Nonmetal
In chemistry, a nonmetal is a chemical element that lacks the characteristics of a metal. Physically, a nonmetal tends to have a low melting point, boiling point, density. A nonmetal is brittle when solid and has poor thermal conductivity and electrical conductivity. Chemically, nonmetals tend to have high ionization energy, electron affinity, electronegativity, they share electrons when they react with other elements and chemical compounds. Seventeen elements are classified as nonmetals: most are gases. Metalloids such as boron and germanium are sometimes counted as nonmetals; the nonmetals are divided into two categories reflecting their relative propensity to form chemical compounds: reactive nonmetals and noble gases. The reactive nonmetals vary in their nonmetallic character; the less electronegative of them, such as carbon and sulfur have weak to moderately strong nonmetallic properties and tend to form covalent compounds with metals. The more electronegative of the reactive nonmetals, such as oxygen and fluorine, are characterised by stronger nonmetallic properties and a tendency to form predominantly ionic compounds with metals.
The noble gases are distinguished by their great reluctance to form compounds with other elements. The distinction between categories is not absolute. Boundary overlaps, including with the metalloids, occur as outlying elements in each category show or begin to show less-distinct, hybrid-like, or atypical properties. Although five times more elements are metals than nonmetals, two of the nonmetals—hydrogen and helium—make up over 99 percent of the observable universe. Another nonmetal, makes up half of the Earth's crust and atmosphere. Living organisms are composed entirely of nonmetals: hydrogen, oxygen and nitrogen. Nonmetals form many more compounds than metals. There is no rigorous definition of a nonmetal. Broadly, any element lacking a preponderance of metallic properties can be regarded as a nonmetal; the elements classified as nonmetals include one element in group 1. As there is no agreed definition of a nonmetal, elements in the periodic table vicinity of where the metals meet the nonmetals are inconsistently classified by different authors.
Elements sometimes classified as nonmetals are the metalloids boron, germanium, antimony and astatine. The nonmetal selenium is sometimes instead classified as a metalloid in environmental chemistry. Nonmetals show more variability in their properties; these properties are determined by the interatomic bonding strengths and molecular structures of the nonmetals involved, both of which are subject to variation as the number of valence electrons in each nonmetal varies. Metals, in contrast, have more homogenous structures and their properties are more reconciled. Physically, they exist as diatomic or monatomic gases, with the remainder having more substantial forms, unlike metals, which are nearly all solid and close-packed. If solid, they have a submetallic appearance and are brittle, as opposed to metals, which are lustrous, ductile or malleable. Chemically the nonmetals have high ionisation energies, high electron affinities and high electronegativity values noting that, in general, the higher an element's ionisation energy, electron affinity, electronegativity, the more nonmetallic that element is.
Nonmetals exist as anions or oxyanions in aqueous solution. Complicating the chemistry of the nonmetals is the first row anomaly seen in hydrogen, nitrogen and fluorine; the first row anomaly arises from the electron configurations of the elements concerned. Hydrogen is noted for the different ways, it most forms covalent bonds. It can lose its single valence electron in aqueous solution, leaving behind a bare proton with tremendous polarising power; this subsequently attaches itself to the lone electron pair of an oxygen atom in a water molecule, thereby forming the basis of acid-base chemistry. Under certain conditions a hydrogen atom in a molecule can form a second, bond with an atom or group of atoms in another molecule; such bonding, "helps give snowflakes their hexagonal symmetry, binds DNA into a double helix. From to neon, since the 2p subshell has no inner analogue and experiences no electron repulsion effects it has a small radius, unlike the 3p, 4p and 5p subshells of h
Diuretic
A diuretic is any substance that promotes diuresis, the increased production of urine. This includes forced diuresis. There are several categories of diuretics. All diuretics increase the excretion of water from bodies, although each class does so in a distinct way. Alternatively, an antidiuretic, such as vasopressin, is an agent or drug which reduces the excretion of water in urine. In medicine, diuretics are used to treat heart failure, liver cirrhosis, influenza, water poisoning, certain kidney diseases; some diuretics, such as acetazolamide, help to make the urine more alkaline and are helpful in increasing excretion of substances such as aspirin in cases of overdose or poisoning. Diuretics are sometimes abused by people with an eating disorder people with bulimia nervosa, with the goal of losing weight; the antihypertensive actions of some diuretics are independent of their diuretic effect. That is, the reduction in blood pressure is not due to decreased blood volume resulting from increased urine production, but occurs through other mechanisms and at lower doses than that required to produce diuresis.
Indapamide was designed with this in mind, has a larger therapeutic window for hypertension than most other diuretics. High ceiling diuretics may cause a substantial diuresis – up to 20% of the filtered load of NaCl and water; this is large in comparison to normal renal sodium reabsorption which leaves only about 0.4% of filtered sodium in the urine. Loop diuretics have this ability, are therefore synonymous with high ceiling diuretics. Loop diuretics, such as furosemide, inhibit the body's ability to reabsorb sodium at the ascending loop in the nephron, which leads to an excretion of water in the urine, whereas water follows sodium back into the extracellular fluid. Other examples of high ceiling loop diuretics include ethacrynic torasemide. Thiazide-type diuretics such as hydrochlorothiazide act on the distal convoluted tubule and inhibit the sodium-chloride symporter leading to a retention of water in the urine, as water follows penetrating solutes. Frequent urination is due to the increased loss of water that has not been retained from the body as a result of a concomitant relationship with sodium loss from the convoluted tubule.
The short-term anti-hypertensive action is based on the fact that thiazides decrease preload, decreasing blood pressure. On the other hand, the long-term effect is due to an unknown vasodilator effect that decreases blood pressure by decreasing resistance. Carbonic anhydrase inhibitors inhibit the enzyme carbonic anhydrase, found in the proximal convoluted tubule; this results in several effects including bicarbonate accumulation in the urine and decreased sodium absorption. Drugs in this class include methazolamide; these are diuretics. The term "potassium-sparing" refers to an effect rather than a location. Aldosterone adds sodium channels in the principal cells of the collecting duct and late distal tubule of the nephron. Spironolactone prevents aldosterone from entering the principal cells, preventing sodium reabsorption. Similar agents are potassium canreonate. Epithelial sodium channel blockers: amiloride and triamterene; the term "calcium-sparing diuretic" is sometimes used to identify agents that result in a low rate of excretion of calcium.
The reduced concentration of calcium in the urine can lead to an increased rate of calcium in serum. The sparing effect on calcium can be beneficial in unwanted in hypercalcemia; the thiazides and potassium-sparing diuretics are considered to be calcium-sparing diuretics. The thiazides cause a net decrease in calcium lost in urine; the potassium-sparing diuretics cause a net increase in calcium lost in urine, but the increase is much smaller than the increase associated with other diuretic classes. By contrast, loop diuretics promote a significant increase in calcium excretion; this can increase risk of reduced bone density. Osmotic diuretics are substances that increase osmolarity but have limited tubular epithelial cell permeability, they work by expanding extracellular fluid and plasma volume, therefore increasing blood flow to the kidney the peritubular capillaries. This thus impairs the concentration of urine in the loop of Henle. Furthermore, the limited tubular epithelial cell permeability increases osmolality and thus water retention in the filtrate.
It was believed that the primary mechanism of osmotic diuretics such as mannitol is that they are filtered in the glomerulus, but cannot be reabsorbed. Thus their presence leads to an increase in the osmolarity of the filtrate and to maintain osmotic balance, water is retained in the urine. Glucose, like mannitol, is a sugar that can behave as an osmotic diuretic. Unlike mannitol, glucose is found in the blood. However, in certain conditions, such as diabetes mellitus, the concentration of glucose in the blood exceeds the maximum reabsorption capacity of the kidney; when this happens, glucose remains in the filtrate, leading to the osmotic retention of water in the urine. Glucosuria causes a loss of hypotonic water and Na+, leading to a hypertonic state wit
Radical (chemistry)
In chemistry, a radical is an atom, molecule, or ion that has an unpaired valence electron. With some exceptions, these unpaired electrons make radicals chemically reactive. Many radicals spontaneously dimerize. Most organic radicals have short lifetimes. A notable example of a radical is the hydroxyl radical, a molecule that has one unpaired electron on the oxygen atom. Two other examples are triplet triplet carbene which have two unpaired electrons. Radicals may be generated in a number of ways. Ionizing radiation, electrical discharges, electrolysis are known to produce radicals. Radicals are intermediates in many chemical reactions, more so than is apparent from the balanced equations. Radicals are important in combustion, atmospheric chemistry, plasma chemistry and many other chemical processes. A large fraction of natural products is generated by radical-generating enzymes. In living organisms, the radicals superoxide and nitric oxide and their reaction products regulate many processes, such as control of vascular tone and thus blood pressure.
They play a key role in the intermediary metabolism of various biological compounds. Such radicals can be messengers in a process dubbed redox signaling. A radical may be otherwise bound. In chemical equations, radicals are denoted by a dot placed to the right of the atomic symbol or molecular formula as follows: C l 2 → U V 2 C l ⋅ Radical reaction mechanisms use single-headed arrows to depict the movement of single electrons: The homolytic cleavage of the breaking bond is drawn with a'fish-hook' arrow to distinguish from the usual movement of two electrons depicted by a standard curly arrow; the second electron of the breaking bond moves to pair up with the attacking radical electron. Radicals take part in radical addition and radical substitution as reactive intermediates. Chain reactions involving radicals can be divided into three distinct processes; these are initiation and termination. Initiation reactions are those, they may involve the formation of radicals from stable species as in Reaction 1 above or they may involve reactions of radicals with stable species to form more radicals.
Propagation reactions are those reactions involving radicals in which the total number of radicals remains the same. Termination reactions are those reactions resulting in a net decrease in the number of radicals. Two radicals combine to form a more stable species, for example: 2Cl·→ Cl2 Radicals can form by breaking of covalent bonds by homolysis; the homolytic bond dissociation energies abbreviated as "ΔH °" are a measure of bond strength. Splitting H2 into 2H•, for example, requires a ΔH ° of +435 kJ·mol-1, while splitting Cl2 into 2Cl• requires a ΔH ° of +243 kJ·mol-1. For weak bonds, homolysis can be induced thermally. Strong bonds require high energy photons or flames to induce homolysis. Radicals or charged species add to non-radicals to give new radicals; this process is the basis of the radical chain reaction. Being prevalent and a diradical, O2 reacts with many organic compounds to generate radicals together with the hydroperoxide radical; this process is related to rancidification of unsaturated fats.
Radicals may be formed by single-electron oxidation or reduction of an atom or molecule. These redox reactions occur in electrochemical cells and in ionization chambers of mass spectrometers. Although radicals are short-lived due to their reactivity, there are long-lived radicals; these are categorized as follows: The prime example of a stable radical is molecular dioxygen. Another common example is nitric oxide. Organic radicals can be long lived if they occur in a conjugated π system, such as the radical derived from α-tocopherol. There are hundreds of examples of thiazyl radicals, which show low reactivity and remarkable thermodynamic stability with only a limited extent of π resonance stabilization. Persistent radical compounds are those whose longevity is due to steric crowding around the radical center, which makes it physically difficult for the radical to react with another molecule. Examples of these include Gomberg's triphenylmethyl radical, Fremy's salt, such as TEMPO, TEMPOL, nitronyl nitroxides, azephenylenyls and radicals derived from PTM and TTM.
Persistent radicals are generated in great quantity during combustion, "may be responsible for the oxidative stress resulting in cardiopulmonary disease and cancer, attributed to exposure to airborne fine particles". Gomberg's free radical can be generated by following reaction in lab - 3C-Cl + Ag === 3C• + AgCl The reason for persistivity of free radicals is either the delocalisation of unpaired electron or the unavailability of unpaired electron to other species due to the screening of neighbouring atoms/groups. Diradicals are molecules containing two radical centers. Multiple radical centers can exist in a molecule. Atmospheric oxygen exists as a diradical in its ground state as triplet oxygen; the low reactivity of atmospheric oxygen is due to its diradical state. Non-radical states of dioxygen are less stable tha
Biosynthesis
Biosynthesis is a multi-step, enzyme-catalyzed process where substrates are converted into more complex products in living organisms. In biosynthesis, simple compounds are modified, converted into other compounds, or joined together to form macromolecules; this process consists of metabolic pathways. Some of these biosynthetic pathways are located within a single cellular organelle, while others involve enzymes that are located within multiple cellular organelles. Examples of these biosynthetic pathways include the production of lipid membrane components and nucleotides. Biosynthesis is synonymous with anabolism; the prerequisite elements for biosynthesis include: precursor compounds, chemical energy, catalytic enzymes which may require coenzymes. These elements create the building blocks for macromolecules; some important biological macromolecules include: proteins, which are composed of amino acid monomers joined via peptide bonds, DNA molecules, which are composed of nucleotides joined via phosphodiester bonds.
Biosynthesis occurs due to a series of chemical reactions. For these reactions to take place, the following elements are necessary: Precursor compounds: these compounds are the starting molecules or substrates in a reaction; these may be viewed as the reactants in a given chemical process. Chemical energy: chemical energy can be found in the form of high energy molecules; these molecules are required for energetically unfavorable reactions. Furthermore, the hydrolysis of these compounds drives a reaction forward. High energy molecules, such as ATP, have three phosphates; the terminal phosphate is split off during hydrolysis and transferred to another molecule. Catalytic enzymes: these molecules are special proteins that catalyze a reaction by increasing the rate of the reaction and lowering the activation energy. Coenzymes or cofactors: cofactors are molecules that assist in chemical reactions; these may be metal ions, vitamin derivatives such as NADH and acetyl CoA, or non-vitamin derivatives such as ATP.
In the case of NADH, the molecule transfers a hydrogen, whereas acetyl CoA transfers an acetyl group, ATP transfers a phosphate. In the simplest sense, the reactions that occur in biosynthesis have the following format: Reactant → e n z y m e Product Some variations of this basic equation which will be discussed in more detail are: Simple compounds which are converted into other compounds as part of a multiple step reaction pathway. Two examples of this type of reaction occur during the formation of nucleic acids and the charging of tRNA prior to translation. For some of these steps, chemical energy is required: Precursor molecule + ATP ↽ − − ⇀ product AMP + PP i Simple compounds that are converted into other compounds with the assistance of cofactors. For example, the synthesis of phospholipids requires acetyl CoA, while the synthesis of another membrane component, requires NADH and FADH for the formation the sphingosine backbone; the general equation for these examples is: Precursor molecule + Cofactor → e n z y m e macromolecule Simple compounds that join together to create a macromolecule.
For example, fatty acids join together to form phospholipids. In turn and cholesterol interact noncovalently in order to form the lipid bilayer; this reaction may be depicted as follows: Molecule 1 + Molecule 2 ⟶ macromolecule Many intricate macromolecules are synthesized in a pattern of simple, repeated structures. For example, the simplest structures of lipids are fatty acids. Fatty acids are hydrocarbon derivatives; these fatty acids create larger components, which in turn incorporate noncovalent interactions to form the lipid bilayer. Fatty acid chains are found in two major components of membrane lipids: phospholipids and sphingolipids. A third major membrane component, does not contain these fatty acid units; the foundation of all biomembranes consists of a bilayer structure of phospholipids. The phospholipid molecule is amphipathic; the phospholipid heads interact with each other and aqueous media, while the hydrocarbon tails orient themselves in the center, away from water. These latter interactions drive the bilayer structure that acts as a barrier for molecules.
There are various types of phospholipids. However, the first step in phospholipid synthesis involves the formation of phosphatidate or diacylglycerol 3-phosphate at the endoplasmic reticulum and outer mitochondrial membrane; the synthesis pathway is found below: The pathway starts with glycerol 3-phosphate, which gets converted to lysophosphatidate via the addition of a fatty acid chain provided by acyl coenzyme A. Then, lysophosphatidate is converted to phosphatidate via the addition of another fatty acid chain contributed by a second acyl CoA.
Polymer
A polymer is a large molecule, or macromolecule, composed of many repeated subunits. Due to their broad range of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers, their large molecular mass relative to small molecule compounds produces unique physical properties, including toughness, a tendency to form glasses and semicrystalline structures rather than crystals. The terms polymer and resin are synonymous with plastic; the term "polymer" derives from the Greek word πολύς and μέρος, refers to a molecule whose structure is composed of multiple repeating units, from which originates a characteristic of high relative molecular mass and attendant properties. The units composing polymers derive or conceptually, from molecules of low relative molecular mass.
The term was coined in 1833 by Jöns Jacob Berzelius, though with a definition distinct from the modern IUPAC definition. The modern concept of polymers as covalently bonded macromolecular structures was proposed in 1920 by Hermann Staudinger, who spent the next decade finding experimental evidence for this hypothesis. Polymers are studied in the fields of biophysics and macromolecular science, polymer science. Products arising from the linkage of repeating units by covalent chemical bonds have been the primary focus of polymer science. Polyisoprene of latex rubber is an example of a natural/biological polymer, the polystyrene of styrofoam is an example of a synthetic polymer. In biological contexts all biological macromolecules—i.e. Proteins, nucleic acids, polysaccharides—are purely polymeric, or are composed in large part of polymeric components—e.g. Isoprenylated/lipid-modified glycoproteins, where small lipidic molecules and oligosaccharide modifications occur on the polyamide backbone of the protein.
The simplest theoretical models for polymers are ideal chains. Polymers are of two types: occurring and synthetic or man made. Natural polymeric materials such as hemp, amber, wool and natural rubber have been used for centuries. A variety of other natural polymers exist, such as cellulose, the main constituent of wood and paper; the list of synthetic polymers in order of worldwide demand, includes polyethylene, polystyrene, polyvinyl chloride, synthetic rubber, phenol formaldehyde resin, nylon, polyacrylonitrile, PVB, many more. More than 330 million tons of these polymers are made every year. Most the continuously linked backbone of a polymer used for the preparation of plastics consists of carbon atoms. A simple example is polyethylene. Many other structures do exist. Oxygen is commonly present in polymer backbones, such as those of polyethylene glycol, DNA. Polymerization is the process of combining many small molecules known as monomers into a covalently bonded chain or network. During the polymerization process, some chemical groups may be lost from each monomer.
This happens in the polymerization of PET polyester. The monomers are terephthalic acid and ethylene glycol but the repeating unit is —OC—C6H4—COO—CH2—CH2—O—, which corresponds to the combination of the two monomers with the loss of two water molecules; the distinct piece of each monomer, incorporated into the polymer is known as a repeat unit or monomer residue. Laboratory synthetic methods are divided into two categories, step-growth polymerization and chain-growth polymerization; the essential difference between the two is that in chain growth polymerization, monomers are added to the chain one at a time only, such as in polyethylene, whereas in step-growth polymerization chains of monomers may combine with one another directly, such as in polyester. Newer methods, such as plasma polymerization do not fit neatly into either category. Synthetic polymerization reactions may be carried out without a catalyst. Laboratory synthesis of biopolymers of proteins, is an area of intensive research. There are three main classes of biopolymers: polysaccharides and polynucleotides.
In living cells, they may be synthesized by enzyme-mediated processes, such as the formation of DNA catalyzed by DNA polymerase. The synthesis of proteins involves multiple enzyme-mediated processes to transcribe genetic information from the DNA to RNA and subsequently translate that information to synthesize the specified protein from amino acids; the protein may be modified further following translation in order to provide appropriate structure and functioning. There are other biopolymers such as rubber, suberin and lignin. Occurring polymers such as cotton and rubber were familiar materials for years before synthetic polymers such as polyethene and perspex appeared on the market. Many commercially important polymers are synthesized by chemical modification of occurring polymers. Prominent examples inclu
Actinide
The actinide or actinoid series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium. Speaking, both actinium and lawrencium have been labeled as group 3 elements, but both elements are included in any general discussion of the chemistry of the actinide elements. Actinium is the more omitted of the two, because its placement as a group 3 element is somewhat more common in texts and for semantic reasons: since "actinide" means "like actinium", it has been argued that actinium cannot logically be an actinide, but IUPAC acknowledges its inclusion based on common usage; the actinide series derives its name from the first element in actinium. The informal chemical symbol An is used in general discussions of actinide chemistry to refer to any actinide. All but one of the actinides are f-block elements, with the exception being either actinium or lawrencium; the series corresponds to the filling of the 5f electron shell, although actinium and thorium lack any 5f electrons, curium and lawrencium have the same number as the preceding element.
In comparison with the lanthanides mostly f-block elements, the actinides show much more variable valence. They all have large atomic and ionic radii and exhibit an unusually large range of physical properties. While actinium and the late actinides behave to the lanthanides, the elements thorium and uranium are much more similar to transition metals in their chemistry, with neptunium and plutonium occupying an intermediate position. All actinides are release energy upon radioactive decay; these are used in nuclear weapons. Uranium and thorium have diverse current or historical uses, americium is used in the ionization chambers of most modern smoke detectors. Of the actinides, primordial thorium and uranium occur in substantial quantities; the radioactive decay of uranium produces transient amounts of actinium and protactinium, atoms of neptunium and plutonium are produced from transmutation reactions in uranium ores. The other actinides are purely synthetic elements. Nuclear weapons tests have released at least six actinides heavier than plutonium into the environment.
In presentations of the periodic table, the lanthanides and the actinides are customarily shown as two additional rows below the main body of the table, with placeholders or else a selected single element of each series shown in a single cell of the main table, between barium and hafnium, radium and rutherfordium, respectively. This convention is a matter of aesthetics and formatting practicality. Like the lanthanides, the actinides form a family of elements with similar properties. Within the actinides, there are two overlapping groups: transuranium elements, which follow uranium in the periodic table—and transplutonium elements, which follow plutonium. Compared to the lanthanides, which are found in nature in appreciable quantities, most actinides are rare; the majority of them do not occur in nature, of those that do, only thorium and uranium do so in more than trace quantities. The most abundant or synthesized actinides are uranium and thorium, followed by plutonium, actinium, protactinium and curium.
The existence of transuranium elements was suggested by Enrico Fermi based on his experiments in 1934. However though four actinides were known by that time, it was not yet understood that they formed a family similar to lanthanides; the prevailing view that dominated early research into transuranics was that they were regular elements in the 7th period, with thorium and uranium corresponding to 6th-period hafnium and tungsten, respectively. Synthesis of transuranics undermined this point of view. By 1944 an observation that curium failed to exhibit oxidation states above 4 prompted Glenn Seaborg to formulate a so-called "actinide hypothesis". Studies of known actinides and discoveries of further transuranic elements provided more data in support of this point of view, but the phrase "actinide hypothesis" remained in active use by scientists through the late 1950s. At present, there are two major methods of producing isotopes of transplutonium elements: irradiation of the lighter elements with either neutrons or accelerated charged particles.
The first method is most important for applications, as only neutron irradiation using nuclear reactors allows the production of sizeable amounts of synthetic actinides. The advantage of the second method is that elements heavier than plutonium, as well as neutron-deficient isotopes, can be obtained, which are not formed during neutron irradiation. In 1962–1966, there were attempts in the United States to produce transplutonium isotopes using a series of six underground nuclear explosions. Small samples of rock were extracted from the blast area after the test to study the explosion products, but no isotopes with mass number greater than 257
Salt (chemistry)
In chemistry, a salt is an ionic compound that can be formed by the neutralization reaction of an acid and a base. Salts are composed of related numbers of cations and anions so that the product is electrically neutral; these component ions can be inorganic, such as organic, such as acetate. Salts can be classified in a variety of ways. Salts that produce hydroxide ions when dissolved in water are called alkali salts. Salts that produce acidic solutions are acidic salts. Neutral salts are those salts that are neither basic. Zwitterions contain an anionic and a cationic centres in the same molecule, but are not considered to be salts. Examples of zwitterions include amino acids, many metabolites and proteins. Solid salts tend to be transparent. In many cases, the apparent opacity or transparency are only related to the difference in size of the individual monocrystals. Since light reflects from the grain boundaries, larger crystals tend to be transparent, while the polycrystalline aggregates look like white powders.
Salts exist in many different colors, which arise either from the cations. For example: sodium chromate is yellow by virtue of the chromate ion potassium dichromate is orange by virtue of the dichromate ion cobalt nitrate is red owing to the chromophore of hydrated cobalt. copper sulfate is blue because of the copper chromophore potassium permanganate has the violet color of permanganate anion. Nickel chloride is green of sodium chloride, magnesium sulfate heptahydrate are colorless or white because the constituent cations and anions do not absorb in the visible part of the spectrumFew minerals are salts because they would be solubilized by water. Inorganic pigments tend not to be salts, because insolubility is required for fastness; some organic dyes are salts, but they are insoluble in water. Different salts can elicit all five basic tastes, e.g. salty, sour and umami or savory. Salts of strong acids and strong bases are non-volatile and odorless, whereas salts of either weak acids or weak bases may smell like the conjugate acid or the conjugate base of the component ions.
That slow, partial decomposition is accelerated by the presence of water, since hydrolysis is the other half of the reversible reaction equation of formation of weak salts. Many ionic compounds exhibit significant solubility in water or other polar solvents. Unlike molecular compounds, salts dissociate in solution into cationic components; the lattice energy, the cohesive forces between these ions within a solid, determines the solubility. The solubility is dependent on how well each ion interacts with the solvent, so certain patterns become apparent. For example, salts of sodium and ammonium are soluble in water. Notable exceptions include potassium cobaltinitrite. Most nitrates and many sulfates are water-soluble. Exceptions include barium sulfate, calcium sulfate, lead sulfate, where the 2+/2− pairing leads to high lattice energies. For similar reasons, most alkali metal carbonates are not soluble in water; some soluble carbonate salts are: potassium carbonate and ammonium carbonate. Salts are characteristically insulators.
Molten salts or solutions of salts conduct electricity. For this reason, liquified salts and solutions containing dissolved salts are called electrolytes. Salts characteristically have high melting points. For example, sodium chloride melts at 801 °C; some salts with low lattice energies are liquid near room temperature. These include molten salts, which are mixtures of salts, ionic liquids, which contain organic cations; these liquids exhibit unusual properties as solvents. The name of a salt starts with the name of the cation followed by the name of the anion. Salts are referred to only by the name of the cation or by the name of the anion. Common salt-forming cations include: Ammonium NH+4 Calcium Ca2+ Iron Fe2+ and Fe3+ Magnesium Mg2+ Potassium K+ Pyridinium C5H5NH+ Quaternary ammonium NR+4, R being an alkyl group or an aryl group Sodium Na+ Copper Cu2+Common salt-forming anions include: Acetate CH3COO− Carbonate CO2−3 Chloride Cl− Citrate HOC2 Cyanide C≡N− Fluoride F− Nitrate NO−3 Nitrite NO−2 Oxide O2− Phosphate PO3−4 Sulfate SO2−4 Salts with varying number of hydrogen atoms, with respect to the parent acid, replaced by cations can be referred to as monobasic, dibasic or tribasic salts: Sodium phosphate monobasic Sodium phosphate dibasic Sodium phosphate tribasic Salts are formed by a chemical reaction between: A base and an acid, e.g. NH3 + HCl → NH4Cl A metal and an acid, e.g. Mg + H2SO4 → MgSO4 + H2 A metal and a non-metal, e.g. Ca + Cl2 → CaCl2 A base and an a
