Magnesium

Magnesium


 



Overview
Physical and chemical properties
Isotopes
Creation
Applications ( as metal )
Applications of magnesium compounds
Popular reactions

Overview
Magnesium is a chemical element with symbol Mg and atomic number 12.
And electronic configuration is 1S² 2S²2P⁶ 3S².
Its common oxidation number is +2.
It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole.
Magnesium is the fourth most common element in the Earth as a whole (behind iron, oxygen and silicon), making up 13% of the planet's mass and a large fraction of the planet's mantle.
The relative abundance of magnesium is related to the fact that it is easily built up in supernova stars from a sequential addition of three helium nuclei to carbon (which in turn is made from three helium nuclei).
Due to magnesium ion's high solubility in water, it is the third most abundant element dissolved in seawater.( mainly as MgCl2 )

The free element (metal) is not found naturally on Earth, as it is highly reactive (though once produced, it is coated in a thin layer of oxide, which partly masks this reactivity).
The free metal burns with a characteristic brilliant white light, making it a useful ingredient in flares.
 
The metal is now mainly obtained by electrolysis of magnesium salts obtained from brine.

Commercially, the chief use for the metal is as an alloying agent to make aluminium-magnesium alloys,

sometimes called "magnalium" or "magnelium". Since magnesium is less dense than aluminium, these alloys are prized for their relative lightness and strength.

In human biology, magnesium is the eleventh most abundant element by mass in the human body; its ions are essential to all living cells, where they play a major role in manipulating important biological polyphosphate compounds like ATP, DNA, and RNA.
Hundreds of enzymes thus require magnesium ions to function.
Magnesium compounds are used medicinally as common laxatives, antacids (e.g., milk of magnesia),
and in a number of situations where stabilization of abnormal nerve excitation and blood vessel spasm is required (e.g., to treat eclampsia). Magnesium ions are sour to the taste, and in low concentrations they help to impart a natural tartness to fresh mineral waters.



Physical and chemical properties
Elemental magnesium is a

•     fairly strong,
•     silvery-white,
•     light-weight metal (two thirds the density of aluminium).

It tarnishes slightly when exposed to air, although unlike the alkali metals, an oxygen-free environment is unnecessary for storage because magnesium is protected by a thin layer of oxide that is fairly impermeable and difficult to remove.
Like its lower periodic table group neighbor calcium, magnesium reacts with water at room temperature, though it reacts much more slowly than calcium.
When submerged in water, hydrogen bubbles will almost unnoticeably begin to form on the surface of the metal, though if powdered it will react much more rapidly.
The reaction will occur faster with higher temperatures.
Magnesium's ability to react with water can be harnessed to produce energy and run a magnesium-based engine.
Magnesium also reacts exothermically with most acids, such as hydrochloric acid (HCl).
As with aluminium, zinc and many other metals, the reaction with hydrochloric acid produces the chloride of the metal and releases hydrogen gas.


Magnesium is a highly flammable metal, but while it is easy to ignite when powdered or shaved into thin strips, it is difficult to ignite in mass or bulk. Once ignited, it is difficult to extinguish,
being able to burn in nitrogen (forming magnesium nitride),
Mg_(s) + N2_(g)  → Mg₃N_2(s)
carbon dioxide (forming magnesium oxide and carbon)
Mg_(s) + CO_2(g)  → MgO_(s) + C_(s)
and water (forming magnesium oxide and hydrogen).
Mg_(s) + H₂O_{(g / l )}  → MgO_(s) + H_2(g)
This property was used in incendiary weapons used in the firebombing of cities in World War II, the only practical civil defense being to smother a burning flare under dry sand to exclude the atmosphere.
On burning in air, magnesium produces a brilliant white light which includes strong ultraviolet.
Thus magnesium powder (flash powder) was used as a source of illumination in the early days of photography.
Later, magnesium ribbon was used in electrically ignited flash bulbs. Magnesium powder is used in the manufacture of fireworks and marine flares where a brilliant white light is required.
Flame temperatures of magnesium and magnesium alloys can reach 3,100 °C (3,370 K; 5,610 °F)(note:°C=5/9 x ( °F - 32 )  and °C = K - 273.15 ), although flame height above the burning metal is usually less than 300 mm (12 in).[8] Magnesium may be used as an ignition source for thermite, an otherwise difficult to ignite mixture of aluminium and iron oxide powder.
Magnesium compounds are typically white crystals.
Most are soluble in water, providing the sour-tasting magnesium ion Mg2+. Small amounts of dissolved magnesium ion contribute to the tartness and taste of natural waters. ( you will learn about it more in a later section under "water" , or you can use the navigation page to navigate through,,here I am not entering those things in hope of not to make this ugly )
Magnesium ion in large amounts is an ionic laxative, and magnesium sulfate (common name: Epsom salt) is sometimes used for this purpose.
So-called "milk of magnesia" is a water suspension of one of the few insoluble magnesium compounds, magnesium hydroxide.
The undissolved particles give rise to its appearance and name.
Milk of magnesia is a mild base commonly used as an antacid, which has some laxative side effect.


Isotopes
Magnesium has three stable isotopes:
    ²⁴Mg    78.99%    12 neutrons
    ²⁵Mg    10.00%     13 neutrons
    ²⁶Mg    11.01%     14 neutrons
All are present in significant amounts.
About 79% of Mg is ²⁴Mg.
The isotope 28Mg is radioactive and in the 1950s to 1970s was made commercially by several nuclear power plants for use in scientific experiments. This isotope has a relatively short half-life (21 hours) and so its use was limited by shipping times.
26Mg has found application in isotopic geology, similar to that of aluminium. 26Mg is a radiogenic daughter product of ²⁶Al, which has a half-life of 717,000 years. Large enrichments of stable ²⁶Mg have been observed in the Ca-Al-rich inclusions of some carbonaceous chondrite meteorites. The anomalous abundance of ²⁶Mg is attributed to the decay of its parent ²⁶Al in the inclusions. Therefore, the meteorite must have formed in the solar nebula before the ²⁶Al had decayed. Hence, these fragments are among the oldest objects in the solar system and have preserved information about its early history.
It is conventional to plot ²⁶Mg/²⁴Mg against an Al/Mg ratio. In an isochron dating plot, the Al/Mg ratio plotted is²⁷Al/²⁴Mg. The slope of the isochron has no age significance, but indicates the initial ²⁶Al/²⁷Al ratio in the sample at the time when the systems were separated from a common reservoir.
( Most of the theories related to half-life goes under the subject "PHYSICS"
Any how under these tutorials I have described it simply use navigation page )

Creation 
(note:Magnesium is produced in stars larger than 3 solar masses by fusing helium and neon in the alpha process at temperatures above 600 megakelvins.)

Although magnesium is found in over 60 minerals, only

•     dolomite,
•     magnesite,
•     brucite [ Mg(OH)₂ ],
•     carnallite,
•     talc, and
•     olivine

are of commercial importance.

The Mg2+ cation is the second most abundant cation in seawater (occurring at about 12% of the mass of sodium there), which makes seawater and sea-salt an attractive commercial source of Mg.
To extract the magnesium, calcium hydroxide is added to seawater to form magnesium hydroxide precipitate.

    MgCl₂ + Ca(OH)₂ → Mg(OH)₂ + CaCl₂

Magnesium hydroxide (brucite) is insoluble in water so it can be filtered out, and reacted with hydrochloric acid to obtain concentrated magnesium chloride.

    Mg(OH)₂ + 2 HCl → MgCl₂ + 2 H₂O

From magnesium chloride, electrolysis produces magnesium.

In the United States, magnesium is principally obtained by electrolysis of fused magnesium chloride from brines, wells, and sea water.

At the cathode, the Mg²⁺ ion is reduced by two electrons to magnesium metal:

    Mg²⁺ + 2 e⁻ → Mg

At the anode, each pair of Cl⁻ ions is oxidized to chlorine gas, releasing two electrons to complete the circuit:

    2 Cl⁻ → Cl_{2 (g)} + 2 e⁻

The United States has traditionally been the major world supplier of this metal, supplying 45% of world production even as recently as 1995.
Today, the US market share is at 7%, with a single domestic producer left, US Magnesium, a Renco Group company in Utah born from now-defunct Magcorp.

As of 2005, China has taken over as the dominant supplier, pegged at 60% world market share, which increased from 4% in 1995. Unlike the above-described electrolytic process, China is almost completely reliant on a different method of obtaining the metal from its ores, the silicothermic Pidgeon process (the reduction of the oxide at high temperatures with silicon).
( It will be enough for you to know about the above process )





Applications ( as metal )
Magnesium is the third most commonly used structural metal, following iron and aluminium. It has been called the lightest useful metal by The Periodic Table of Videos.

The main applications of magnesium are, in order:

•     component of aluminium alloys,
•     in die-casting (alloyed with zinc),
•     to remove sulfur in the production of iron and steel,
•     the production of titanium in the Kroll process.

Magnesium, in its purest form, can be compared with aluminium, and is strong and light, so it is used in several high volume part manufacturing applications, including automotive and truck components.
Specialty, high-grade car wheels of magnesium alloy are called "mag wheels", although the term is often more broadly misapplied to include aluminium wheels.

"The high magnesium content used for the crankcase of the late-World War II Wright Duplex Cyclone eighteen-cylinder radial aviation engine was a serious problem for the earliest examples of the Boeing B-29 heavy bomber, as engine fires in flight could set the engine crankcases alight, literally "torching" the wing spar apart in under a minute causing wing failure."

The second application field of magnesium is electronic devices.
Because of :

•     low weight,
•     good mechanical and electrical properties,

magnesium is widely used for manufacturing of mobile phones, laptop and tablet computers, cameras, and other electronic components.

Historically, magnesium was one of the main aerospace construction metals and was used for German military aircraft as early as World War I and extensively for German aircraft in World War II.

The Germans coined the name 'Elektron' for magnesium alloy. The term is still used today.
The application of magnesium in the commercial aerospace industry was generally restricted to engine related components, due either to perceived hazards with magnesium parts in the event of fire, or corrosion.
Currently the use of magnesium alloys in aerospace is increasing, mostly driven by the increasing importance of fuel economy and the need to reduce weight.
The development and testing of new magnesium alloys continues, notably Elektron 21, which has successfully undergone extensive aerospace testing for suitability in engine, internal and airframe components.
The European Community runs three R&D magnesium projects in the Aerospace priority of Six Framework Program.


Niche uses of the metal

Magnesium, being readily available and relatively nontoxic, has a variety of uses:

• Magnesium is flammable, burning at a temperature of approximately 3,100 °C (3,370 K; 5,610 °F), and the autoignition temperature of magnesium ribbon is approximately 473 °C (746 K; 883 °F).It produces intense, bright, white light when it burns. Magnesium's high burning temperature makes it a useful tool for starting emergency fires during outdoor recreation. Other uses include flash photography, flares, pyrotechnics and fireworks sparklers. Magnesium is also often used to ignite thermite, or other materials that require a high ignition temperature.

• In the form of turnings or ribbons, to prepare Grignard reagents, which are useful in organic synthesis.

• As an additive agent in conventional propellants and the production of nodular graphite in cast iron.

• As a reducing agent for the production of uranium and other metals from their salts.

• As a sacrificial (galvanic) anode to protect underground tanks, pipelines, buried structures, and water heaters.

• As a metal, this element's principal use is as an alloying additive to aluminium with these aluminium-magnesium alloys being used mainly for beverage cans.

Applications of magnesium compounds

• Magnesium compounds, primarily magnesium oxide (MgO), are used as a refractory material in furnace linings for producing iron, steel, nonferrous metals, glass and cement. Magnesium oxide and other magnesium compounds are also used in the agricultural, chemical, and construction industries.

• Magnesium reacted with an alkyl halide gives a Grignard reagent ( you will learn more under organic chemistry ), which is a very useful tool for preparing alcohols.

Popular reactions

 Mg_(s) + HOT H₂O_(l) → Mg(OH)_2(s) + H_2(g)
 Mg_(s) +H₂O_(g) → MgO_(s) + H_2(g)
 Mg_(s) + O_2(g)→ MgO_(s)
 Mg_(s) + N_2(g)→ Mg₃N_2(s)
 Mg_(s) + CO_2(g)→ MgO_(s) + C_(s)
 Mg_(s) + HCl_(aq)→ MgCl_2(aq) + H_2(g)
 Mg_(s) + H₂SO_4(aq)→ MgSO_4(aq) + H_2(g)
{ Whenever reacts with an acid [ for example an acid called HX ] it produces the salt of Mg2+ and H2 gas.As bellow:
 Mg_(s) + HX_(aq) → Mg(X)_2(aq) + H_2(g)
}

 Mg_(s) + HNO_{3( aq / conc )} → Mg(NO₃)_2(aq) + NO_2(g) + H₂O_(l)
{ But it is different when reacts with Nitric(V) acid because of it's high action it can oxidate H2_(g) to H₂O_(l) }

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