Elements

The Salty Element Sodium

The Element Sodium

Introduction to Sodium

The element sodium is a soft, flammable, silvery-white metal. Sodium, named after the English word ‘soda’, has compounds which are commonly used in our day-to-day lives. You might be familiar with table salt, which is NaCl (sodium chloride), a compound of sodium. It is one of the most reactive metals on the periodic table.

Ten Interesting & Fun Facts About Sodium

  1. The monthly allowance of Roman soldiers was referred to as ‘salarium’ – in which ‘sal’ is Latin for salt. That is to say, Roman soldiers were often paid their allowance in salt, which was considered quite valuable in their time. 
  2. Sodium is the sixth-most abundant element on Earth. 
  3. Interestingly, 0.15% of your body is sodium.
  4. Sodium density is lower than that of water’s. 
  5. The element sodium accounts for 2.6% of the Earth’s crust. 
  6. A knife can cut through sodium metal quite easily.
  7. Sodium only has one stable isotope. 
  8. Latin for sodium carbonate is ‘natrium’. So sodium’s elemental symbol ‘Na’ is derived from this word. 
  9. Researchers are trying to learn about different the sodium content of different stars, in order to predict their evolution. 
  10. Large quantities of sodium were disposed of in a lake in an explosive fashion after WWII (https://www.youtube.com/watch?v=HY7mTCMvpEM).

Sodium in the Periodic Table

Sodium, atomic symbol Na, has an atomic number of eleven, and lies in group 1 on the periodic table, below lithium and to the left of magnesium. This element is in the alkali metals family, and it has only one valence electron. Hence, it’s a very active element. Furthermore, sodium will readily bond with any element that needs a single electron.

Sodium has an electronegativity of 0.93 (Pauling Scale). Sodium’s electron configuration is 1s22s22p63s1. Other elements in the alkali metals family include: potassium, lithium, cesium, and rubidium. Additionally, speaking of potassium, sodium and potassium’s chemical and physical properties are quite similar.

The Element Sodium in Our Bodies

The element sodium is extremely vital for our bodies. It acts as an electrolyte and mineral that regulates the fluid in our cells. Sodium also maintains our nerve functions, muscle movement, and electrolyte balance. Moreover, this sodium enters our bodies through consuming foodstuffs, and it exits in the form of perspiration/urination. During this ‘cycle,’ our blood/lymph fluids store the sodium. Furthermore, if this sodium reaches unhealthy levels, then our bodies react to this change – sometimes, in the form of diarrhea, malnutrition, or hyponatremia/hypernatremia. Hence, it’s very important that we monitor our body’s sodium levels by regulating our diets. 

Alloys of the Element Sodium

Sodium forms alloys with several elements, including potassium, calcium, and lead. Let’s discuss a few alloys and their uses/properties. To begin with, the alloy of sodium and potassium (NaK) is used in various processes (e.x. NaK acts as a heat transfer coolant, as a reducing agent, and catalyst). This alloy, called NaK, typically a liquid at room-temperature, is dangerously reactive with water and air. Moving forward, sodium is also present in the ternary alloy, containing potassium and cesium (NaKCs), and in sodium amalgam, an alloy of sodium and mercury. Sodium amalgam acts as a reducing agents and aqueous suspensions. 

Sodium Applications in Today’s World

What is Sodium Used For?

Sodium as a Heat Exchanger

Heat exchangers are devices that transfer heat from one place to another. Sodium is a commonly-found heat exchanger in nuclear power plants. Furthermore, it’s sodium’s task to carry the heat from these plants’ reactors, to transfer it to a water supply – which uses this heat to generate steam, and power electricity. 

Using Sodium to Produce Other Materials

Sodium compounds are used to produce various materials. Firstly, they’re used to produce paper. In the paper-making process, sodium hydroxide treats/separates fibers in the pulling phase. Secondly, they’re used to produce clear glass. In this process, we heat sodium carbonate with calcium oxide. Thirdly, sodium compounds are used in creating different metals. For example, sodium combined with titanium tetrachloride produces titanium metal. In another reaction, sodium is a catalyst to create artificial rubber. Similarly, there are other materials (e.x. foodstuffs and fertilizer) which involve sodium in their production/usage. 

The Element Sodium in Sodium-vapour Lamps

Sodium-vapour lamps generate a yellow, monochromatic glow, which illuminates streetlights. These lamps contain electrodes, metallic sodium, and forms of neon and argon. When current passes through the ionized neon and argon – it vaporizes the metallic sodium, and the sodium ionizes to generate a shiny, yellow glow. 

The element sodium of the periodic table
Streetlights can be illuminated through sodium vapour-lamps

When and How Was Sodium Discovered? 

The History of Sodium

Surprisingly, the element sodium was used in the prehistoric times for a number of reasons. Its compounds has uses in flavoring, relieving headaches, and manufacturing glass. These sodium compounds were derived from various sources. For example, sodium carbonate was derived from the ashes of special plants, whereas sodium chloride was derived from seawater. Needless to say, sodium’s versatility attracted several scientists and chemists to look into its composition.

Who Discovered Sodium?

One of these chemists included Sir Humphrey Davy, who in 1807, performed electrolysis on caustic soda to attain pure sodium. This reaction, powered by three large batteries, was similar to the reaction for isolating potassium. 

Where is Sodium Present in the Universe?

Sodium is present in high quantities in the sun and stars. The D lines of sodium (spectral lines) are among the most prominent in the solar spectrum. They are known as Fraunhofer lines. Sodium is the seventh most abundant element on earth, comprising about 2.27% of the earth’s crust.

The electrolysis of absolutely dry fused sodium chloride is the commercially-favored method for producing pure sodium. This method costs significantly less than the method used several years ago; as a result, it is more popular these days. The old method, the Castner process, electrolyzed sodium hydroxide. Additionally, the mineral halite, containing sodium chloride, is present all over the planet.

Sodium Chemistry – Compounds, Reactions, Oxidation States, Isolation

Chemical Properties of Sodium Element

Sodium is very active, and it will react with most non-metals. Hence, to avoid these reactions, we keep/store sodium in inert liquids (e.x. kerosene) or in nitrogenous atmospheres. Here is a list of a few reactions that occur with sodium: 

  • Sodium and air: if exposed, sodium will react with oxygen and it will form sodium oxide. However, this sodium oxide will quickly react with hydrogen and the outcome will be sodium hydroxide. In another aspect, burning sodium in the air produces sodium peroxide.
  • Sodium reacts with all halogens to produce sodium halides. These reactions will produce sodium chloride, sodium iodide, and sodium bromide amongst other compounds.
  • Sodium will react with hydrofluoric and hydrochloric acids in very exothermic reactions. 

How does Sodium React with Water?

Sodium having a single valence electron makes it very reaction. When mixing sodium metal and water, sodium’s reaction with water can be violent. To begin with, sodium floats when placed on water. This is because sodium’s density is lower than that of water’s. Subsequently, an exothermic reaction will occur, and a solution of sodium hydroxide and hydrogen gas will form. This reaction releases so much heat that the sodium melts and releases the hydrogen from the added water. Further, this released hydrogen gas can catch fire. 

Sodium Compounds

The element sodium readily forms compounds with just about any anion. Most sodium compounds are soluble in water. Here are a few common sodium compounds, their properties, and uses: 

Sodium Acetate

  • Sodium acetate, also called ‘acetic acid’, is highly soluble in water. It is a source of sodium ions, a seasoning agent in flavour foods, and found in hand warmers. 

Sodium Benzoate

  • This compound is a white, odorless compound; combining sodium hydroxide and benzoic acid produces it. Sodium benzoate will ‘dissemble’ into sodium and benzoic acid ions if placed in water. This compound is widely present in food preservatives. 

Sodium Bicarbonate

  • Sodium bicarbonate is a white, crystalline powder that’s a solid at room temperature. Commonly referred to as baking soda, it has a handful of uses as an antacid. For example, it neutralizes excess stomach acid, and relieves heartburns amongst other painful sensations. Moreover, sodium bicarbonate’s alkaline nature allows it to react with acids, making it a commonly used baking ingredient and in dry chemical fire extinguishers.

Sodium Bromide

  • Sodium bromide is a white solid that’s readily soluble in water and has various uses. It acts as a catalyst, reagent, disinfectant, and as a source of bromide ions. Moreover, the reaction between sodium hydroxide and hydrogen bromide produces this compound. It is not present in nature.

Sodium Carbonate

  • Sodium carbonate, also called ‘soda-ash,’ is a white crystalline solid, soluble in water. This alkaline salt is derived from salt and limestone, and is used as a food additive and cleaning agent – amongst other things.  It is also sold as washing soda, which is different than baking soda.

Sodium Chloride

  • Sodium chloride is a white, crystalline solid that’s readily soluble in water. NaCl is famous for its function in the kitchen as table salt, where it adds flavor to food. Nevertheless, sodium chloride is prepared through refining seawater, and it can be used to create other chemical compounds too (e.g. sodium bicarbonate). Learn some interesting facts about salt.

Sodium Citrate

  • This compound is a white, crystalline powder. It is an alkalinizing agent. 

Sodium Fluoride

  • This compound is produced through neutralizing hydrofluoric acid with bases (for example, sodium hydroxide). It’s a white/green crystalline solid that’s soluble in water. Moreover, this compound commonly acts as a wood preservative, a chemical reagent, insecticide, and as a source of fluoride ions.  

Sodium Hydroxide

  • This compound, also called ‘caustic-soda,’ is a common inorganic base. The white, crystalline solid is produced through the electrolytic chloralkali process, and has a variety of uses. For example, it can be a preservative to protect foods, and a significant component in different medicinal products (e.x. aspirin) and in soaps/detergents as well.

Sodium Hypochlorite

  • Sodium hypochlorite is a clear solution with a yellowish hue. It is produced through the reaction of chlorine with a sodium hydroxide solution. This common bleaching agent dulls any odors when added to waste water.

Sodium Iodide

  • Sodium iodide is a white, odorless powder. To produce it, sodium carbonate reacts with an hydroiodic acid solution. Furthermore, sodium iodide often acts a reagent in organic syntheses. And it’s used to prevent iodine deficiency as it is a source of iodine.

Sodium Nitrate

  • Sodium nitrate (and sodium nitrite) are present in many food preservatives. More specifically, they preserve certain meats and cheeses.

Sodium Phosphates

  • Sodium phosphates are a group of chemicals, and these chemicals consist of sodium, phosphorus, and oxygen atoms. Monosodium phosphate is created through neutralizing phosphoric acid, and it’s used as an emulsifier. Disodium phosphate is used to soften water, and it’s produced similarly to the monosodium phosphate. Trisodium phosphate is produced when sodium hydroxide neutralizes phosphoric acid, and it’s used to produce chemicals which degrease material. 

Sodium Sulfate

  • Sodium sulfate is a white, crystalline solid. Its use lies predominantly in the manufacturing industry. Sodium chloride and sulfuric acid combine to produce it. Additionally, it’s used to produce other chemicals, paper, and glass. 

Sodium Sulfide

  • Sodium sulfide is a colorless solid. Industrially, a carbothermic reduction reaction produces it. Furthermore, this solid oxidizes when heated. Additionally, this compound is used in dissolving the lignin of wood fibres in the paper-making process, in producing rubber chemicals, and in making bleaching agents. 

Isolation of Sodium

Sodium is commonly made through the vector process. Producing elemental sodium in a small scale laboratory is extremely difficult, though. However, it can be done with difficulty by performing the electrolysis of molten NaCl, but this is dangerous and it’s difficult to recover the sodium. 

Sodium Oxidation States

Sodium exists almost exclusively in the +1 oxidation state. The colourless sodium ion is Na+. 

Physical properties of Sodium

Sodium is so soft, you can cut it with a knife. If you ever hold sodium, you should hope that it is covered in oil.

  • Symbol: Na
  • Melting point: 97.794°C
  • Boiling point: 882.940°C
  • Density (g cm−3): 0.97
  • Atomic mass: 22.990
  • Atomic number: 11
  • Electronegativity (Pauling Scale): 0.93
  • Classification: Alkali metal, Group I metal
  • Crustal abundance (ppm): 23600
  • Electron configuration: [Ne] 3s1
  • Key Isotopes: 23Na
  • Found naturally in the minerals: Amphibole, Zeolite, Halite and Cryolite
  • Toxicity: The sodium ion, Na+ is generally non-toxic. Toxicity is defined by the cation present with sodium.

Where Can I Buy Elemental Sodium?

You can buy sodium on Amazon, Ebay or through online element stores like Luciteria. You can usually purchase it for around $0.50 – $1 USD per gram. It is usually sold stored under oil. If you’re looking for table salt, then you can buy it at your local grocery store.

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