salt: Characteristics and Classification of Salts salt Characteristics and Classification of Salts The most familiar salt is sodium chloride , the principal component of common table salt. Sodium chloride, NaCl, and water, H2O, are formed by neutralization of sodium hydroxide, NaOH, a base, with hydrogen chloride, HCl, an acid: HCl+NaOH→NaCl+H2O. Most salts are ionic compounds (see chemical bond ); they are made up of ions rather than molecules. The chemical formula for an ionic salt is an empirical formula; it does not represent a molecule but shows the proportion of atoms of the elements that make up the salt. The formula for sodium chloride, NaCl, indicates that equal numbers of sodium and chlorine atoms combine to form the salt. In the reaction of sodium with chlorine, each sodium atom loses an electron, becoming positively charged, and each chlorine atom gains an electron, becoming negatively charged (see oxidation and reduction ); there are equal numbers of positively charged sodium ions and negatively charged chloride ions in sodium chloride. The ions in a solid salt are usually arranged in a definite crystalline structure, each positive ion being associated with a fixed number of negative ions, and vice versa.

A salt that has neither hydrogen (H) nor hydroxyl (OH) in its formula, e.g., sodium chloride (NaCl), is called a normal salt. A salt that has hydrogen in its formula, e.g., sodium bicarbonate (NaHCO3), is called an acid salt. A salt that has hydroxyl in its formula, e.g., basic lead nitrate (Pb[OH]NO3), is called a basic salt. Since a salt may react with a solvent to yield different ions than were present in the salt (see hydrolysis ), a solution of a normal salt may be acidic or basic; e.g., trisodium phosphate, Na3PO4, dissolves in and reacts with water to form a basic solution. In addition to being classified as normal, acid, or basic, salts are categorized as simple salts, double salts, or complex salts. Simple salts, e.g., sodium chloride, contain only one kind of positive ion (other than the hydrogen ion in acid salts). Double salts contain two different positive ions, e.g., the mineral dolomite, or calcium magnesium carbonate, CaMg(CO3)2. Alums are a special kind of double salt.

Complex salts, e.g., potassium ferricyanide, K3Fe(CN)6, contain a complex ion that does not dissociate in solution. A hydrate is a salt that includes water in its solid crystalline form; Glauber's salt and Epsom salts are hydrates. Salts are often grouped according to the negative ion they contain, e.g., bicarbonate or carbonate , chlorate , chloride , cyanide , fulminate , nitrate , phosphate , silicate , sulfate , or sulfide . Sections in this article: Sodium - Element information, properties and uses | Periodic Table Chemistry in its element: sodium (Promo) You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry. (End promo) This week an essential element with a split personality. Here's David Read. David Read Sodium, like most elements in the periodic table could be said to have a dual personality. On one side it is an essential nutrient for most living things, and yet, due to its reactive nature is also capable of wreaking havoc if you happen to combine it with something you shouldn't. As such sodium is found naturally only in compounds and never as the free element.

Even so it is highly abundant, accounting for around 2.6 per cent of the earths crust by weight. Its most common compounds include dissolved sodium chloride (or table salt), its solid form, halite and as a charge balancing cation in zeolites. Aside from being an essential nutrient, the story of man and sodium is said to begin all the way back in the time of the Pharaohs in Ancient Egypt, with the first recorded mention of a sodium compound in the form of hieroglyphics. It is difficult to describe a pictogram through speech but imagine a squiggly line over the top of a hollow eye-shape, over the top of a semicircle, with a left-facing vulture image next to them all. This pictogram meant divine or pure and its name is the root of the word natron, which was used to refer to washing soda, or sodium carbonate decahydrate, as we would know it today. Sodium carbonate was used in soap, and also, in the process of mummification thanks to its water absorbing and bacteria killing pH control properties.

In medieval Europe, however, sodium carbonate was also used as a cure for headaches, and so took the name sodanum, from the Arabic suda, meaning headache. It was this terminology that inspired Sir Humphrey Davy to call the element sodium when he first isolated it by passing an electric current through caustic soda, or sodium hydroxide, in 1807. This process is known as electrolysis and using it Davy went on to isolate elemental potassium, calcium, magnesium and barium by a very similar method. Chemistry teachers often confuse children when they tell them about chemical symbols. Whilst ones like H, N, C and O all seem perfectly logical, abbreviating sodium to Na seems counterintuitive at first. However, if we consider the word natron, we can see where the abbreviated form came from. When isolated in metallic form, silvery white sodium is a violent element, immediately oxidising upon contact with air, and violently producing hydrogen gas which may burst into flame when brought into contact with water. It is one of the highly reactive group one elements that are named the alkali metals. Like the other alkali metals, it has a very distinctive flame test - a bright orange colour, from the D-line emission.

This is something you will have seen in all built up areas in the form of street lamps, which use sodium to produce the unnatural yellow light bathing our streets. This effect was first noted in 1860 by Kirchoff and Bunsen of Bunsen Burner fame. Almost all young chemists will have done a flame test at some point, and sodium chloride is a popular choice. Unfortunately, the intensity of the colour is such that if any of the compound is spilled into the Bunsen burner, it is cursed to burn with a blue and orange speckled flame seemingly forever. The reaction of sodium with water is a favourite demonstration, and clips of it abound on the internet. Sodium and its compounds have applications so diverse it would be impossible to mention them all here, a couple of examples include the fact that sodium is used to cool nuclear reactors, since it won't boil as water would at the high temperatures that are reached. Sodium hydroxide can be used to remove sulfur from petrol and diesel, although the toxic soup of by-products that is formed has led to the process being outlawed in most countries.

Sodium hydroxide is also used in biodiesel manufacture, and as a key component in products that remove blockages from drains. Baking soda actually contains sodium (it's in the name!) and its chemical name is sodium bicarbonate, where I'm sure you've come across it in baking or cooking where it undergoes thermal decomposition at above 70°C to release carbon dioxide - which then makes your dough rise. It is as an ion, however, that sodium really becomes important. An average human being has to take in around two grams of sodium a day - and virtually all of this will be taken in the form of salt in the diet. Sodium ions are used to build up electrical gradients in the firing of neurons in the brain. This involves sodium (and its big brother potassium) diffusing through cell membranes. Sodium diffuses in and is pumped back out, while potassium does the reverse journey. This can take up a huge amount of the body's energy - sometimes as much as 40 per cent. I'd like to end with a brief story which highlights the dual personality of sodium.

One man bought three and a half pounds of sodium metal from the internet and spent the evening reacting it with water in various shapes and sizes whilst he and his friends watched from a safe distance. The party was apparently a success, but he doesn't suggest hosting your own. The following day when the host came outside to check the area where he detonated the sodium was clear, he noticed that it was covered in swarms of yellow butterflies. After doing some research, he found that these butterflies had an interesting habit. The males search for sodium and gradually collect it, presenting it to their mates later as a ritual. So, that sums up the two faces of sodium. Its violent reactive nature contrasted with its use by amorous butterflies. Meera Senthilingam That was Southampton university's David Read with the two faced chemistry of sodium. Now next week, the chemical equivalent of train spotting. Brian Clegg It's easy to accuse the scientists who produce new, very heavy elements of being chemistry's train spotters. Just as train spotters spend hours watching for a particular locomotive so they can underline it in their book, it may seem that these chemists laboriously produce an atom or two of a superheavy element as an exercise in ticking the box.

But element 114 has provided more than one surprise, showing why such elements are well worth investigating. Meera Senthilingam And to find out why element 114 is worth the effort join Brian Clegg in next week's Chemistry in its element. (Promo) Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists.com . There's more information and other episodes of Chemistry in its element on our website at chemistryworld.org/elements . (End promo) Sodium Chloride The Molecular Biology of Nutrition The Sodium/Chlorine Reaction What happens when you combine chlorine (a poisonous gas) with sodium (a toxic metal)? You get table salt (sodium chloride), a crystal that dissolves into two essential nutrients. How are two toxic substances transformed into nutrients? They combine as atoms, and separate as ions. When sodium and chlorine atoms come together to form sodium chloride (NaCl), they transfer an electron. The sodium (Na) atom transfers one electron to the chlorine (Cl) atom, so that they both have full outer shells. With filled outer shells they are no longer chemically active and can't form covalent bonds to become part of a molecule.

With the transfer of the electron, however, they become electrically charged, and combine into salts through the formation of ionic bonds. The sodium ion now has only ten electrons, but still has eleven protons. This upsets the balance of charges between the protons and electrons, which causes the sodium atom to have a net positive charge. When this happens, the atom is called a positive ion. The chloride ion now has eighteen electrons and seventeen protons, so it's become a negative ion. Because the sodium ion has a positive charge, and the chlorine ion has a negative charge, they are attracted to each other, and form an ionic bond. Ions form salts, not molecules, but they perform many important functions in nutrition. Sodium and Chlorine Sodium and chlorine are both very reactive in their pre-ionic states. They will transfer electrons and (in dry conditions) form salts when they encounter each other. Each one will react with other elements if they don't find each other first, so they are seldom found in nature in their reactive states. They usually arrive on our plates together as table salt (or it's dissolved ions). In our bodies, however, they aren't bound together as salt, but dissolve back into individual ions in water.

And while they complement each other in many biological processes, they also have their separate roles to play. We've already seen what happens when sodium and chloride combine. Now we'll look at each of them individually. First we'll examine them as reactive atoms, and see why they are toxic in this state. Then we'll look at them in their ionic form and find out why they have nutritional value. The Sodium Atom When most people think of sodium, they think of table salt. While table salt contains an ionized form of sodium (in combination with chloride), non-ionized "metallic" sodium has a very different set of chemical properties than the sodium ions in table salt. We examine the chemical properties of sodium in its reactive (toxic) state here, and look at sodium in its ionic (nutritional) state in the next section. The sodium atom (Na) has eleven protons and eleven electrons, giving it a neutral (balanced) electrical charge. It has only one electron in its outer shell, however, which makes it chemically reactive. To be chemically stable it needs to have a full outer shell.

It's easier to get rid of one outer electron than it is to aquire seven more electrons, so it looks to give up the electron. The outer electrons of each sodium atom aren't desired by any of the sodium atoms, so a cloud of unwanted electrons form. The random motion of the electrons in this cloud cause shifts in the electrical properties of the individual atoms, which in turn cause the atoms to be mildly attracted to each other. These small electrical imbalances initiate metallic bonding at room temperature, causing the atoms to clump together into a soft metal you can cut with a knife. The combination of metallic sodium atoms with each other is relatively uneventful. To understand why metallic sodium is so reactive, let's see what happens when it comes into contact with water. Water (H2O) is a molecule consisting of two hydrogen atoms covalently bonded to an oxygen atom. These bonds are formed because the oxygen atom needs two electrons to fill its outer shell, and each hydrogen atom needs one electron. The formation of the water molecule conveniently fills the outer shells of all three atoms, which is why water molecules form from the two gases.

Metallic sodium in Water The molecular bonds formed by the hydrogen and oxygen atoms in water are so weak they often break apart due to random thermal energy. So when sodium wants to get rid of its extra electron, water is an easy target. One of the hydrogen/oxygen bonds in water is easily broken, and the sodium atom donates its unwanted electron, filling the vacated space in oxygen's outer shell. Because the donated electron moved from a high energy state around sodium to a lower energy state around oxygen, extra energy is released. This ScienceFix video shows how explosive the chemical reaction can be. The Sodium Ion Table salt contains sodium in its ionic form. That's why it doesn't explode on contact with water, and why it has nutritional value. It complements the chloride ion because they have opposite charges which balance each other in many biological processes. Sodium also complements potassium, because while they are both positive ions, they are also chemically different. The chemical differences between sodium and potassium are useful in controlling diffusion across our cell membranes, while the electrostatic differences between sodium and chloride are important in maintaining an electrical imbalance across those same cell membranes. To see how sodium uses these differences to enable signal transmission in nerve and muscle cells, see the article on diffusion .

Sodium is an essential nutrient in animal cells, but it's possible to get too much of a good thing. While low sodium levels can cause muscle cramps due to nerve and muscle cells not being able to control signal transmission and reception, too much sodium can cause problems like high blood pressure. When we consume sodium, it's absorbed into the bloodstream and extracellular spaces. While it's normal for the extracellular spaces to have a much higher concentration of sodium than is found inside the cell, (the imbalance is used for signal transmission), it can be taken too far. If too much sodium builds up in the bloodstream and extracellular fluids, it will dilute water concentrations outside of the cells. Water will diffuse from high concentrations inside the cell to the lower concentrations outside of the cell, including the bloodstream. This causes cell dehydration and higher blood pressure. When water flows out of nerve cells that are located in the hypothalamus, osmoreceptors in those cells trigger the thirst sensation. By drinking water, we dilute the sodium in the bloodstream, which reverses the flow of water back into the cells. The kidneys monitor sodium levels in the bloodstream and eventually remove the excess sodium and water, placing them in the urine.

Despite this corrective process, routine overconsumption of sodium can result in chronic high blood pressure, since the kidneys can only compensate so much. The Chlorine Atom The center of the chlorine (Cl) atom contains seventeen protons which are surrounded by seventeen electrons, giving it a neutral (balanced) electrical charge. It has seven electrons in its outer shell, and needs one more, which makes it chemically active. It will fill its outer shell by pairing up with other chlorine atoms to form small molecules, but these covalent bonds are weak and chlorine will abandon them when it comes into contact with an element from which it can steal an electron. Due to its chemical properties it's a gas at room temperature, making it especially dangerous. It's so toxic when inhaled, it was used as a chemical weapon in the first World War. We use it today in small amounts as a disinfectant. When a chlorine atom comes into contact with a hydrogen atom it forms a molecule of hydrogen chloride (HCl). This enables chlorine to fill its outer electron shell with hydrogen's electron, but hydrogen's nucleus (a proton) also comes along for the ride.

When hydrogen chloride comes into contact with water (H2O) it transfers the proton to the water molecule, which creates two charged molecules (HCl becomes Cl-, and H2O becomes H3O+). These two molecules dissolve into additional water molecules to form a highly acidic solution called hydrochloric acid. If chlorine gas is inhaled into the lungs, it will combine with hydrogen (from water molecules) to create hydrogen chloride, and then react with water to form hydrochloric acid, causing severe damage. If hydrogen chloride is excreted into the stomach, it combines with water to form hydrochloric acid, an aid to digestion. What's the difference between a toxin and a nutrient? Sometimes it's nothing more than location! The Chloride Ion Once you get chlorine into its ionic form (chloride) it offers many nutritional benefits. As a negative ion, chloride not only plays an important role in signal transmission, but also chemically reacts with hydrogen and water to create hydrochloric acid, a solution that helps with digestion.

Hydrochloric acid is created when Parietal cells that line the stomach use the chloride ion (Cl-) as an aid to digestion by combining it with a hydrogen ion (a proton, H+) to become hydrogen chloride (HCl). When the parietal cells secrete the hydrogen chloride into the stomach, it chemically reacts with water. In this reaction the hydrogen chloride breaks back down into the chloride ion by transfering its proton to the water molecule. The water molecule (H2O) becomes a hydronium ion (H3O+) when it gains the proton. In the presence of additional water in the stomach, these two oppositely charged ions (chloride and hydronium) stay dissolved. This combination of water, chloride and hydronium forms the solution called hydrochloric acid. Hydrochloric acid is the main ingredient of gastric (stomach) acid, which digests our food. Gastric acid's low PH level (about 1 or 2) denatures (unfolds) the proteins in our food so that enzymes in the stomach can break apart (digest) the bonds that hold the amino acids together.

Chloride (a negative ion) also interacts with sodium and potassium (both positive ions) to create and maintain the electrostatic imbalances which make signal transmissions and the transport of nutrients across the cell membrane possible. I examine these interactions (including chlorine's role), in the article on diffusion . Most of the chloride in our diet comes from table salt (sodium chloride), but it's present in a wide variety of foods. In whole foods it's especially high in tomatoes, lettuce and olives. Table Salt Table salt (sodium chloride) is a very important part of our diet. In addition to its nutritional qualities, it is used as a preservative and a flavor enhancer. Many of our foods would taste very different without it, even foods that we don't think of as being salty, like bread and milk. It's such an important part of our diet the tongue has evolved a specialized receptor to detect it. The words salt and table salt refer to two different things. Salt refers to an entire class of chemical compounds that are held together by ionic bonds (in contrast to a molecule, which is held together by covalent bonds), while table salt refers to a specific compound (sodium chloride).

Both sodium and chloride (in ionic form) combine with other substances into other kinds of salts like potassium chloride or sodium bicarbonate (baking soda). Salts can also be created from elements that don't include either sodium or chloride. The weak ionic bonds between sodium and chloride are dissolved by the stronger polarity of the water molecule, so sodium chloride doesn't exist as a salt inside the body. While sodium and chloride interact with each other in our bodies, they act as separate elements. Their nutritional value is derived not only from their ability to react with each other, but also with other atoms or molecules. These characteristics make processes like the regulation of fluid pressures and the transmission of electrical impulses possible. Why Plants Are Low in Sodium The presence of chloride, potassium and sodium in the right proportions creates an environment that enables the cell to perform it's biological functions. This is one of the reasons they are an essential part of animal diets. Sodium, however, isn't an essential nutrient for plants. While plants can (and do) use sodium when it's available, they prefer potassium. Both sodium and potassium are positive ions, so potassium can fill in for sodium when it comes to functions like electrostatic charge. Yet they still have significant differences in their chemical properties.

We need sodium to setup concentration gradients for the transmission of signals in nerve and muscle cells. Plants don't have these types of cells, so they don't need sodium for signal transmission. Animals use sodium/potassium pumps to decrease fluid pressure levels inside their fragile cell walls to keep them from bursting. Plants, on the other hand, have thicker cell walls that not only stand up to the extra pressure, but count on it to help maintain structural integrity (that's why leaves wilt when they don't get enough water). Plants use proton pumps instead of sodium/potassium pumps to maintain proton gradients, so they don't depend on sodium for any critical processes. Even more important is sodium's toxic effect on plants. Sodium is toxic for both animals and plants in high concentrations. While animals can compensate for high levels of sodium intake by removing it from their body through the kidney, plants don't have that option. In addition, animals can stop consuming sodium, while plant roots automatically absorb it from the ground during water uptake. If sodium is in the soil in large amounts, the plant will have no way of not absorbing it, and no easy way of getting rid of it once it's absorbed.

High enough levels of sodium will pull water out of cells, which is deadly for all living things. That's how it works as a preservative. Beef jerky doesn't spoil if kept dry because bacteria can't maintain enough moisture inside their cells to procreate in the presence of that much salt. That's also why people can't survive on sea water. Our kidney can remove excess salt, but only by flushing it out with water. The sodium content of sea water is so high, it requires more water to flush it out than is contained in the sea water. It makes up the difference by using water from your body, which dehydrates you. Plant roots use osmosis to bring water up into the plant. That's another reason why too much sodium in the soil is bad for plants. Sodium reverses the direction of osmosis, pulling water back out of the plant and into the soil. For all of the above reasons, all fresh fruit and vegetables are low in sodium, and many are high in potassium. Canned vegetables have lots of sodium because it's added later when processed to make it taste better. The plant didn't put it there.

sodium (Na) | chemical element | Britannica.com chemical element hydrogen (H) Sodium (Na), chemical element of Group 1 (Ia) of the periodic table (the alkali metal group). Sodium is a very soft, silvery-white metal . Sodium is the most common alkali metal and the sixth most abundant element on Earth, comprising 2.8 percent of the Earth’s crust. It occurs abundantly in nature in compounds , especially common salt —sodium chloride (NaCl)—which forms the mineral halite and comprises about 80 percent of the dissolved constituents of seawater. Properties and production Sodium is the most abundant of the alkali metals. Sodium chloride (table salt) is the most common compound of sodium, but many others also are known. Sir Humphry Davy first prepared sodium in its elemental form (1807) by the electrolysis of fused sodium hydroxide (NaOH). Sodium is an important constituent of a number of silicate materials, such as feldspars and micas. There are huge deposits of rock salt in various parts of the world, and sodium nitrate deposits exist in Chile and Peru.

Because sodium is extremely reactive, it never occurs in the free state in the Earth’s crust. The sodium content of the sea is approximately 1.05 percent, corresponding to a concentration of approximately 3 percent of sodium halides. Sodium has been identified in both the atomic and ionic forms in the spectra of stars, the Sun, and the interstellar medium . Analysis of meteorites indicates that the silicate material present has an average content of approximately 4.6 atoms of sodium for every 100 atoms of silicon . alkali metal: Lighter than water, it can be cut with a knife at room temperature but is brittle at low temperatures. It conducts heat and electricity easily and exhibits the photoelectric effect (emission of electrons when exposed to light) to a marked degree. Sodium is by far the most commercially important alkali metal. Most processes for the production of sodium involve the electrolysis of molten sodium chloride. Inexpensive and available in tank-car quantities, the element is used to produce gasoline additives, polymers such as nylon and synthetic rubber, pharmaceuticals, a number of metals such as tantalum , titanium , and silicon; it is also widely used as a heat exchanger and in sodium vapour lamps.

The yellow colour of the sodium vapour lamp and the sodium flame (the basis of an analytical test for sodium) is identified with two prominent lines in the yellow portion of the light spectrum. Significant uses neptunium (Np) Two of the earliest uses of metallic sodium were in the manufacture of sodium cyanide and sodium peroxide. Significant quantities were used in the manufacture of tetraethyl lead as a gasoline additive, a market that disappeared with the advent of unleaded gasoline. Substantial amounts of sodium are used in the manufacture of sodium alkyl sulfates as the principal ingredient in synthetic detergents. Sodium also is used as a starting material in the manufacture of sodium hydride (NaH) and sodium borohydride (NaBH4). In addition, sodium is employed in the production of dyes and dye intermediates, in the synthesis of perfumes, and in a wide variety of organic reductions. It is used in the purification of hydrocarbons and in the polymerization of unsaturated hydrocarbons. In many organic applications, sodium is used in the form of dispersions in hydrocarbon liquid media.

Molten sodium is an excellent heat-transfer fluid, and because of this property it has found use as coolant in liquid-metal fast-breeder reactors. Sodium is used extensively in metallurgy as a deoxidant and as a reducing agent for the preparation of calcium , zirconium , titanium, and other transition metals. Commercial production of titanium involves reduction of titanium tetrachloride (TiCl4) with sodium. The products are metallic Ti and NaCl. Principal compounds Sodium is highly reactive, forming a wide variety of compounds with nearly all inorganic and organic anions. It normally has an oxidation state of +1, and its single valence electron is lost with great ease, yielding the colourless sodium ion (Na+). Compounds that contain the sodium anion, Na-, have also been synthesized. The principal commercial sodium compounds are the chloride, carbonate , and sulfate . Britannica Stories Ringling Bros. Folds Its Tent The most important and familiar sodium compound is sodium chloride, or common salt, NaCl. Most other sodium compounds are prepared either directly or indirectly from sodium chloride, which occurs in seawater, in natural brines, and as rock salt.

Large quantities of sodium chloride are employed in the production of other heavy (industrial) chemicals as well as being used directly. During the period 2001–06, for example, American salt sales averaged about 28 million tons per year, of which about 16 million tons were used for ice and snow removal, 3.4 million tons for water conditioning, 1.6 million tons for food, and 2.2 million tons for the production of agricultural and industrial chemicals. Periodic Table of the Elements Other major commercial applications of sodium chloride include its use in the manufacture of chlorine and sodium hydroxide by electrolytic decomposition and in the production of sodium carbonate (Na2CO3) by the Solvay process. The electrolysis of aqueous sodium chloride produces sodium hypochlorite , NaOCl, a compound of sodium, oxygen , and chlorine used in large quantities in household chlorine bleach. Sodium hypochlorite is also utilized as an industrial bleach for paper pulp and textiles, for chlorination of water, and in certain medicinal preparations as an antiseptic and a fungicide. It is an unstable compound known only in aqueous solution. The carbonates contain the carbonate ion (CO32–).

Sodium bicarbonate , also called sodium hydrogen carbonate, or bicarbonate of soda, NaHCO3, is a source of carbon dioxide and so is used as an ingredient in baking powders, in effervescent salts and beverages, and as the main constituent of dry-chemical fire extinguishers. Its slight alkalinity makes it useful in treating gastric or urinary hyperacidity and acidosis. It is also employed in certain industrial processes, as in tanning and the preparation of wool. Sodium carbonate , or soda ash, Na2CO3, is widely distributed in nature, occurring as constituents of mineral waters and as the solid minerals natron, trona , and thermonatrite . Large quantities of this alkaline salt are used in making glass , detergents, and cleansers. Sodium carbonate is treated with carbon dioxide to produce sodium bicarbonate. The monohydrate form of sodium carbonate, Na2CO3·H2O, is employed extensively in photography as a constituent in developers.

Connect with Britannica Facebook Twitter YouTube Instagram Pinterest Sodium sulfate , Na2SO4, is a white crystalline solid or powder employed in the manufacture of kraft paper, paperboard, glass, and detergents and as a raw material for the production of various chemicals. It is obtained either from deposits of the sodium sulfate minerals mirabilite and thenardite or synthetically by the treatment of sodium chloride with sulfuric acid. The crystallized product is a hydrate, Na2SO4·10H2O, commonly known as Glauber’s salt. Sodium thiosulfate (sodium hyposulfite), Na2 S 2O3, is used by photographers to fix developed negatives and prints; it acts by dissolving the part of the silver salts coated onto film which remain unchanged by exposure to light. Sodium hydroxide (NaOH) is a corrosive, white crystalline solid that readily absorbs moisture until it dissolves. Commonly called caustic soda, or lye, sodium hydroxide is the most widely used industrial alkali. It is highly corrosive to animal and vegetable tissue.

The alkaline solutions it forms when dissolved in water neutralize acids in various commercial processes: in petroleum refining, it removes sulfuric and organic acids; in soapmaking, it reacts with fatty acids. Solutions of NaOH are used in the treatment of cellulose and in the manufacture of many chemicals. Sodium nitrate , or soda nitre, NaNO3, is commonly called Chile saltpetre , after its mineral deposits in northern Chile, the principal source. Sodium nitrate is used as a nitrogenous fertilizer and as a component of dynamite. Chemical properties Generally, elemental sodium is more reactive than lithium , and it reacts with water to form a strong base , NaOH. Its chemistry is well explored. Reaction with air, water, and hydrogen Sodium is ordinarily quite reactive with air, and the reactivity is a function of the relative humidity, or water-vapour content of the air. The corrosion of solid sodium by oxygen also is accelerated by the presence of small amounts of impurities in the sodium. In ordinary air, sodium metal reacts to form a sodium hydroxide film, which can rapidly absorb carbon dioxide from the air, forming sodium bicarbonate.

Sodium does not react with nitrogen , so sodium is usually kept immersed in a nitrogen atmosphere (or in inert liquids such as kerosene or naphtha). It is significantly more reactive in air as a liquid than as a solid, and the liquid can ignite at about 125 °C (257 °F). In a comparatively dry atmosphere, sodium burns quietly, giving off a dense white caustic smoke, which can cause choking and coughing. The temperature of burning sodium increases rapidly to more than 800 °C (1,500 °F), and under these conditions the fire is extremely difficult to extinguish. Special dry-powder fire extinguishers are required, since sodium reacts with carbon dioxide, a common propellant in regular fire extinguishers. Britannica Lists & Quizzes Eyjafjallajökull volcano Generally, alkali metals react with halogen gases, the degree of reactivity decreasing with increasing atomic weight of the halogen. Sodium is no exception to this statement. Under certain conditions of reaction, sodium and halogen vapours react to produce light (chemiluminescence).

Halogen acids, such as hydrochloric acid, react vigorously with sodium, yielding the sodium halides. The reactions are highly exothermic, with heats of reaction (energy given off) of −71.8 and −76.2 kcal, respectively, for the reactions with hydrofluoric and hydrochloric acids. Sodium is attacked by other strong mineral acids to form the corresponding salts. It reacts with the fumes of nitric acid at 15 °C (59 °F) to form sodium nitrate and with acetic and sulfuric acids to form sodium acetate and sodium sulfate. With molten sulfur it reacts violently to produce polysulfides; under more controlled conditions it reacts with organic solutions of sulfur. Liquid selenium and tellurium both react vigorously with solid sodium to form selenides and tellurides. Sodium shows relatively little reactivity with carbon, although lamellar (layerlike) materials can be prepared in which sodium is present between graphite layers. At 625 °C (1,157 °F) carbon monoxide reacts with sodium to form sodium carbide and sodium carbonate.

With the exception of the oxides of the Group 4 (IVb) metals (titanium, zirconium, and hafnium), the oxides of the transition metals are all reduced to the respective metals with elemental sodium. Sodium also reacts with a large number of metallic halides, displacing the metal from the salt and forming a sodium halide in the process. This reaction is used in the preparation of several of the transition metals themselves, including titanium and tantalum. Sodium and all the other alkali metals dissolve in liquid ammonia to give intense blue solutions, and at ordinary temperatures a slow reaction between sodium and ammonia occurs to form sodamide, NaNH2, and hydrogen, similar to the reaction of sodium with water to give NaOH and hydrogen. The reactions are Na + NH3 → NaNH2+ 1/2 H2 Na + H2O → NaOH + 1/2 H2 The reaction of alkali metal-ammonia solutions to form the amide and hydrogen can be catalyzed by the addition of many metals and metal oxides. Liquid ammonia is often used as a solvent for sodium, allowing a number of reactions to occur at ordinary temperatures that would otherwise need heat.

Sodium superoxide (NaO2), for example, can be formed by passing oxygen through ammonia solutions of sodium at −77 °C (−107 °F). Ammonia also serves as a solvent for reactions of sodium with arsenic , tellurium, antimony , bismuth , and a number of other low-melting metals. Sodium-ammonia solutions are used to blacken polytetrafluoroethylene (Teflon) to prepare its surface for cementing to other materials. The high reducing power of sodium-ammonia solutions makes them useful in a number of organic reactions known as Birch reductions. Organic reactions The organic reactions of sodium have been studied to a greater extent than those of any of the other alkali metals. Sodium reacts with anhydrous alcohols to form the respective alcoholates (or alkoxides) according to Na + ROH → RONa + 1/2 H2, in which R is the organic portion of the alcohol (R = CH3- for methanol, CH3CH2- for ethanol , etc.). The reaction is most vigorous with methanol and decreases with increasing molecular weight of the alcohol.

Sodium methoxide is produced on an industrial scale by reaction of sodium with excess methanol. Organic acids react with sodium to form sodium salts. The large negative free energy of formation of sodium halides permits the dehalogenation of a number of organic halides, the formation of the sodium halide being energetically favoured. The so-called Wurtz reaction—based on this principle—is used in organic synthesis to a considerable extent: 2RCl + 2Na → R−R +2NaCl. By this reaction, octane can be made from bromobutane and sodium. Organosodium compounds include a number in which the sodium atom is bonded directly to a carbon atom; an example is methylsodium, Na–CH3. Such compounds can be prepared by the action of sodium on mercury dialkyls or diaryls, as in the following equation: Hg(CH3)2 + 2Na → 2NaCH3 + Hg. Sodium reacts violently with a number of halogenated hydrocarbons. For example, a violent explosion occurs when a mixture of carbon tetrachloride and sodium is subjected to shock.

Even when the sodium is diluted to a considerable extent—as in sodium amalgam—a brisk reaction with carbon tetrachloride occurs. Reaction with metals Sodium is completely miscible with the alkali metals below it in the periodic table (potassium, rubidium , and cesium). A eutectic (that is, an alloy that melts lower than its components) melting at −10 °C (14 °F) is formed in the sodium-potassium system and is known commercially as NaK. Its composition is approximately 78 percent potassium, and it is used as a heat-transfer fluid and as an organic reactant. The eutectics formed in the sodium-rubidium and sodium-cesium binary systems melt, respectively, at −4.5 and −30 °C (24 and −22 °F). Sodium is the minor component with potassium and cesium of the ternary alloy NaKCs, melting at −78 °C (−108 °F). This fluid is the lowest-melting liquid alloy yet isolated. Sodium also forms alloys with the alkaline-earth metals.

Beryllium is soluble in sodium only to the extent of a few atomic percent at approximately 800 °C (1,500 °F). Liquid sodium and magnesium are only partially miscible. The degree of solubility in sodium of the alkaline-earth metals increases with increasing atomic weight, with the result that the solubility of calcium is 10 percent by weight at 700 °C (1,300 °F). In the sodium-strontium system, there is a considerable degree of miscibility. Sodium forms a number of compounds with barium , and several eutectics exist in the system. The precious metals, such as silver, gold , platinum , palladium , and iridium , and the white metals, such as lead , tin , bismuth, and antimony, alloy to an appreciable extent with liquid sodium. Cadmium and mercury also react with sodium, and a number of compounds exist in both binary systems. Seven sodium-mercury compounds, or amalgams, exist, with Hg2Na having the highest melting point (354 °C, or 669 °F).

Sodium amalgams are used chiefly for carrying out reactions in situations in which pure elemental sodium would be violently reactive and difficult to control. The solubility of transition metals in alkali metals is generally very low, often in the 1–10-parts per million range even at temperatures in excess of 500 °C (930 °F). Nuclear properties Natural sodium is the stable isotope of mass 23. Of the radioactive artificial isotopes, sodium-22 (2.6-year half-life, the longest half-life of a sodium isotope) is used as a radioactive tracer for natural sodium. Sodium-24 (15-hour half-life) is limited in use by its short life and is produced by irradiation in a nuclear reactor. Because of this reaction, a sodium-cooled reactor must have a second heat-transfer loop so that radioactive sodium does not come in contact with the environment . Other isotopes have half-lives of a minute or less. Biological properties Sodium salts, particularly sodium chloride, are found almost everywhere in biological material. Sodium is an essential element for life, as is potassium, and the two elements maintain a definite balance within the cell structure.

Electrolyte balance between the inside of the cell and the outside is maintained by “active transport” of potassium ions into the cell and sodium ions out of the cell. Most of the biological effects of sodium salts are the result of the cation (Na+), with the negative counter-ion apparently not playing a dominant role. The presence of salinity in soils is often detrimental to plant growth. Sodium ions replace calcium and other ions in clay complexes, transforming the clay to a sticky mass; water percolation is then drastically reduced, and the basicity of the soil rises markedly. The tolerance of fish to changes in salinity is often quite remarkable. Many marine bacteria and diatoms are able to tolerate salt concentrations as great as 25 percent. The minimum sodium requirement for mammals appears to be 0.05 percent of the diet, corresponding in a normal adult to a requirement of 1–2 grams (0.04–0.07 ounce) of salt per day, which results in an average sodium content of body tissues of 0.24 percent.

There is a wide variation of sodium content in the different tissues, with whole blood containing approximately 0.62 percent sodium chloride, whereas skin has a sodium content of less than 0.1 percent. There is a relationship between salt content and water balance of the body; a low salt intake causes loss of water. Considerable quantities of sodium are lost through the skin by perspiration, and considerable quantities can be excreted in the urine. Element Properties sodium - Student Encyclopedia (Ages 11 and up) Life could not exist without compounds of sodium. These compounds hold water in body tissues, and a severe deficiency of sodium can cause death. Blood contains sodium compounds in solution. Sodium compounds are used in industry in the manufacture of chemicals and pharmaceuticals, in metallurgy, in sodium vapor lamps, and in the production of hundreds of everyday products. One of the most common sodium compounds is table salt, or sodium chloride (NaCl). In its pure form sodium is a silver-white, soft and waxy metallic element. It is the sixth most abundant element on Earth and occurs in more than trace amounts in the stars and sun.

Article History Atoms, elements and compounds KENT GEOLOGISTS' GROUP Atoms, Elements and Compounds Kent Geology Atoms and Elements An atom consists of two main parts. Firstly a nucleus in which protons, having a positive charge, and neutrons having no charge, are tightly bound together. Secondly, surrounding the nucleus, are one or more electrons in shells, each of which has an associated energy level. The number of electrons is always equal to the number of protons, so the atom has no resultant charge. Atoms are very very small, typically about one ten millionth of a millimetre in diameter! The nucleus is even smaller; the diameter of the atom being about 10,000 times that of the nucleus. Because atoms are so small their dimensions are measured in nanometres. A nanometre is one millionth of a millimetre. The masses of the proton and neutron are approximately equal and are about 1800 times the mass of an electron. The simplest element, Hydrogen, has one proton and one electron. The next element, Helium, has two protons, two neutrons and two electrons.

Electrons are located in orbits or shells, each of which has a maximum complement of electrons. The numbers are two in the first, eight in the second, eight in the third and so on. When the outer shell has a full complement of electrons the element is chemically inactive. These elements are the Noble (or inert) Gases. From stability considerations the outer electron shell of other elements is 'incomplete'. These elements tend to react with other elements to achieve a complete outer shell by giving up, acquiring or sharing outer shell electrons. Chemical reactions between elements always involve the outer shell electrons. These are called the 'valency electrons'. The total number of electrons is called the 'atomic number' of the element. Compounds Compounds are products formed by chemical reaction between elements. A compound is not a mixture but a new substance, having different properties from its constituent elements. For example, sodium chloride, common salt, is a compound of sodium (a soft silvery metal) and chlorine (a greenish gas). It doesn't look or behave like either of its constituents. Explained very simply, sodium has atomic number 11.

It therefore has 11 electrons of which 2 are in the innermost shell, 8 in the second shell and 1 in the third. A complete outer shell would have 8 electrons. Sodium has one electron surplus to that required for stability and will react with other atoms. The sodium atom is shown in the diagram on the left with a blue nucleus. Chlorine (shown in the diagram with a green nucleus} has atomic number 17; that is, it has 17 electrons. Two electrons are in the first shell, 8 are in the second shell, leaving 7 electrons in the third shell. This is one short of the 8 electrons needed for a complete shell and therefore for stability. When sodium and chlorine combine chemically to form sodium chloride, the 'spare' electron in the outer shell of the sodium atom is given up to the outer shell of the chlorine atom. This gives both atoms a complete outer shell with 8 electrons, thus forming a stable compound. In losing an electron the sodium atom becomes positively charged and forms a sodium ion, written Na1+.The chlorine atom, acquiring an electron, becomes negatively charged and forms a chlorine ion, written Cl1-.

In solution, ions combine, negative charge attracting positive charge to form compounds. The way in which atoms and ions combine is determined by chemical bonding (see link below). The difference between the number of electrons in the outer shell of an atom and that required for a complete outer shell is a measure of an atom's ability to combine with others and is called its 'valency'. Sodium and chlorine (having one spare electron and one electron short respectively) have a valency of one. In simple terms, atoms can be thought of as spheres of different sizes. In forming compounds, these spheres pack together in the most compact configuration possible. In sodium chloride, the sodium and chlorine atoms form a cubic, crystal lattice as shown in the figure on the right. The compounds that can be formed will depend on the relative sizes of the atoms. If the atoms trying to form a compound are too far apart the bonding may be too weak; when close enough to form an adequate bond they may interfere. Thus not all atoms are compatible to form compounds even if their valencies suggest that it would be possible. Rockï¿½-ï¿½Forming Silicates Silicates are the most abundant rock-forming minerals.

The silicate ion is one in which one silicon atom (valency=+4) is attached to four oxygen atoms (valency=-2). The ion, SiO4 is tetrahedral in shape, that is it has four faces. with the four oxygen atoms occupying the four corners of the tetrahedron and the silicon atom at its centre. Each of the oxygen atoms has a spare valency bond.The way in which the four oxygen atoms of each tetrahedron are shared, as the silicate tetrahedra combine, determines the form of the resultant silicate mineral. In Nesosilicates (Greek, nesos = an island) such as Olivine, no oxygen links are shared and the SiO4 form is retained. In Sorosilicates (Greek, soros = a group) such as Melilite or Hemimorphite, two tetrahedra share one oxygen atom to form an Si2O7 ion. In the Cyclosilicates (Greek, cyclo = a ring) such as Tourmaline, the tetrahedra are joined in rings, each sharing two oxygen atoms.

In the Phyllosilicates (Greek, phyllo = a leaf) such as Talc and Mica, the tetrahedra are joined in sheets, sharing three oxygen atoms. Finally if all four oxygen atoms of each tetrahedron are shared, the tetrahedra form a three-dimensional structure as in the tectosilicates (Greek, tecto = a framework). Quartz and the Feldspars are tectosilicates. Formulas and Nomenclature of Ionic and Covalent Compounds Ionic compounds are compounds composed of ions, charged particles that form when an atom (or group of atoms, in the case of polyatomic ions) gains or loses electrons. A cation is a positively charged ion An anion is a negatively charged ion. Covalent or molecular compounds form when elements share electrons in a covalent bond to form molecules. Molecular compounds are electrically neutral. Ionic compounds are (usually) formed when a metal reacts with a nonmetal (or a polyatomic ion). Covalent compounds are formed when two nonmetals react with each other. Since hydrogen is a nonmetal, binary compounds containing hydrogen are also usually covalent compounds.

Metal + Nonmetal —> ionic compound (usually) Metal + Polyatomic ion —> ionic compound (usually) Nonmetal + Nonmetal —> covalent compound (usually) Hydrogen + Nonmetal —> covalent compound (usually) Transition (B-group) and Post-Transition (Group IVA and VA) Metals These elements usually form ionic compounds; many of them can form more than one cation. (The charges of the common transition metals must be memorized; Group IV and V metal cations tend to be either the group number, or the group number minus two.) Many of these ions have common or trivial names formed from the stem of the element name (the Latin name in some cases) plus the ending -ic or -ous. (-ic endings go with the higher possible charge, -ous endings go with the lower possible charge). The systematic names (also known as the Stock system) for these ions are derived by naming the metal first, followed in parentheses by the charge written in Roman numerals. For the metals below that typically form only one charge, it is not usually necessary to specify the charge in the compound name. For example, iron can form two possible ions, 2+ and 3+.

The Fe2+ ion is known as the ferrous ion (common) or the iron(II) ion (systematic); the Fe3+ ion is known as the ferric ion (common) or the iron(III) ion (systematic). The mercury(I) cation is a special case; it consists of two Hg+ ions joined together, and so is always found as Hg22+. (Hence, mercury(I) chloride is Hg2Cl2, not HgCl, while mercury (II) chloride is HgCl2.) Ions of Some Transition Metals and Post-Transition Metals (Groups IVA and VA) Metal * But note that nitrogen does not follow this pattern (i.e., nitrate, NO3-) Some nonmetals form a series of polyatomic ions with oxygen (all having the same charge): ClO-, hypochlorite; ClO2-, chlorite; ClO3-, chlorate; ClO4-, perchlorate. The -ate forms (formula and charge) must be memorized. In some cases, the -ate form has three oxygens, and in some cases four oxygens. The charge is the same for the entire series.

The -ite form has one less oxygen that the -ate form. The hypo- stem -ite form has two less oxygens than the -ate form. The per- stem -ate form has one more oxygen than the -ate form. The -ide form is the monatomic anion (see Main-Group Nonmetals ) The general rules for such series are summarized in the table below: Formula Writing Formulas of Ionic Compounds The cation is written first, followed by the monatomic or polyatomic anion. The subscripts in the formula must produce an electrically neutral formula unit. (That is, the total amount of positive charge must equal the total amount of negative charge.) The subscripts should be the smallest set of whole numbers possible. If there is only one of a polyatomic ion in the formula, do not place parentheses around it; e.g., NaNO3, not Na(NO3). If there is more than one of a polyatomic ion in the formula, put the ion in parentheses, and place the subscript after the parentheses; e.g., Ca(OH)2, Ba3(PO4)2, etc. Remember the Prime Directive in writing formulas: Ca(OH)2 ï¿½ CaOH2 !

Molecular Masses from Chemical Formulas The molecular mass, or molecular weight of a compound (measured in atomic mass units, amu) is obtained by adding up the atomic masses of all of the atoms present within a unit of the substance. For ionic compounds, the term formula mass or formula weight is used instead, since there aren't really any molecules present. The molecular/formula mass is numerically equal to the mass of one mole of the substance. For example, the molecular weight of water would be obtained by the following process: Molecular mass of H2O = (2 x atomic mass of H) + (1 x atomic mass of O) = (2 x 1.00797) + (1 x 15.9994) amu = 18.02 amu Sodium»the essentials [WebElements Periodic Table] CAS Registry ID : 7440-23-5 The picture above shows the colour arising from adding common salt (NaCl) to a burning mixture of potassium chlorate and sucrose. The chemistry of sodium is dominated by electron loss to form Na+. Cartoon by Nick D Kim ( [Science and Ink] , used by permission).

Sodium: historical information Sodium was discovered by Sir Humphrey Davy in 1807 at England. Origin of name : from the English word "soda" (the origin of the symbol Na comes from the Latin word "natrium"). Until the 18th century no distinction was made between potassium and sodium. This was because early chemists did not recognise that "vegetable alkali" (K2CO3, potassium carbonate, coming from deposits in the earth) and "mineral alkali" (Na2CO3, sodium carbonate, derived from wood ashes) are distinct from each other. Eventually a distinction was made. Sodium was first isolated in 1807 by Sir Humphry Davy, who made it by the electrolysis of very dry molten sodium hydroxide, NaOH. Sodium collected at the cathode. Davy isolated potassium by a similar procedure, also in 1807. Shortly after, Thenard and Gay-Lussac isolated sodium by reducing sodium hydroxide with iron metal at high temperatures.

Sodium is one of the elements which has an alchemical symbol, shown below (alchemy is an ancient pursuit concerned with, for instance, the transformation of other metals into gold). alt="alchemical symbol of sodium"> Sometime prior to the autumn of 1803, the Englishman John Dalton was able to explain the results of some of his studies by assuming that matter is composed of atoms and that all samples of any given compound consist of the same combination of these atoms. Dalton also noted that in series of compounds, the ratios of the masses of the second element that combine with a given weight of the first element can be reduced to small whole numbers (the law of multiple proportions). This was further evidence for atoms. Dalton's theory of atoms was published by Thomas Thomson in the 3rd edition of his System of Chemistry in 1807 and in a paper about strontium oxalates published in the Philosophical Transactions. Dalton published these ideas himself in the following year in the New System of Chemical Philosophy. The symbol used by Dalton for sodium is shown below.

[See History of Chemistry, Sir Edward Thorpe, volume 1, Watts & Co, London, 1914.] Sodium around us Read more » Sodium is a vital element. The human diet must contain a sensible amount of sodium. The sodium cation is the main extracellular (outside cells) cation in animals and is important for nerve function in animals. The importance of sodium as salt in the diet was recognized well before sodium itself was understood to be an element. This recognition formed the basis of trading of salt deposits lining the Dead Sea in biblical times by the Romans. Prolonged sweating results in sodium ion loss in sweat and it is most important that the sodium ion is replaced through proper diet. Sodium is never found as the free element ("native") in nature as it is so reactive. Sodium is the sixth most abundant element in the earth's crust at about 2.6 - 3.0%. The most common mineral is rock salt (sodium chloride, NaCl, or halite), but it occurs in many other minerals including sodium borate (borax), sodium carbonate (soda), sodium nitrate (Chile saltpetre). and sodium sulphate (thenardite).

In those species, however, it is the anions that are the reason for mining. Sodium is present in some abundance in the sun and other stars andclearly identifiable by the sodium D lines which are very prominent in the solar spectrum and those of other stars. Abundances for sodium in a number of different environments. More abundance data » Location Second ionisation energy : 4562 kJ mol‑1 Isolation Isolation : sodium would not normally be made in the laboratory as it is so readily available commercially. All syntheses require an electrolytic step as it is so difficult to add an electron to the poorly electronegative sodium ion Na+. Sodium is present as salt (sodium chloride, NaCl) in huge quantities in underground deposits (salt mines) and seawater and other natural waters. It is easily recovered as a solid by drying. Sodium chloride has a high melting point (> 800°C) meaning that it sould be expensive to melt it in order to carry out the electrolysis. However a mixture of NaCl (40%) and calcium chloride, CaCl2 (60%) melts at about 580°C and so much less energy and so expense is required for the electrolysis.

cathode: Na+(l) + e- → Na (l) anode: Cl-(l) → 1/2Cl2 (g) + e- The electrolysis is carried out as a melt in a "Downs cell". In practice, the electrolysis process produces calcium metal as well but this is solidified in a collection pipe and returned back to the melt. Sodium isotopes Is table salt an element, compound or mixture? | Reference.com Is table salt an element, compound or mixture? A: Quick Answer Common table salt, without any of the extra ingredients that may be added to the retail food product, is a compound comprised of the metallic element sodium and the non-metallic element chlorine. The chemical name for pure table salt is sodium chloride, and it is represented by the chemical formula NaCl, which indicates that each molecule consists of one sodium atom bonded to a chlorine atom. Because the bond holding the two atoms together is an ionic bond, sodium chloride belongs to the class of chemical compounds called ionic salts or ionic compounds.

Question: Common salt is a compound formed from two elements, one is Sodium, which is the other?
Answer: CHLORINE