Magnesium is a chemical aspect with the image Mg and atomic quantity 12. It’s a shiny grey strong which bears an in depth bodily resemblance to the opposite 5 components within the second column (group 2, or alkaline earth metals) of the periodic desk: all group 2 components have the identical electron configuration within the outer electron shell and an identical crystal construction.
Magnesium is produced in massive, getting old stars from the sequential addition of three helium nuclei to a carbon nucleus. When such stars explode as supernovas, a lot of the magnesium is expelled into the interstellar medium the place it could recycle into new star techniques. Magnesium is the eighth most plentiful aspect within the Earth’s crust[9] and the fourth most typical aspect within the Earth (after iron, oxygen and silicon), making up 13% of the planet’s mass and a big fraction of the planet’s mantle. It’s the third most plentiful aspect dissolved in seawater, after sodium and chlorine.[10]
Magnesium happens naturally solely together with different components, the place it invariably has a +2 oxidation state. The free aspect (steel) could be produced artificially, and is very reactive (although within the environment it’s quickly coated in a skinny layer of oxide that partly inhibits reactivity – see passivation). The free steel burns with a attribute brilliant-white mild. The steel is now obtained primarily by electrolysis of magnesium salts obtained from brine, and is used primarily as a part in aluminium-magnesium alloys, generally referred to as magnalium or magnelium. Magnesium is much less dense than aluminium, and the alloy is prized for its mixture of lightness and energy.
Magnesium is the eleventh most plentiful aspect by mass within the human physique and is important to all cells and a few 300 enzymes.[11] Magnesium ions work together with polyphosphate compounds resembling ATP, DNA, and RNA. A whole bunch of enzymes require magnesium ions to operate. Magnesium compounds are used medicinally as frequent laxatives, antacids (e.g., milk of magnesia), and to stabilize irregular nerve excitation or blood vessel spasm in such situations as eclampsia.[11]
Contents
Traits
Elemental magnesium is a gray-white light-weight steel, two-thirds the density of aluminium. Magnesium has the bottom melting (923 Okay (1,202 °F)) and the bottom boiling level 1,363 Okay (1,994 °F) of all of the alkaline earth metals.
Pure polycrystalline magnesium is brittle and simply fractures alongside shear bands. It turns into rather more ductile when alloyed with small quantity of different metals, resembling 1% aluminium.[12] Ductility of polycrystalline magnesium will also be considerably improved by decreasing its grain dimension to ca. 1 micron or much less.[13]
Chemical properties
Basic chemistry
It tarnishes barely when uncovered to air, though, in contrast to the heavier alkaline earth metals, an oxygen-free setting is pointless for storage as a result of magnesium is protected by a skinny layer of oxide that’s pretty impermeable and tough to take away.
Magnesium reacts with water at room temperature, although it reacts rather more slowly than calcium, an identical group 2 steel. When submerged in water, hydrogen bubbles kind slowly on the floor of the steel – although, if powdered, it reacts rather more quickly. The response happens sooner with greater temperatures (see security precautions). Magnesium’s reversible response with water could be harnessed to retailer power and run a magnesium-based engine. Magnesium additionally reacts exothermically with most acids resembling hydrochloric acid (HCl), producing the steel chloride and hydrogen fuel, much like the HCl response with aluminium, zinc, and lots of different metals.
Flammability
Magnesium is very flammable, particularly when powdered or shaved into skinny strips, although it’s tough to ignite in mass or bulk. Flame temperatures of magnesium and magnesium alloys can attain 3,100 °C (5,610 °F),[14] though flame top above the burning steel is normally lower than 300 mm (12 in).[15] As soon as ignited, such fires are tough to extinguish, as a result of combustion continues in nitrogen (forming magnesium nitride), carbon dioxide (forming magnesium oxide and carbon), and water (forming magnesium oxide and hydrogen, which additionally combusts because of warmth within the presence of extra oxygen). This property was utilized in incendiary weapons throughout the firebombing of cities in World Struggle II, the place the one sensible civil protection was to smother a burning flare beneath dry sand to exclude environment from the combustion.
Magnesium may additionally be used as an igniter for thermite, a mix of aluminium and iron oxide powder that ignites solely at a really excessive temperature.
Natural chemistry
Organomagnesium compounds are widespread in natural chemistry. They’re generally discovered as Grignard reagents. Magnesium can react with haloalkanes to present Grignard reagents. Examples of Grignard reagents are phenylmagnesium bromide and ethylmagnesium bromide. The Grignard reagents operate as a typical nucleophile, attacking the electrophilic group such because the carbon atom that’s current inside the polar bond of a carbonyl group.
A distinguished organomagnesium reagent past Grignard reagents is magnesium anthracene with magnesium forming a 1,4-bridge over the central ring. It’s used as a supply of extremely lively magnesium. The associated butadiene-magnesium adduct serves as a supply for the butadiene dianion.
Supply of sunshine
When burning in air, magnesium produces a brilliant-white mild that features robust ultraviolet wavelengths. Magnesium powder (flash powder) was used for topic illumination within the early days of pictures.[16][17] Later, magnesium filament was utilized in electrically ignited single-use pictures flashbulbs. Magnesium powder is utilized in fireworks and marine flares the place an excellent white mild is required. It was additionally used for numerous theatrical results,[18] resembling lightning,[19] pistol flashes,[20] and supernatural appearances.[21]
Incidence
Magnesium is the eighth-most-abundant aspect within the Earth’s crust by mass and tied in seventh place with iron in molarity.[9] It’s present in massive deposits of magnesite, dolomite, and different minerals, and in mineral waters, the place magnesium ion is soluble.
Though magnesium is discovered in additional than 60 minerals, solely dolomite, magnesite, brucite, carnallite, talc, and olivine are of economic significance.
The Mg2+ cation is the second-most-abundant cation in seawater (about ⅛ the mass of sodium ions in a given pattern), which makes seawater and sea salt engaging business sources for Mg. To extract the magnesium, calcium hydroxide is added to seawater to kind magnesium hydroxide precipitate.
Magnesium hydroxide (brucite) is insoluble in water and could be filtered out and reacted with hydrochloric acid to produced concentrated magnesium chloride.
From magnesium chloride, electrolysis produces magnesium.
Varieties
Alloys
As of 2013, magnesium alloys consumption was lower than a million tonnes per yr, in contrast with 50 million tonnes of aluminum alloys. Their use has been traditionally restricted by the tendency of Mg alloys to corrode, creep at excessive temperatures, and combust.[22]
Corrosion
The presence of iron, nickel, copper, and cobalt strongly prompts corrosion. In additional than hint quantities, these metals precipitate as intermetallic compounds, and the precipitate locales operate as lively cathodic websites that cut back water, inflicting the lack of magnesium.[22] Controlling the amount of those metals improves corrosion resistance. Ample manganese overcomes the corrosive results of iron. This requires exact management over composition, growing prices.[22] Including a cathodic poison captures atomic hydrogen inside the construction of a steel. This prevents the formation of free hydrogen fuel, a necessary issue of corrosive chemical processes. The addition of about one in 300 elements arsenic reduces its corrosion price in a salt resolution by an element of practically ten.[22][23]
Excessive-temperature creep and flammability
Analysis confirmed that magnesium’s tendency to creep at excessive temperatures is eradicated by the addition of scandium and gadolinium. Flammability is tremendously lowered by a small quantity of calcium within the alloy.[22] Latest analysis has indicated that through the use of rare-earth components, it could be doable to fabricate magnesium alloys with an ignition temperature greater than magnesium’s liquidus and in some circumstances doubtlessly pushing it near magnesium’s boiling level.[24]
Compounds
Magnesium varieties quite a lot of compounds vital to trade and biology, together with magnesium carbonate, magnesium chloride, magnesium citrate, magnesium hydroxide (milk of magnesia), magnesium oxide, magnesium sulfate, and magnesium sulfate heptahydrate (Epsom salts).
Isotopes
Magnesium has three steady isotopes: 24Mg, 25Mg and 26Mg. All are current in vital quantities (see desk of isotopes above). About 79% of Mg is 24Mg. The isotope 28Mg is radioactive and within the Fifties to Seventies was produced by a number of nuclear energy vegetation to be used in scientific experiments. This isotope has a comparatively brief half-life (21 hours) and its use was restricted by transport occasions.
The nuclide 26Mg has discovered software in isotopic geology, much like that of aluminium. 26Mg is a radiogenic daughter product of 26Al, which has a half-life of 717,000 years. Extreme portions of steady 26Mg have been noticed within the Ca-Al-rich inclusions of some carbonaceous chondrite meteorites. This anomalous abundance is attributed to the decay of its mother or father 26Al within the inclusions, and researchers conclude that such meteorites had been shaped within the photo voltaic nebula earlier than the 26Al had decayed. These are among the many oldest objects within the photo voltaic system and comprise preserved details about its early historical past.
It’s standard to plot 26Mg/24Mg in opposition to an Al/Mg ratio. In an isochron relationship plot, the Al/Mg ratio plotted is27Al/24Mg. The slope of the isochron has no age significance, however signifies the preliminary 26Al/27Al ratio within the pattern on the time when the techniques had been separated from a typical reservoir.
Manufacturing
World manufacturing was roughly 1,100 kt in 2017, with the majority being produced in China (930 kt) and Russia (60 kt).[25] China is nearly fully reliant on the silicothermic Pidgeon course of (the discount of the oxide at excessive temperatures with silicon, usually supplied by a ferrosilicon alloy through which the iron is however a spectator within the reactions) to acquire the steel.[26] The method will also be carried out with carbon at approx 2300 °C:
In the USA, magnesium is obtained principally with the Dow course of, by electrolysis of fused magnesium chloride from brine and sea water. A saline resolution containing Mg2+ ions is first handled with lime (calcium oxide) and the precipitated magnesium hydroxide is collected:
The hydroxide is then transformed to a partial hydrate of magnesium chloride by treating the hydroxide with hydrochloric acid and heating of the product:
The salt is then electrolyzed within the molten state. On the cathode, the Mg2+ ion is lowered by two electrons to magnesium steel:
On the anode, every pair of Cl− ions is oxidized to chlorine fuel, releasing two electrons to finish the circuit:
A brand new course of, strong oxide membrane expertise, entails the electrolytic discount of MgO. On the cathode, Mg2+ ion is lowered by two electrons to magnesium steel. The electrolyte is yttria-stabilized zirconia (YSZ). The anode is a liquid steel. On the YSZ/liquid steel anode O2− is oxidized. A layer of graphite borders the liquid steel anode, and at this interface carbon and oxygen react to kind carbon monoxide. When silver is used because the liquid steel anode, there is no such thing as a reductant carbon or hydrogen wanted, and solely oxygen fuel is advanced on the anode.[27] It has been reported that this technique gives a 40% discount in price per pound over the electrolytic discount technique.[28] This technique is extra environmentally sound than others as a result of there’s a lot much less carbon dioxide emitted.
The USA has historically been the key world provider of this steel, supplying 45% of world manufacturing at the same time as not too long ago as 1995. Immediately, the US market share is at 7%, with a single home producer left, US Magnesium, a Renco Group firm in Utah born from now-defunct Magcorp.[29]
Historical past – “is magnesium a metal or nonmetal”
The identify magnesium originates from the Greek phrase for areas associated to the tribe of the Magnetes, both a district in Thessaly referred to as Magnesia[30] or Magnesia advert Sipylum, now in Turkey.[31] It’s associated to magnetite and manganese, which additionally originated from this space, and required differentiation as separate substances. See manganese for this historical past.
In 1618, a farmer at Epsom in England tried to present his cows water from a properly there. The cows refused to drink due to the water’s bitter style, however the farmer observed that the water appeared to heal scratches and rashes. The substance turned referred to as Epsom salts and its fame unfold.[32] It was finally acknowledged as hydrated magnesium sulfate, MgSO4·7 H2O.
The steel itself was first remoted by Sir Humphry Davy in England in 1808. He used electrolysis on a mix of magnesia and mercuric oxide.[33] Antoine Bussy ready it in coherent kind in 1831. Davy’s first suggestion for a reputation was magnium,[33] however the identify magnesium is now used.
Makes use of as a steel
Magnesium is the third-most-commonly-used structural steel, following iron and aluminium.[34] The principle functions of magnesium are, so as: aluminium alloys, die-casting (alloyed with zinc),[35] eradicating sulfur within the manufacturing of iron and metal, and the manufacturing of titanium within the Kroll course of.[36] Magnesium is utilized in super-strong, light-weight supplies and alloys. For instance, when infused with silicon carbide nanoparticles, it has extraordinarily excessive particular energy.[37]
Traditionally, magnesium was one of many primary aerospace development metals and was used for German army plane as early as World Struggle I and extensively for German plane in World Struggle II. The Germans coined the identify “Elektron” for magnesium alloy, a time period which remains to be used right this moment. Within the business aerospace trade, magnesium was typically restricted to engine-related parts, because of fireplace and corrosion hazards. At the moment, magnesium alloy use in aerospace is growing, pushed by the significance of gasoline financial system.[38] Improvement and testing of recent magnesium alloys continues, notably Elektron 21, which (in check) has proved appropriate for aerospace engine, inner, and airframe parts.[39] The European Group runs three R&D magnesium tasks within the Aerospace precedence of Six Framework Program. Latest developments in metallurgy and manufacturing have allowed for the potential for magnesium alloys to behave as replacements for aluminium and metal alloys in sure functions.[40][41]
Within the type of skinny ribbons, magnesium is used to purify solvents; for instance, making ready super-dry ethanol.
Plane
Automotive
Each AJ62A and AE44 are latest developments in high-temperature low-creep magnesium alloys. The overall technique for such alloys is to kind intermetallic precipitates on the grain boundaries, for instance by including mischmetal or calcium.[46] New alloy improvement and decrease prices that make magnesium aggressive with aluminium will improve the variety of automotive functions.
Electronics
Due to low density and good mechanical and electrical properties, magnesium is extensively used for manufacturing of cell phones, laptop computer and pill computer systems, cameras, and different digital parts.
Different
Magnesium, being available and comparatively unhazardous, has quite a lot of makes use of:
Security precautions
Magnesium steel and its alloys could be explosive hazards; they’re extremely flammable of their pure kind when molten or in powder or ribbon kind. Burning or molten magnesium reacts violently with water. When working with powdered magnesium, security glasses with eye safety and UV filters (resembling welders use) are employed as a result of burning magnesium produces ultraviolet mild that may completely harm the retina of a human eye.[49]
Magnesium is able to decreasing water and releasing extremely flammable hydrogen fuel:[50]
Subsequently, water can’t extinguish magnesium fires. The hydrogen fuel produced intensifies the hearth. Dry sand is an efficient smothering agent, however solely on comparatively stage and flat surfaces.
Magnesium reacts with carbon dioxide exothermically to kind magnesium oxide and carbon:[51]
Therefore, carbon dioxide fuels slightly than extinguishes magnesium fires.
Burning magnesium could be quenched through the use of a Class D dry chemical fireplace extinguisher, or by overlaying the hearth with sand or magnesium foundry flux to take away its air supply.[52]
Helpful compounds
Magnesium compounds, primarily magnesium oxide (MgO), are used as a refractory materials in furnace linings for producing iron, metal, nonferrous metals, glass, and cement. Magnesium oxide and different magnesium compounds are additionally used within the agricultural, chemical, and development industries. Magnesium oxide from calcination is used as {an electrical} insulator in fire-resistant cables.[53]
Magnesium hydride is beneath investigation as a solution to retailer hydrogen.
Magnesium reacted with an alkyl halide offers a Grignard reagent, which is a really useful gizmo for making ready alcohols.
Magnesium salts are included in numerous meals, fertilizers (magnesium is a part of chlorophyll), and microbe tradition media.
Magnesium sulfite is used within the manufacture of paper (sulfite course of).
Magnesium phosphate is used to fireproof wooden utilized in development.
Magnesium hexafluorosilicate is used for moth-proofing textiles.