The Element Magnesium
Magnesium, atomic symbol Mg, is an element that belongs to group 2a of the periodic table. It is a shiny, silvery colored metal that is both strong and lightweight. In fact, it is the lightest metallic element to exist. All of this sounds pretty magnificent to me.
Cool Facts About Magnesium
- Magnesium, Mg, is the eighth-most abundant element.
- Magnesium oxide is the second most abundant compound found in the earth’s crust.
- For every cubic kilometer of seawater, there are about 1.3 billion kilograms of magnesium.
- Magnesium is the most lightweight out of all the metallic elements.
- Magnesium’s name comes from Magnesia, a region of Greece. The mineral magnesia alba was first discovered at this location.
- A magnesium fire is very difficult to put out, and cannot be extinguished by water
Magnesium on the Periodic Table
Magnesium, symbol Mg, has atomic number 12 on the periodic table. It is an alkaline earth metal in group 2, sitting below beryllium, above calcium, and to the right of sodium. It has a low electronegativity of 1.31, and the magnesium atom has an electron configuration of [Ne] 3s2 or 1s2 2s2 2p6 3s2
Magnesium’s Abundance in Nature
Magnesium is the third most abundant structural metal in the Earth’s crust and is very easy to find in the environment. Not only does it occur in sixty different minerals, but can also be found in seawater and underground. However, it is not found free in nature. To obtain pure magnesium metal, it must be processed, which will be discussed later on.
The element magnesium is produced in large, aging stars from the addition of three helium nuclei to a carbon nucleus. When supernovas explode, they expell magenesium into space where it may become part of new star systems.
Health Effects of Magnesium
Magnesium mineral is crucial to humans and is necessary for the body to function properly. It plays a role in muscle movement, bone strength, blood sugar levels, and cardiovascular health. Adults have about 25 grams of stored magnesium and should intake about 300 to 400 mg daily. Achieving the ideal intake can be easy with a diet filled with magnesium-rich foods, including whole grains, nuts, seeds, and green leafy vegetables.
Magnesium’s Applications in Today’s World
Similar to titanium, magnesium has a high strength-to-weight ratio. This makes magnesium a favorable choice for products that must be lightweight. These include aircraft, car engines, and missiles. Explosive and pyrotechnic devices contain magnesium often times. The element produces an extremely bright white light when burned in the air.
Magnesium compounds are used for refractory material, which is designed to withstand extremely high temperatures. Refractory material lines furnaces that are used to produce metals, glass, and cement.
Magnesium, while abundant, is a costly metal. To save money, it is often combined with aluminum in an alloy. The two make a good team because they are both lightweight metals with many structural applications. However, they also have their differences. Aluminum is a much cheaper alternative to magnesium. It is more stable and has more strength. But, magnesium is more lightweight. Magnesium alloys are also easier to produce, in the sense that they solidify in a quicker time. On the other hand, magnesium is highly reactive and requires a protective coating to prevent corrosion. Additionally, it is softer than aluminum, which is not ideal for industrial uses. When put together in an alloy, the two metals work by combining their strengths to produce a much more effective alloy.
History of Magnesium
Who discovered Magnesium?
Prior to 1755, no one knew the difference between magnesium and calcium. The two elements were believed to be the same element. A Scottish chemist named Joseph Black conducted an experiment to distinguish the two elements from each other. A few years later in 1808, Sir Humphrey Davy (who also plays a role in the discovery of boron and iodine) was able to isolate the magnesium element by taking a magnesium-mercury amalgam and evaporating the element from it.
To go into more detail, he built a large battery that would function to conduct electricity through a salt, which would be the magnesium amalgam. A paste out of moist magnesium oxide and red mercury oxide created the amalgam. Davy then created a little well in the paste and added mercury metal to act as a negative electrode (and platinum as a positive electrode). Then, using the battery, he conducted electricity through the paste to form the amalgam. Lastly, the amalgam was heated and elemental magnesium was able to be separated.
Solid magnesium metal is protected by a layer of natural oxide. Although thin, this layer prevents the metal from reacting with air. Why do we want to protect magnesium from the air? Magnesium metal burns when exposed to air. It will then react with oxygen by producing a brilliant white flame, forming magnesium oxide.
Magnesium is more reactive than transition metals or rare-earth elements like molybdenum or erbium. It reacts slowly with hot water and quickly with steam to form magnesium hydroxide and magnesium oxide respectively.
Magnesium in Organic Chemistry
Those that have taken Organic Chemistry are likely to be familiar with the Grignard reagent. The Grignard reagent is the product of magnesium reacting with an alkyl or alkenyl halide. It is a strong nucleophile and base that reacts with protic compounds (protic means protons). Grignard reactions are important in organic chemistry because it results in a carbon-carbon bond, which is used to synthesize different alcohols.
There are a plethora of magnesium compounds that are widespread in nature. Several of them have important commercial use, while others can be used in the laboratory.
When you burn a strip of magnesium ribbon, it produces an extremely bright white light, AND leaves behind a white powder. The white powder is mostly composed of magnesium oxide, MgO.
Check out how bright magnesium ribbon is when heated, from the Chemistry Demo Lab Ohio State University:
Magnesium oxide, a naturally occurring mineral, is a white, thermally stable powder. Magnesium and oxygen ions combine in a strong ionic bond, making it insoluble in water. Its high melting point of 2851.85˚C (5165.33˚F) and chemical stability makes it important in the refractory industry. It is in furnace linings, crucibles, and is a common fireproofing ingredient. Magnesium oxide is basic, making it useful in the medical field as well. Mag-Caps and Mag-Ox 400 are magnesium oxide containing medications that act to treat heartburn and upset stomachs by neutralizing excess acid. Students also rely on magnesium oxide when they read their textbooks or write down their notes- magnesium oxide treats paper. Without magnesium oxide, the paper would rot because of its acidity.
Magnesium peroxide, MgO2
Magnesium peroxide, MgO2, is the product of magnesium oxide combining with hydrogen peroxide in an exothermic reaction. It comes in the form of an odorless, off-white powder. Upon breaking down, it will release oxygen, making it useful in agriculture and for water treatment. It “fixes” damaged soil by correcting magnesium deficiencies and by acting as a source of oxygen. Magnesium peroxide will treat water by regulating the pH level and reducing contaminants.
When magnesium oxide combines with water, it forms magnesium hydroxide, Mg(OH)2. Vice-versa, upon heating, magnesium hydroxide loses moisture and turns back to magnesium oxide. Magnesium hydroxide is an inorganic compound that either occurs in nature as a brucite mineral or through the precipitation of seawater. It is insoluble in water and holds antacid and laxative properties. When suspended in water or alkaline solution, magnesium hydroxide forms ‘milk of magnesia’. This acid-neutralizing agent is well known for its osmotic-type laxative and antacid properties. Milk of magnesia’s mechanism of action works by drawing hydroxide ions into the stomach, which will mediate stomach acid and retain water in the intestines.
Magnesium Sulfide & Sulfate
Magnesium sulfate, MgSO4, is a sulfate-containing salt and metal sulfate. This colorless, crystalline solid is the product of magnesium hydroxide mixing with sulfur dioxide and oxygen. It has many uses in medicine: It is an anticonvulsant, calcium channel blocker, anesthesia, tocolytic agent, anti-arrhythmic drug, and analgesic. Magnesium sulfate is also useful in the industrial field, where it is added to cement and fertilizers. It can even make homemade lawn food. There are several forms of magnesium sulfate hydrates, including the anhydrous, MgSO4, and heptahydrate, MgSO4· 7H2O crystals.
Magnesium sulfate is the most soluble when it is in its anhydrous form. It is obtained when hexahydrate magnesium sulfate crystals are heated to a temperature of around 300˚C (572˚F). It is common in science laboratories, as it is a drying agent. When exposed to moisture, magnesium sulfate crystals will soak up the water and clump together. Filtration removes the clump.
After a hard workout, you may find yourself suffering from sore, achy muscles. A common way people alleviate this pain is by soaking in an Epsom salt bath. Epsom salt is the synthetically prepared heptahydrate compound of magnesium sulfate. It looks identical to table salt, except that it is larger and more coarse. However, do not use it to season your food. Ingesting too much of the chemical can have serious consequences, including cardiac arrest and bradyarrhythmia. In water, the salt dissociates into magnesium and sulfate ions, which *supposedly soaks through your skin during baths. This helps cure sore muscles by increasing magnesium levels in the blood.
*Studies have shown varying results for how effective Epsom salt baths actually are for alleviating muscle pain.
Magnesium carbonate, MgCO3 occurs in nature as magnesite. Magnesite is a yellowish-gray, or brown, crystalline ore that is resistant to very hot temperatures. Magnesium carbonate is also the product of magnesium hydroxide absorbing carbon dioxide and water. Magnesium carbonate is an inorganic, basic, insoluble, and hydrated compound. It comes as a lightweight, white, crumbly, solid, that is odorless. Its applications are very widespread: It is an antacid and laxative; as a fertilizer; in the manufacture of heat resistant materials; in cosmetics to increase opacity and adjust the pH level; and is even a food additive for anti-caking purposes.
Magnesium phosphate, Mg3(PO4)2, is a salt of magnesium and phosphate. It is a slow-acting leavening acid, which is a group of acids that help form chemical leavening systems. Think of a fresh loaf of bread- It is crumby, light, and airy. Without a leavening agent, gases within the dough will never release, resulting in a depressing bread. Compare it to baking soda! Therefore, magnesium phosphate is growing in popularity in the baking industry, which means that we get to eat more delicious bread and pastries.
This mineral occurs in human bones, ores, and plant seeds, and presents itself as a white, crystalline powder. It is soluble in salt solutions, and when it reacts with water, it forms phosphoric acid and magnesium hydroxide. Magnesium phosphate’s applications go beyond baked goods. It coats wood to make it fireproof. It is also taken as a dietary supplement to build bone strength, fight fatigue, and regulate muscle function.
Isolation of Magnesium
As stated, magnesium is an extremely abundant metal. However, it is never found in its pure form and must be separated from its compounds. There are a few methods for refining magnesium, which we will go through:
To extract magnesium from dolomite and magnesite ores, they must go through an electrochemical process. First, the dolomite is crushed and mixed with seawater. As this mixture heats, insoluble magnesium hydroxide separates and sinks to the bottom. This is then filtered out and combined with hydrochloric acid to form magnesium chloride. This new compound then gets dried and electrolyzed to release magnesium.
Dr. Lloyd invented the Pidgeon process to produce pure magnesium metal. This process exemplifies thermal reduction. The first step is to crush dolomite ores and calcinate them by roasting them at high temperatures. By doing so, the compound releases carbon. Next, a reducing agent is needed, ferrosilicon; It gets crushed and mixed with the calcined dolomite. Then, retorts, or reduction chambers, get filled with this mixture. Lastly, crowns of crude magnesium metal crystals form at the top of the retort as it heats.
Magnesium Oxidation States
Magnesium in its elemental state has an oxidation number of 0. However, magnesium compounds are almost always in a +2 oxidation state.
Properties of the Element Magnesium
- Magnesium Symbol: Mg
- Melting point: 923 K; 650°C; 1202°F
- Boiling point: 1363 K; 1090°C; 1994°F
- Density: 1.74g/cm3
- Atomic weight: 24.305
- Atomic number: 12
- Electronegativity: 1.31
- Classification: Alkaline metal
- Natural abundance in the Earth’s crust: 2%
- Electron shell configuration: [Ne] 3s2
- Isotopes: Magnesium-24
- Found naturally in the minerals: 60 minerals contain magnesium, including magnesite and dolomite
- Toxicity: Nontoxic
Where can I buy Magnesium?
Amazon and specialty stores sell magnesium metal.