bonded Unit.
17°C is the estimated value for the Curie Point.
1313°C is the melting point of Gadolinium at 2395°F, 1586 K.
Gadolinium is a Canonicalized element.
Unreactive with oxygen but in the presence of moist air, the element will tarnish and create a layer of white oxide, which is gadolinium(III) oxide (Gd2O3), for restricting further oxidation.
Occurrence and Existence of Gadolinium and its Isotopes
154Gd, 155Gd, 156Gd, 157Gd, 158Gd, and 160Gd are the 6 major isotopes of Gadolinium. There are about 29 different radioactive isotopes for Gd, out of which, 152Gd is said to be the naturally-occurring isotope of Gd that possesses high stability. Note that the primary mode of decaying in Gadolinium is beta decay at conditions of higher atomic mass and the resulting product is an isotope of terbium.
Even though the exact measure of producing Gadolinium varies annually, it is anyhow estimated to be around 400 tonnes per year. The metal is not present in the natural environment owing to its high reactivity.
The lanthanide Gadolinium is noted to be found in specific mineral oxides such as bastnäsite and monazite. Even the mineral Gadolinite has only a sizable quantity of Gadolinium with it. ‘Lepersonnite-(Gd)’ is one of the key minerals known to be closely associated with Gadolinium and is extremely rare for existence.
India, Sri Lanka, the United States of America, China, and Brazil are some of the notable countries, where 1 million is the estimated exceed of reserved value for Gadolinium.
Real-Life Uses of Gadolinium with Examples
Video recorders and other electronic devices are produced by making use of the alloys of Gadolinium.
Gadolinium is used as a Dopant for producing fuel cells, as in the case of cerium oxide, which is one of the optimal and cost-effective methods.
In the case of a CANDU reactor type, the isotope 157Gd is useful to impact in conditions of emergency shutting-down of nuclear programmes. Moreover, the same element is preferred as a burnable poison for nuclear marine propulsion.
To imitate diamond stones and jewellery, workers tend to use the Gadolinium Gallium Garnet (GGG, Gd3Ga5O12).
Colour Television Gadgets prefer Gadolinium in the form of Phosphorus and even to manufacture microwave-related appliances. Similarly, this change is noted in the case of x-ray machines, where Gadolinium acts as suspension for a polymer matrix in the region of detection.
Since Gadolinium has good resistance to high temperatures, the lanthanide is used in the making of other high-temperature gadgets.
Targeting the tumour cells during a neutron therapy is possible from using the isotope 157Gd. This applies even to nuclear reactors and neutron radiography techniques.
Magnetic Resonance Imaging (MRI) makes use of Gadolinium Contrast, owing to its paramagnetic ions where it enhances the nuclear relaxation rates.
Conclusion
Gadolinium is a silver-white coloured lanthanide metal, with atomic number 64 and present in the f-block’s 66th position in the Periodic Table. The element was discovered by a Swiss Chemist in 1880 and was isolated by a French Chemist in 1886. Gadolinium denoted as Gd has multiple radioactive isotopes and a vast majority of them are not found in the natural atmosphere due to its high reactivity. This compound is a solid structure with HCP formation at STP and has high resistive power to extremely heated conditions. Domains such as electronic production, chemical oxidation, diamond imitation, nuclear power plants, fuel cell generation, are some of the common instances where Gadolinium is preferred at different stages of production and manufacturing.
FAQs on Gadolinium: Properties, Uses, and Significance
1. What is Gadolinium and where is it placed in the periodic table?
Gadolinium, with the symbol Gd and atomic number 64, is a silvery-white, rare-earth metal. In the periodic table, it belongs to the lanthanide series, which is a part of the f-block elements. It is positioned between Europium (Eu) and Terbium (Tb).
2. What are the key physical and chemical properties of Gadolinium?
Gadolinium is a malleable and ductile metal with several distinctive properties:
Appearance: It is a bright, silvery-white metal that is relatively stable in dry air but tarnishes in moist air.
Magnetic Properties: It is unique for being ferromagnetic at temperatures below its Curie point of 20 °C (293 K) and strongly paramagnetic above this temperature.
Reactivity: It reacts slowly with cold water and more quickly with hot water to form gadolinium hydroxide. It also dissolves in dilute acids.
Neutron Absorption: Gadolinium has the highest neutron-capture cross-section of all known elements, making it useful in nuclear applications.
3. How is Gadolinium typically extracted from its natural ores?
Gadolinium does not occur freely in nature but is found in several minerals like monazite and bastnäsite. The extraction is a multi-step process that involves crushing the minerals and treating them with acids to separate the rare-earth elements. Techniques like ion-exchange chromatography or solvent extraction are then used to separate Gadolinium from other lanthanides. Finally, pure Gadolinium metal is often obtained by reducing its anhydrous fluoride or chloride with calcium metal.
4. What are the most significant uses of Gadolinium in industry and medicine?
Gadolinium's unique properties make it valuable in several high-tech and medical fields:
Medical Imaging: Its most famous use is as a contrast agent in Magnetic Resonance Imaging (MRI) to improve the clarity of images.
Alloys: Adding as little as 1% Gadolinium can improve the workability and resistance to high temperatures and oxidation of iron and chromium alloys.
Nuclear Reactors: Due to its high neutron-absorption capacity, it is used in control rods of nuclear reactors to regulate nuclear fission.
Technology: It is used in making special magnets, electronic components, and as a green phosphor in colour television tubes.
5. Why is the Gadolinium(III) ion so effective as an MRI contrast agent?
The Gadolinium(III) ion, Gd³⁺, is highly effective for MRI scans because of its strong paramagnetic properties. The Gd³⁺ ion has seven unpaired electrons in its 4f orbital. This large number of unpaired electrons creates a strong local magnetic field that influences the surrounding water protons in the body. It shortens their relaxation time (specifically T1 relaxation), which significantly increases the signal intensity and creates a much clearer, brighter contrast between different types of tissues on the MRI image.
6. What are the health risks associated with Gadolinium-based contrast agents?
While generally safe, Gadolinium-based contrast agents (GBCAs) carry some risks. The free Gd³⁺ ion is toxic. To prevent this, it is bound to a large organic molecule called a chelating agent before being injected. For patients with severe kidney problems, there is a risk of a rare but serious condition called Nephrogenic Systemic Fibrosis (NSF), which causes thickening of the skin and connective tissues. In recent years, concerns have also been raised about trace amounts of gadolinium being retained in the body, particularly the brain, even in patients with normal kidney function.
7. How does the electronic configuration of Gadolinium, [Xe] 4f⁷ 5d¹ 6s², explain its chemical behaviour?
The electronic configuration of Gadolinium is key to its chemistry. When Gadolinium forms its most common ion, Gd³⁺, it loses the two 6s electrons and the single 5d electron. This leaves it with an electron configuration of [Xe] 4f⁷. The 4f orbital is exactly half-filled with seven electrons. A half-filled orbital represents a state of high stability and lower energy. This strong tendency to achieve a stable, half-filled f-orbital dictates why Gadolinium predominantly forms the +3 oxidation state in its compounds.
8. What is the 'Gadolinium break' and what is its significance in lanthanide chemistry?
The 'Gadolinium break' refers to a distinct irregularity or 'kink' in the trend of physical and chemical properties observed across the lanthanide series. While properties like ionic radii generally show a smooth decrease (lanthanide contraction), properties such as the stability constants of complexes show a dip or break at Gadolinium (Gd³⁺). This break occurs because of the unique electronic stability of the half-filled 4f⁷ configuration of Gd³⁺ and a possible change in the hydration number (the number of water molecules surrounding the ion) around this point in the series.
