Sodium is a chemical element with atomic number 11 in the periodic table. It’s the fourth most abundant element and comprises around 2.6% of Earth’s crust. Being a member of the alkali metals family of the periodic table, this monoisotopic element has one valence electron that makes it one of the most reactive elements in the periodic table.
Sodium chloride (or table salt) is the most common compound of this chemical element. Being an essential nutrient responsible for the transmission of the sensory impulses between the cells of our body, high sodium levels in the blood may damage cellular metabolism, cause high blood pressure, and cardiovascular diseases.
Chemical and Physical Properties of Sodium
|Atomic weight (mass)||22.989768 g.mol-1|
|Group||1 (Alkali Metals)|
|Color||A silvery-white alkali metal with a bright luster|
|Physical state||Solid at room temperature|
|Half-life||From 1.3(4)×10−21 seconds to 2.605 years|
|Ionic radius||1.02 (+1) Å|
|Most characteristic isotope||23Na|
|Electronic shell||[Ne] 3s1|
|The energy of the first ionization||495.7 kJ.mol-1|
|Uses||Few uses for pure metal; compounds in medicine, agriculture, photography. Sodium chloride (NaCl) is table salt. Liquid sodium cools nuclear reactors.|
|Description||Lightweight, malleable, silvery-white metal. Eighth most abundant in the universe. Seventh most abundant in earth’s crust.|
|Crystal Structure||Cubic: Body centered|
|Covalent Radius||1.54 Å|
|Atomic Radius||2.23 Å|
|Atomic Volume||23.7 cm³/mol|
|Name Origin||Medieval Latin: sodanum; symbol from Latin natrium.|
|Discovery date||In 1807 by Sir Humphry Davy|
With the periodic table symbol Na, atomic number 11, atomic mass of 22.990 (23) g.mol-1, and electron configuration [Ne] 3s1, sodium is soft, easily malleable, silvery-white metal with a bright luster that can be dented with any harder object. When exposed to air, sodium metal tarnishes and the substance loses its silvery luster. It also emits a brilliant yellow flame in the reaction with any of the major air components: nitrogen (N2), oxygen (O2), carbon dioxide (CO2), water (H2O).
The pure, elemental form of sodium reaches its boiling point at 882.940°C, 1621.292°F, and 1156.090 K, while the melting point is achieved at 97.794°C, 208.029°F, and 370.944 K. Even though the density of alkali metals increases with the increase of the atomic number, sodium has a higher density in comparison to potassium. This member of the alkali metals family of elements has an electronegativity of 0.9 according to Pauling, whereas the atomic radius according to van der Waals is 0.196 nm.
In contact with water, sodium creates an extremely volatile reaction that results in an explosion that releases a large amount of heat. This chemical reaction also produces sodium hydroxide and hydrogen gas. Sodium metals float in water due to their extremely low density.
How Was Sodium Discovered?
In 1807, the English chemist Sir Humphry Davy (1778 – 1829) became the first scientist who succeeded in preparing elemental sodium. Intrigued by his discovery of the electrical nature of the chemical bonding, Sir Davy came up with the idea that he could use this electricity for isolating the chemical elements from the compounds. For this, he conducted electrolysis of caustic soda which resulted in the pure form of sodium for the first time in science. The electrolysis was powered by three batteries made by this Cornish inventor.
During the experiment, Sir Davy observed a liquid substance at the wire electrode immersed in sodium hydroxide which turned into a solid and silvery-lustrous metal when exposed to room temperature. The great English chemist also succeeded in obtaining scientific evidence for the sodium’s reaction with water that produced hydrogen as a result.
Despite the lower density in comparison to the other metal elements, Sir Davy held his opinion that it should be also classified as a metal, pointing out the fact that the platinum is nearly four times as heavy as tellurium, as well as the great differences of the chemical properties among the metal elements.
How Did Sodium Get Its Name?
The name of element 11 comes from the Latin word ‘natrium’, which refers to one of the most common sodium compounds. Sir Humphry Davy himself gave the name sodium to the new metal he had discovered, for he isolated the pure form of it from caustic soda.
On the other hand, the German word for soda is ‘natronlauge’, so the name ‘natronium’ was also suggested by the German physicist and chemist L. W. Gilbert (1769 – 1824).
The Swedish chemist, Baron Jöns Jacob Berzelius, preferred the shorter form of the aforementioned term – natrium, which served as a source of the chemical symbol for sodium (Na).
Where Can You Find Sodium?
Copious quantities of sodium can be found in the heavy stars, the Sun, as well as in the region between the stars, made up of gaseous clouds and solid particles. Sodium has been traced in the aforementioned celestial objects in both its atomic and ionic form. It’s formed when atoms of neon gain a proton. Before this process, the atoms of neon are formed by the carbon atoms consolidated during nuclear fusion reactions.
On our planet, oceans are one of the richest sources of sodium. It also occurs in spring water and alkaline and salty lakes. Sodium is one of the most reactive elements of the periodic table. As a result, it can rarely be found in nature in its pure, elemental form. Hence, element 11 is often found in many mineral ores, such as soda niter, amphibole, rock salt, feldspars, zeolite, cryolite, and sodalite. Among these mineral compounds, halite (sodium chloride salt) is the mineral from which sodium is most often obtained by mining.
The first commercial quantities of sodium were produced by the Deville process that includes thermal reduction of sodium carbonate with carbon at 1,100 degrees Celsius. Also, the pure form of sodium can be obtained by electrolysis of molten sodium chloride or thermal decomposition of sodium azide.
Sodium in Everyday Life
Sodium is used in a wide array of industries where it’s used to prepare sodium compounds such as common salt, baking soda, borax, sodium nitrate, etc. Furthermore, this chemical finds application in the following instances:
- Sodium chloride (common salt) is the most commonly used compound of sodium. It is also used as a food preservative, and as a de-icing agent of roads in winter;
- Sodium compounds are appealed as reagents in the chemical industry;
- The element 11 is also used as a heat exchanger in nuclear reactors due to the high energy emitted by its volatile reactions;
- Sodium is used in many metal alloys, as well as to descale the surface of many metals;
- Metallic sodium is used in the purification process of some reactive metals, such as zirconium, as well as in the manufacture of sodamide and esters;
- Sodium bicarbonate is commonly used in the process of baking for improvement of the brad’s texture;
- Being an excellent heat transfer agent, sodium finds a practical application in the cooling of nuclear reactors;
- Disodium phosphate and tetrasodium pyrophosphate are thickening agents added to instant puddings;
- Sodium tripolyphosphate is often added to frozen food to minimize the loss of moisture during thawing of the product;
- Monosodium glutamate (MSG) sodium nitrite, sodium saccharin, baking soda (sodium bicarbonate), and sodium benzoate are sodium-rich flavor additives that add to the sodium levels in certain types of food, such as soups;
- Sodium vapor lamps are often chosen for the street lighting in the cities;
- Sodium chloride is used as a food preservation agent. By adding salt to canned or pickled food products, sodium chloride prevents the growth of bacteria, yeast, and mold in food.
Sodium and Health
Sodium is an essential mineral for all life forms and human health in particular. It supports the cellular mechanism and their ability to transmit the nerve impulses, as well as the muscle contractions and the acid-base balance. Sodium also controls and regulates the water levels in tissues and blood, stimulates adrenal glands, and helps prevent heat strokes.
Sodium and Hypertension
Because sodium attracts water, the higher the sodium levels we have in the blood – the more water is drawn into the bloodstream. The high-sodium diet increases blood volume which also contributes to increased blood pressure values.
High blood pressure (or hypertension) forces the heart to pump blood faster which can lead to damage of the arteries, heart, brain, eyes, as well as kidneys. When the blood pressure is chronically above the normal values and left untreated, it may lead to an increased risk of a heart attack, stroke, heart failure, loss of sight, kidney dysfunction, etc.
According to a study conducted by researchers from the Center for Science in the Public Interest (CSPI) in Washington, DC, fast food and processed foods are the number one reason behind the largest percent of cardiovascular diseases or high blood pressure among the American population.
While the US Food and Drug Administration, the WHO, the CDC, the U.S. Institute of Medicine, the U.S. Department of Health and Human Services, and the American Heart Association all recommend less than 2.300 milligrams (which equals 1 teaspoon of salt). The daily sodium intake of an average American is 3,400 milligrams of sodium a day.
The US Food and Drug Administration (FDA) points to the fact that the American diet is rich in processed and multi-ingredient foods (such as pizza and hamburgers) that contain more than the recommended daily intake of sodium. This increased salt intake poses a great risk of developing high blood pressure that increases with age.
What Is Sodium Deficiency?
Hyponatremia, or sodium deficiency, occurs when sodium levels in the blood are lower than 135 mmol/l. A low concentration of this alkaline element may disrupt the bodily balance of electrolytes.
What Are the Symptoms of Sodium Deficiency?
A low sodium concentration may result in the following medical conditions:
- Heart attack;
- Heart failure;
- Weight gain;
- Chronic kidney disease;
- Rise of the insulin levels in the blood.
While hyponatremia is a relatively rare occurrence with today’s lifestyle of high sodium consumption by eating mainly fast food, older adults may have more contributing risk factors for low sodium levels, including aging, taking certain medications, etc.
Including sodium-rich food in our diet is of vital importance for the proper functioning of cellular processes in our body. However, the sodium intake must be controlled, because high sodium levels may contribute to adverse health effects with sometimes fatal consequences.
According to the Centers for Disease Control and Prevention (CDC), sodium levels can add up quickly by consumption of processed food. While sodium can be evident in foods that have a salty taste, some foods that contain this mineral do not taste salty, such as cereals.
Much of sodium in our daily intake does not come from the salt shaker, but from the ‘hidden’ high amounts of this mineral in various types of food rich in sodium content, such as:
- Cured meats (cold cuts, ham, pepperoni, sausages, bacon, salt pork, jerky, etc.);
- Instant, canned, and restaurant-prepared soups;
- Cottage cheese;
- Salad dressings;
- Pizza (store-bought, frozen);
- Canned vegetables;
- Sandwiches with processed meat and cheese (hamburgers, hot-dogs, cheeseburgers);
- Snack foods (chips, microwave popcorn, crackers, fried peanuts, and pretzels);
- Processed cheeses;
- Frozen (microwave) meals;
- Bread, cereals, and baked pastries;
- Pickled vegetables;
- Soy sauce;
- Canned seafood, meat, and poultry;
- Macaroni and cheese.
To detect these ‘hidden’ sodium concentrations in food, we strongly recommend you always read the listed nutrients on the food package. Here’s a little guide created by the FDA to what some of the expressions mean:
|What The Nutrition Facts Label Says||What It Means|
|Salt/Sodium-Free||Less than 5 mg of sodium per serving|
|Very Low Sodium||35 mg of sodium or less per serving|
|Low Sodium||140 mg of sodium or less per serving|
|Reduced Sodium||At least 25% less sodium than the regular product|
|Light in Sodium or Lightly Salted||At least 50% less sodium than the regular product|
|No-Salt-Added or Unsalted||No salt is added during processing – but these products may not be salt/sodium-free unless otherwise stated|
When it comes to sodium, healthy eating and choosing food low in sodium are the key to healthy nutrition.
Being a major component of nerves and responsible for the maintenance of the balance of electrically charged particles in the body’s fluids and tissues, dietary sodium is typically administered for the treatment of diarrhea, muscle cramps, dehydration, fever, congestive heart failure, and kidney failure due to its property of holding up water in the body tissues.
Important: Please note that this sodium fact sheet is for educational and informative purposes only. This list is not complete and many other drugs may interact with sodium, including prescription and over-the-counter medicines, proton pump inhibitor (PPI) drugs, vitamins, and herbal products.
We strongly advise that you seek medical advice from a qualified healthcare provider or trained health professionals before treating any medical problems or adding sodium supplements to your diet.
How Dangerous Is Sodium?
Despite being classified as a non-toxic substance, sodium may cause caustic and thermal burns, itching, and irritation upon skin contact. Long-term exposure to sodium can also lead to chemical bronchitis, difficulty breeding, etc.
In nutrition, the dietary guidelines point out sodium as one of the most negatively influencing minerals, because excess sodium intake elevates the blood pressure and leads to more severe heart diseases, as well as problems of the central nervous system. Excessive sodium intake may also lead to kidney failure. Thus, sodium has been considered to be a nutrient of public health concern for overconsumption.
What is Hypernatremia?
Hypernatremia occurs upon high amounts of sodium in the person’s blood, i.e. concentrations higher than 145 milliequivalents per liter (mEq/l). An excess loss of water or insufficient fluid intake are some of the reasons for high sodium levels.
As an electrolyte, sodium’s role includes the regulation of water in the body. Supported by the kidneys and adrenal glands who control the sodium levels in the blood by sending signals to the neuron cells. These signals are being translated by the brain as thirst to stimulate increased sodium excretion via urine.
Hypernatremia may also cause calcium losses because the amount of calcium that our body loses via urination increases with the amount of salt we consume from the sodium-rich food and the added table salt to it.
Hamburgers and pizza are multi-ingredient dishes that are considered to contribute to almost half of the sodium that the American population consumes. In turn, this leads to increased sodium absorption, excess obesity, a high percent of cardiovascular diseases and related deaths, high cholesterol-related diseases, etc.
Environmental Effects of Sodium
Being an essential nutrient of almost all living organisms, as well as being present in large amounts in nature, this chemical element is not considered to have any harmful effects upon the environment.
Isotopes of Sodium
WIth atomic masses ranging from natrium-18 to natrium-39, there are 21 isotopes of sodium. 23Na is the only stable form of this chemical element.
There are also two radioactive cosmogenic isotopes of sodium, natrium-22 (with a half-life of 2.605 years) and natrium-24 (with a half-life of 15 hours).
|Z||N||Isotopic mass (Da)
[n 2][n 3]
[n 7][n 4]
|Natural abundance (mole fraction)|
|Excitation energy||Normal proportion||Range of variation|
|20Na||11||9||20.0073544(12)||447.9(23) ms||β+ (75%)||20Ne||2+|
|β+, α (25%)||16O|
|22Na||11||11||21.99443742(18)||2.6018(22) y||β+||22Ne||3+||Trace[n 8]|
|24Na||11||13||23.990963011(18)||14.957(4) h||β−||24Mg||4+||Trace[n 8]|
|27Na||11||16||26.994076(4)||301(6) ms||β− (99.87%)||27Mg||5/2+|
|β−, n (0.13%)||26Mg|
|28Na||11||17||27.998939(11)||30.5(4) ms||β− (99.42%)||28Mg||1+|
|β−, n (0.58%)||27Mg|
|29Na||11||18||29.002877(8)||44.1(9) ms||β− (74.1%)||29Mg||3/2(+#)|
|β−, n (25.9%)||28Mg|
|30Na||11||19||30.009098(5)||48.4(17) ms||β− (68.85%)||30Mg||2+|
|β−, n (30.0%)||29Mg|
|β−, 2n (1.15%)||28Mg|
|β−, α (5.5×10−5%)||26Ne|
|31Na||11||20||31.013147(15)||17.35(40) ms||β− (61.78%)||31Mg||(3/2+)|
|β−, n (37.3%)||30Mg|
|β−, 2n (0.87%)||29Mg|
|β−, 3n (0.05%)||28Mg|
|32Na||11||21||32.02001(4)||12.9(3) ms||β− (68%)||32Mg||(3−)|
|β−, n (24%)||31Mg|
|β−, 2n (8%)||30Mg|
|33Na||11||22||33.02553(48)||8.2(4) ms||β−, n (47%)||32Mg||(3/2+)|
|β−, 2n (13%)||31Mg|
|34Na||11||23||34.03401(64)||5.5(10) ms||β−, 2n (50.0%)||32Mg||1+|
|β−, n (15.0%)||33Mg|
|37Na||11||26||37.05747(74)#||1# ms [>1.5 µs]||β−, n||36Mg||3/2+#|
|39Na||11||28||β−, n (#)||38Mg|
List of Sodium Compounds
Sodium adopts the +1 oxidation states. When exposed to air, element 11 readily oxidizes and forms oxides. It easily reacts with oxides, acids, and acidic oxides. The most common sodium compounds are presented in the following list:
- Angeli’s salt
- Borax (sodium borate)
- Sodium cyclamate
- Disodium helide
- Disodium hydrogen arsenate
- Disodium hydrogen phosphite
- Disodium methyl arsonate
- Disodium octaborate tetrahydrate
- Disodium pyrophosphate
- Disodium tetracarbonylferrate
- Frémy’s salt
- Microcosmic salt
- Monosodium methyl arsonate
- Monosodium phosphate
- Monosodium xenate
- Soda lime
- Sodium 1,3-dithiole-2-thione-4,5-dithiolate
- Sodium alum
- Sodium aluminate
- Sodium aluminum phosphate
- Sodium aluminosilicate
- Sodium amide
- Sodium arsenate
- Sodium aurothiosulfate
- Sodium azide
- Sodium bicarbonate
- Sodium bifluoride
- Sodium bisulfate
- Sodium bisulfite
- Sodium borate
- Sodium borohydride
- Sodium bromate
- Sodium carbonate
- Sodium chromate
- Sodium cobaltinitrite
- Sodium cyanate
- Sodium decavanadate
- Sodium dichromate
- Sodium dithionite
- Sodium dithionite
- Sodium diuranate
- Sodium ferrioxalate
- Sodium ferrocyanide
- Sodium fluoride
- Sodium germanate
- Sodium hydride
- Sodium hydrosulfide
- Sodium hydroxide
- Sodium hypochlorite
- Sodium hyponitrite
- Sodium iodate
- Sodium manganate
- Sodium metabisulfite
- Sodium metaborate
- Sodium metasilicate
- Sodium metatitanate
- Sodium metatungstate
- Sodium metavanadate
- Sodium molybdate
- Sodium nitrate
- Sodium nitroprusside
- Sodium oxalate
- Sodium oxide
- Sodium perbromate
- Sodium permanganate
- Sodium peroxide
- Sodium perrhenate
- Sodium persulfate
- Sodium phosphide
- Sodium polonide
- Sodium pyrosilicate
- Sodium salts
- Sodium selenate
- Sodium silicate
- Sodium sulfate
- Sodium superoxide
- Sodium telluride
- Sodium tetraphenylborate
- Sodium tetrasulfide
- Sodium thiosulfate
- Sodium triethylborohydride
- Sodium trimetaphosphate
- Sodium triphosphate
- Sodium tungstate
- Sodium zincate
- Tetrasodium pyrophosphate
- Trisodium phosphate
Sodium Chloride (NaCl)
Sodium chloride, i.e. common salt is the most common compound of sodium is a combination of the minerals sodium (40%) and chlorine (60%). It improves or preserves the flavor of food. It is also added to baked pastries made with yeast because it contributes to the bread dough development and improves the bread texture.
5 Interesting Facts and Explanations
- According to research conducted by the Health Policy Center at the Institute of Health Research and Policy, the University of Illinois at Chicago, United States, pizza accounts for the largest percent of sodium intake in the diet of the American population, especially children and adolescents.
- Since sodium is highly reactive, the storage of the pure elemental form of this chemical element is quite a difficult task. Because it spontaneously ignites upon contact with H2O, sodium is stored in either oil or kerosene.
- Out of all the sodium that can be found on the Earth, more than 90% of it is in the form of salt.
- Cured, smoked, pickled, and brine foods contain high levels of sodium that have been added during the preparation or conservation process. In this regard, it’s worth mentioning that sea salt contains almost equal amounts of sodium as table salt.
- By replacing 15% of sodium chloride with potassium chloride, a low sodium table salt can be produced which is more beneficial for our health.