Brief History of Sodium
Sodium was discovered by a Sir Humphrey Davy in 1807 in England. Davy first isolated this element through the electrolysis of solid sodium hydroxide (NaOH). This method involved melting the compound, in this case NaOH, of sodium, then passing an electrical current through the melted compound. Before Davy performed this experiment in the 18th century, there was no real distinction made between sodium and potassium. This is because the scientists at the time did not recognize the difference in terms of where they were derived from. The compound potassium carbonate (K2CO3) comes from deposits in the earth, categorized as a “vegetable alkali”. The compound sodium carbonate (Na2CO3) however, is categorized as a “mineral alkali”. It is derived from wood ashes. It was only later on that this distinction between sodium and potassium was made.
Sodium is never found as is in nature. Attempting to extract sodium from compounds is not very easy, as it forms a very strong bond(s) with other elements, therefore, making the bonds very difficult to break.
Nonetheless, sodium is always found within a compound, as it is too active to exist by itself. It is the most abundant of the alkali metals. Halite is the most common source of sodium on the Earth. It is basically near pure sodium chloride (NaCl). Another sodium compound that exists in nature is sodium carbonate. This compound is probably the best known sodium compound to the previous generations of people. When heated with calcium oxide, and left to cool, a hard transparent material is created, otherwise known as glass. Glass was made on a large scale in Egypt from 1370 B.C. and onward. Because of this early creation, glass is considered to be one of the first chemical products manufactured by people.
The name of this element (sodium) is believed to have come from an Arabic word suda, meaning “headache.” Suda (Soda) was occasionally used as a remedy for headaches in the past. It is also conjectured that the word derives from the English word “soda.” This name was eventually passed down to the Latin language to become sodanum, which means “headache remedy,” similar to the Arabic word. The symbol for sodium, Na, derived from the Latin word “natrium.”
Description of Sodium as an Atom, Element, and in Compounds
Sodium is part of the alkali family, belonging under group 1 in the periodic table of elements. Other alkali metals in this group include lithium, potassium, rubidium, cesium, and francium. These elements are some of the most active elements in the periodic table. Sodium has an atomic number of 11. It has an atomic mass of 22.98977 g/mol. Thus, sodium has 11 electrons, 11 protons, and ~12 neutrons. It has 1 electron on its valence shell, and 8 and 2 electrons on its second and first energy level respectively. Its electronic shell formula is –[Ne] 3s1. Its oxidation state is +1. Its density is 0.97g/cm3. Its atomic radius is 180 pm. Its melting point is 97.5°C, and its boiling point is 883°C. Sodium is never found as a lone element in nature. It is always found within compounds. This is because sodium is much too reactive to exist on its own. Halite, which is nearly pure sodium chloride, is the most common source of sodium in the Earth. Sodium has a number of isotopes, including sodium-23, which is naturally occurring, and sodium-22 and sodium-24, which are radioactive isotopes. It is relatively hard to extract sodium from sodium compounds because it forms very strong bonds with other elements. Having said that, sodium can be extracted from compounds through electrolysis, which involves running an electric current through molten sodium chloride. This is a similar method to the one that Davy used to first discover sodium. However, sodium by itself does not have very many uses. It is sodium compounds that are used widely in today’s fields.
Sodium is commonly found within compounds. A majority of sodium compounds dissolve in water. In nature, rain dissolves sodium compounds, and they eventually end up in bodies of water. In fact, these dissolved compounds are part of the reason why the ocean is salty today. Because these dissolved sodium compounds are carried into the ocean, finding them on land is quite deviant. Probably the only place that sodium compounds can be found on land is in deserts, due to low rainfall. In terms of the compounds sodium can be found in, some of the important ones include sodium chloride, sodium carbonate, and sodium bicarbonate. Applications of these sodium compounds are explained in a subsequent section of this report.
Physical Properties of Sodium
At room temperature, sodium is a solid. It is a silvery white metal with a soft, waxy appearance. In fact, it is so soft, that it can be cut with a regular knife. When first cut, its surface is shiny and bright, but quickly reacts with the oxygen in the air, forming a thin layer of sodium oxide (Na2O) around the sodium, covering it. Sodium has a melting point of 97.5°C, and a boiling point of 883°C. A high melting and boiling point means that sodium forms very strong bonds with other elements, making them difficult to break. Its density is 0.97g/cm3, which is slightly less than water. Furthermore, sodium is a good conductor of electricity and heat.
Chemical Properties of Sodium
Sodium is one of the most reactive elements in the periodic table. When exposed to oxygen at room temperature, it reacts almost instantly, forming sodium oxide. When sodium is heated, in combines with oxygen expeditiously, burning and emitting a golden yellow flame. Sodium reacts very violently with water, so it cannot be stored in water. Instead, sodium is stored in liquids which it does not react with, such as kerosene or naphtha. When sodium comes into contact with water, the sodium floats because it has a lower density. However, after a few moments, an extreme exothermic reaction occurs, so strong that the heat can ignite the hydrogen gas that is released. If large pieces of sodium are used in the reaction, loud explosions can also occur in addition. Sodium can react with unsaturated hydrocarbon compounds with double bonds to make them saturated through a reaction known as an addition reaction. One product that can be made through this type of reaction is what is known as buna, or synthetic rubber. In terms of sodium’s reaction with alcohols, a compound called alkoxide is formed. In this reaction, sodium replaces one hydrogen atom, similar to the reaction between sodium and water.
Technological Applications of Sodium
There is a multitude of applications of sodium. As already mentioned, table salt is one of the largest applications of sodium. Other sodium products include baking soda, baking powder, soaps and detergents and aspirin/medical drugs.
Sodium chloride is more commonly known as table salt. Sodium chloride is added to foods as a flavour enhancement, but also to prevent food from spoiling (known as food preservative). Furthermore, sodium chloride is used as an initial element to create other sodium compounds. Sodium carbonate is used in the glass making process, which is probably the most important use of this compound. As well, sodium carbonate is growing in terms of its use in water purification and sewage treatment.
Sodium carbonate reacts with other chemicals in the “polluted” water, forming a solid. This solid sinks to the bottom of the tank, carrying all impurities down with it. Sodium carbonate is also used to make pulp and paper, soaps and detergents, and textiles.
Sodium bicarbonate produces a fizzing reaction when dissolved in water. This reaction is especially helpful in baking, as it is used in baking soda to help batter rise. Alka-Seltzer, a type of medication, also includes sodium bicarbonate in its tablets. This fizzing reaction is what helps to relieve the stomach. Other applications of sodium bicarbonate include mouthwashes, cleaning solutions, and fire extinguishers.
In terms of the technological aspect, there are quite a few applications. Two radioactive isotopes of sodium, sodium-22 and sodium-24, are used in medicine and medical applications. These isotopes can be used as tracers to follow and track sodium in a person’s body. A tracer is a radioactive isotope in which its presence can be easily detected. The isotope is injected into the person’s system, and it gives off radiation. This radiation can be tracked and followed by detectors.
Similarly, sodium-24 and the fact that it emits radiation can help to identify leaks in oil pipes. These pipes are usually buried underground, making it difficult to locate a break in the pipe. By adding sodium-24 to the oil, it will leak out of the pipe through the break. As the isotope travels through the pipe prior to the break, it can be tracked using detectors that can pick up the isotope’s radiation.
Sodium is also used as a heat exchange medium in nuclear power plants. A heat exchange medium is a substance that can absorb heat in one place, and carry it and emit it at another place. In the case of a nuclear power plant, nuclear sodium confined in pipes surround the core of the reactor, where heat energy is emitted. The sodium absorbs the heat, and is forced through the pipes to a place where it can emit its heat to nearby water pipes. The heat from the sodium converts the water into steam, which can be used effectively to produce electricity.
Furthermore, sodium can be used in the process to make synthetic rubber, also called buna. A starting molecule continually reacts with itself to produce a polymer. This polymer is the material that makes up the synthetic rubber. In the reaction, sodium is used as a catalyst.
Sodium is also used in light bulbs and street lights. Combining and electric current and sodium vapour produces a yellow-orange glow, otherwise known as yellow-orange light. In light bulbs, sodium gas in put into the bulb. As an electric current is passed through the filament, it causes the sodium vapour to emit a yellow-orange glow.
Aside from technological applications, sodium is very important for us humans. Sodium chloride is most commonly found in the food we consume. It assists in maintaining the blood pressure of our body, as well as regulating the bodily fluids. It also has a critical role in nerve transmission and the contraction of muscles. Our kidneys are the organs that regulate the sodium levels in our body. When sodium levels are low, the kidneys store it, and when they are high, the kidneys excrete it through urine. Sodium can accumulate in your blood if your kidneys cannot properly eliminate enough sodium. Blood volume increases because sodium attracts and holds water, making the heart work harder to pump blood through the vessels, thereby, increasing pressure. Certain diseases can contribute to your body’s inability to regulate sodium levels, such as heart failure, cirrhosis, and chronic kidney disease.
Material Data Safety Sheet for Sodium
The follow link is an MSD sheet for sodium: http://www.sciencelab.com/xMSDS-Sodium-9924951
Careers Associated With/Involving Sodium
Because the use of sodium and sodium compounds is widespread, there are a great number of jobs and careers that involve the use of sodium/sodium compounds. These jobs/careers include: food chemist, water sanitation inspector, doctors and surgeons, and civil engineers.
R.Flores.
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