Specifically, they found that a 10-fold increase in applied sulfur within 1 kilometer (0.62 miles) of the child's residence during the year before the respiratory evaluation was associated with a 3.5-fold increased risk for asthma medication use and double the risk for respiratory symptoms, such as wheezing and shortness of breath, according to Berkeley News. Are \( _{28}^{63}\textrm{X}\)and \( _{29}^{62}\textrm{X}\) isotopes of the same element? Neutral atoms have the same number of electrons and protons. S-32 is the most common isotope with an abundance of 95.02%. Interestingly, some bacteria have evolved to make use of oxidized sulfur , sulfate, as an electron acceptor during respiration. Scientists discover 1st 'neutron-rich' isotope of uranium since 1979. The specification of Z, A, and the chemical symbol (a one- or two-letter abbreviation of the elements name, say Sy) in the form AZSy identifies an isotope adequately for most purposes. The C-13 and S-34 of coexisting carbonates and sulfides can be used to determine the pH and oxygen fugacity of the ore-bearing fluid during . 13.3: Isotopes in Mass Spectrometry - Chemistry LibreTexts The atomic number of each element increases by one, reading from left to right. Download our free Periodic Table app for mobile phones and tablets. $('#pageFiles').css('display', 'none'); In 1961 the isotope carbon-12 was selected to replace oxygen as the standard relative to which the atomic . NASA has flown a different type of mass spectrometer to Mars to search for molecules and life. Phosphorus-32 - Wikipedia The biogenic compound dimethylsulfide (DMS) is produced from the cleavage of dimethylsufonoprioponate, an osmotic regulatory compound produced by plankton in the ocean. atomic mass of element = [(mass of isotope 1 in amu) (mass fraction of isotope 1)] + [(mass of isotope 2) (mass fraction of isotope 2)] + , German for wolf stone because it interfered with the smelting of tin and was thought to devour the tin. Thus, even British journals like, Excuse you! Figure \(\PageIndex{1}\): The three most stable isotopes of . Thick black anoxic sediments can be accompanied by a putrid smell which is unique to reduced sulfur. CAS number The temperature at which the solidliquid phase change occurs. Psalm 11:6. Sulfur has four naturally occurring isotopes: 32 S, 33 S, 34 S, and 36 S. The 32 S and 34 S isotopes are most commonly used for isotope ratio analysis. Relative atomic mass 16.4C: Sulfur - Allotropes - Chemistry LibreTexts Sulfur dioxide was used to fumigate homes from ancient times, a practice which continued well into the 19th century. The percentage of the world reserves located in the country with the largest reserves. Stephanie Pappas is a contributing writer for Live Science, covering topics ranging from geoscience to archaeology to the human brain and behavior. A vertical column in the periodic table. Note that the lighter 35Cl+ ions are deflected more than the heavier 37Cl+ ions. Common reference compound: (NH 4) 2 SO 4 /D 2 O, saturated. Sulfur occurs naturally as the element, often in volcanic areas. Three nuclei with one proton are known that contain 0, 1, and 2 neutrons, respectively. Not all the atoms of an element need have the same number of neutrons in their nuclei. Articles from Britannica Encyclopedias for elementary and high school students. Because most elements exist as mixtures of several stable isotopes, the atomic mass of an element is defined as the weighted average of the masses of the isotopes. (b) Each peak in the mass spectrum corresponds to an ion with a particular mass-to-charge ratio. Imagine warmer temperatures followed by greater biological activity resulting in more DMS to the atmosphere. Sulfur - Wikipedia For example, small amounts of hydrogen sulfide can be metabolized, but higher concentrations can quickly cause death from respiratory paralysis. Although the Environmental Protection Agency (EPA) has labeled elemental sulfur as generally safe, studies have shown that this type of pesticide is a respiratory irritant to farmworkers. This is calculated by combining the scores for crustal abundance, reserve distribution, production concentration, substitutability, recycling rate and political stability scores. The . In such cases, chemists usually define a standard by arbitrarily assigning a numerical value to one of the quantities, which allows them to calculate numerical values for the rest. The number of protons in an atom. How many protons, neutrons, and electrons does a neutral atom of each contain? Although the difference in mass is small, it is extremely important because it is the binding energy of the nucleus. Simple: a small fraction - about 1.1% - of all carbon atoms in nature are actually the 13 C rather than the 12 C isotope. The value of 12.01 is shown under the symbol for C in the periodic table although without the abbreviation amu, which is customarily omitted. That is enough sulfur to make two additional moons. What are the isotopes of sulfur? The temperature at which the solidliquid phase change occurs. Medium = substitution is possible but there may be an economic and/or performance impact, Low = substitution is possible with little or no economic and/or performance impact, If you wish to use the Images in a manner not permitted by these terms and conditions please contact the Publishing Services Department. . D Check to make sure that your answer makes sense. It provides a measure of how difficult it is to extend a material, with a value given by the ratio of tensile strength to tensile strain. With nearly 100 million tons of waste sulfur produced a year, the 10 percent not used in sulfuric acid production comes out to a not-insignificant 10 million tons a year. It is taken up as sulfate from the soil (or seawater) by plants and algae. The relative masses of atoms are reported using the atomic mass unit (amu), which is defined as one-twelfth of the mass of one atom of carbon-12, with 6 protons, 6 neutrons, and 6 electrons. Electron configuration [Why does my textbook use "amu" instead of "u"?] Other than 35S, the radioactive isotopes of sulfur are all comparatively short-lived. They've found a way to turn waste sulfur into plastic, which in turn can be used in thermal imaging devices and lithium-sulfur batteries. This atomic number is ordinarily given the symbol Z. Sulfur dioxide in the atmosphere comes mostly from fossil-fuel power plants and is one of the primary causes of acid rain. Sulfur is used in the vulcanisation of black rubber, as a fungicide and in black gunpowder. A horizontal row in the periodic table. In most cases, the symbols for the elements are derived directly from each elements name, such as C for carbon, U for uranium, Ca for calcium, and Po for polonium. Their findings were published in August 2017 in the journal Environmental Health Perspectives. The abundance of the two isotopes can be determined from the heights of the peaks. Elemental sulfur is used as an electrical insulator. Where more than one isotope exists, the value given is the abundance weighted average. Maybe this is why sulfur has such a bad reputation. B Calculate the mass number of each isotope by adding together the numbers of protons and neutrons. Sulfur ( 16 S) has 23 known isotopes with mass numbers ranging from 27 to 49, four of which are stable: 32 S (95.02%), 33 S (0.75%), 34 S (4.21%), and 36 S (0.02%). The higher the value, the larger risk there is to supply. She has taught science courses at the high school, college, and graduate levels. Sulfide Trace Element Signatures and S- and Pb-Isotope Geochemistry of It is used to make sulfuric acid. Half-life, decay mode, nuclear spin, and isotopic composition is sourced in: Learn how and when to remove this template message, "Standard atomic weights of the elements 2021 (IUPAC Technical Report)", "The NUBASE2016 evaluation of nuclear properties", "The AME2016 atomic mass evaluation (II). Sulfur and sulfate are non-toxic. $('#attachments').css('display', 'none'); The differences between minerals can be used to estimate the temperature of equilibration. "It was completely soluble in liquid sulfur.". Hydrogen is a case in point. Recall from Section 1.5 that the nuclei of most atoms contain neutrons as well as protons. When you purchase through links on our site, we may earn an affiliate commission. But it leads to hills of elemental sulfur piling up in refineries. The isotope sulfur-35 is used in various sulfur-containing compounds as a radioactive tracer for many biological studies, for example, . The study authors urgently call for more research to confirm these findings in the hope that it will lead to changes in regulations and application methods to limit respiratory harm on nearby residents. Sulfur also occurs in petroleum crude oil and natural gas. ThoughtCo. Although they do not emit radiation, their unique properties enable them to be used in a broad variety of applications, including water and soil management, environmental studies, nutrition assessment studies and forensics. This has traditionally been a major source for human use. Sulfur dioxide is produced when coal and unpurified oil are burned. These compounds can further oxidize and rain out as sulfuric or sulfurous acid. Industry is one place you are almost certain to find sulfur or more importantly sulfuric acid which is used in processes ranging from fertilizer production to oil refining. Determine the number of protons, neutrons, and electrons in a neutral atom of each isotope: Both technetium-97 and americium-240 are produced in nuclear reactors. The tendency of an atom to attract electrons towards itself, expressed on a relative scale. If the stench is of rotten eggs, it might just be the fault of sulfur. Isotopes The majority of this is as the . You are probably talking about sulfur.elemental sulfur exists in a multitude of allotropes. Melting point At the end of their ropes, the researchers decided just to melt the stuff. Sulfur dioxide in the atmosphere comes mostly from fossil-fuel power plants and is one of the primary causes of acid rain. The sum of the oxidation states within a compound or ion must equal the overall charge. So A is the mass number, which is equal to the number of protons, that's the atomic number which we symbolized by Z, plus the number of neutrons. $('#commentText').css('display', 'none'); For example, the ratio of the masses of 1H (hydrogen) and 2H (deuterium) is actually 0.500384, rather than 0.49979 as predicted from the numbers of neutrons and protons present. Tables, graphs, and references", https://en.wikipedia.org/w/index.php?title=Isotopes_of_sulfur&oldid=1149061185, This page was last edited on 9 April 2023, at 23:48. Taylor, "Isotopic Compositions of the Elements 1997," J. Phys. Isotopes of Sulfur - an overview | ScienceDirect Topics Copper, an excellent conductor of heat, has two isotopes: 63Cu and 65Cu. In a neutral atom, the number of electrons equals the number of protons. Every chemical element has one or more isotopes. A large fraction of the chemical elements that occur naturally on the earth's surface are essential to the structure and metabolism of living things. The masses of the other elements are determined in a similar way. These values were determined using several different methods. What isotopic standard is used for determining the mass of an atom? By measuring the relative deflections of the ions, chemists can determine their mass-to-charge ratios and thus their masses. The atomic number of each element increases by one, reading from left to right. 0.75% of natural sulfur is sulfur . According to the researchers, one idea is to switch to "wettable" powders. Sulfur - Protons - Neutrons - Electrons - Electron Configuration We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Isotopes of sulfur - Wikipedia It is used in the vulcanization of rubber. Other English texts kept the 'ph' spelling. (Authors who do not wish to use symbols sometimes write out the element name and mass numberhydrogen-1 and uranium-235 in the examples above.). Atomic radius, non-bonded The most common decay mode for isotopes lighter than the stable isotopes is + decay to nitrogen, and the most common mode after is decay to fluorine. Many elements other than carbon have more than one stable isotope; tin, for example, has 10 isotopes. The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. Please be sure you are familiar with the topics discussed in Essential Skills 1 (Section 1.7) before proceeding to the Numerical Problems. General form to write an isotope: where, A = Atomic mass of the element. Helmenstine, Anne Marie, Ph.D. "Sulfur Facts." It has the atomic number 1. When sulfide minerals are precipitated, isotopic equilibration among solids and liquid may cause small differences in the S-34 values of co-genetic minerals. A The atomic mass is the weighted average of the masses of the isotopes. Welcome to "A Visual Interpretation of The Table of Elements", the most striking version of the periodic table on the web. This is where the artist explains his interpretation of the element and the science behind the picture. Or it could be from the Sanskrit "shulbari," which means "enemy of copper." Most sulfur is, however, used in the production of sulfuric acid, which is perhaps the most important chemical manufactured by western civilisations. Values are given for typical oxidation number and coordination. Sulfur has 21 known isotopes ranging from S-27 to S-46 and S-48. Isotopes of germanium - Wikipedia Identify each element, represented by X, that have the given symbols. Professor of Chemistry, Rutgers University, New Brunswick, New Jersey. Use the atomic mass of sulfur from the periodic table and the following atomic masses to determine whether these data are accurate, assuming that these are the only isotopes of sulfur: 31.972071 amu for 32S, 32.971459 amu for 33S, and 33.967867 amu for 34S. And for me, personally, the worst chemistry of all occurs when reduced sulfur imparts a bad (skunky) taste in bottles of wine or beer. The most common isotope is sulfur-32 with 94.99% abundance. Sulfur is an element that is essential for life. Group The next longest-lived radioisotope is sulfur-38, with a half-life of 170 minutes. While every effort has been made to follow citation style rules, there may be some discrepancies. B Multiplying the exact mass of each isotope by the corresponding mass fraction gives the isotopes weighted mass: C The sum of the weighted masses is the atomic mass of bromine is. Identify the element and write symbols for the isotopes. Members of a group typically have similar properties and electron configurations in their outer shell. It turns out that sulfur becomes a polymer a long chain of linked molecules that is the basis for plastics automatically when heated above 320 F (160 C). Biological roles of the elements - Wikipedia The availability of suitable substitutes for a given commodity. We hope that you enjoy your visit to this Site. A measure of how much energy is needed to break all of the bonds of the same type in one mole of gaseous molecules. Germanium (32 Ge) has five naturally occurring isotopes, 70 Ge, 72 Ge, 73 Ge, 74 Ge, and 76 Ge. The technique is conceptually similar to the one Thomson used to determine the mass-to-charge ratio of the electron. The mass of an atom relative to that of carbon-12. Isotopes_of_sulfur - chemeurope.com Isotopes - Chemistry | Socratic Additionally, the combination of burning coal and fog creates smog in many industrial cities causing respiratory problems among the locals. For some atoms like carbon, oxygen, hydrogen, nitrogen, and sulfur, the M mi of these elements is exactly the same as the mass of its natural isotope, which is the lightest one. Sulfur-32 accounts for 95% of the element on earth, with sulfur-34 accounting for most of the rest. We will encounter many other examples later in this text. Although reports have been presented on the use of sulfur isotopes to differentiate anthropogenic and natural sources of sulfur dioxide, it would not appear that the sulfur isotopes have been . Thankfully next week's element is a lot less odiforous. Atoms of the same element with different numbers of neutrons. So, where does the "smell of hell" come from in anoxic sediments. Hello, this week stinky sediments, skunks and the smell of hell. "It was a tremendous challenge, and we were the first crazy people to get really serious about it," Pyun told Live Science. Atomic number Block In no event shall the RSC be liable for any damages including, without limitation, indirect or consequential damages, or any damages whatsoever arising from use or loss of use, data or profits, whether in action of contract, negligence or other tortious action, arising out of or in connection with the use of the material available from this Site. But scientifically speaking, "sulfur" is correct, according to the International Union of Pure and Applied Chemistry, the organization whose job it is to determine these things. Please refer to the appropriate style manual or other sources if you have any questions. Rutherfords nuclear model of the atom helped explain why atoms of different elements exhibit different chemical behavior. Minerals | Free Full-Text | Stable Isotope Imprints during Pyrite Sulfur makes up almost 3 percent of the Earth's mass, according to Chemicool. [2] In the atomic symbol of 32 S, the number 32 refers to the mass of each sulfur atom in Daltons, the result of the 16 protons and 16 neutrons of 1 Dalton each that make up the sulfur nucleus. The average human contains 140 grams and takes in about 1 gram a day, mainly in proteins. It's in the third row and sixth column on the periodic table. The RSC makes no representations whatsoever about the suitability of the information contained in the documents and related graphics published on this Site for any purpose. Sulfur is a component of gunpowder. In such cases we would ask you to sign a Visual Elements licence agreement, tailored to the specific use you propose. The extent of the deflection depends on the mass-to-charge ratio of the ion. New York, The volatility and low solubility of DMS results in some 20 Tg (10^12) of sulfur emitted to the atmosphere annually. First, electrons are removed from or added to atoms or molecules, thus producing charged particles called ions. Which could be good news for the environment. The extent to which the ions are deflected by the magnetic field depends on their relative mass-to-charge ratios. The transition of a substance directly from the solid to the gas phase without passing through a liquid phase. An atom is first identified and labeled according to the number of protons in its nucleus. The great importance of the atomic number derives from the observation that all atoms with the same atomic number have nearly, if not precisely, identical chemical properties. The identity of an element is defined by its atomic number (Z)The number of protons in the nucleus of an atom of an element., the number of protons in the nucleus of an atom of the element. The IUPAC formally adopted the 'f' spelling in 1990. Elemental sulfur was once commercially recovered from wells by the Frasch process. That was the only question I needed to ask a geologist colleague of mine about the sediment she was trying to understand. The town of, Wait, what's up with that spelling, anyway? In addition to the mineralization and alteration features, trace elements, lead and sulfur isotope signatures of sulfide minerals from porphyry copper, base metal and gold-base metal . Sulfites are used to bleach paper and as preservatives for many foodstuffs. It is insoluble in water but soluble in carbon disulfide. Determine the number of protons, neutrons, and electrons in the neutral atoms of each. Hydrogen sulfide quickly deadens the sense of smell. Data, 27:127585 (1995). I'm Chris Smith, thank you for listening and goodbye. Specific heat capacity is the amount of energy needed to change the temperature of a kilogram of a substance by 1 K. A measure of the stiffness of a substance. But sulfur occurs frequently in compounds in nature, usually as a stinky, yellow mineral associated with hot springs and volcanoes, perhaps explaining why the authors of the Bible associated it with hellfire and wrath. Ramsay removed all the nitrogen from his sample by repeatedly passing it over heated magnesium. Density is the mass of a substance that would fill 1 cm3 at room temperature. The researchers found that children living within a half-mile from recent elemental sulfur applications had reduced lung function, higher levels of asthma-related symptoms and greater asthma medication use, compared to unexposed children. Pure sulfur has no smell. Thus the tabulated atomic mass of carbon or any other element is the weighted average of the masses of the naturally occurring isotopes. Half of the distance between two unbonded atoms of the same element when the electrostatic forces are balanced. These . Four isotopes are stable: S-32, S-33, S-34 and S-36. Elements have also been named for their properties [such as radium (Ra) for its radioactivity], for the native country of the scientist(s) who discovered them [polonium (Po) for Poland], for eminent scientists [curium (Cm) for the Curies], for gods and goddesses [selenium (Se) for the Greek goddess of the moon, Selene], and for other poetic or historical reasons. It is defined as the equilibrium pressure exerted by the gas produced above a substance in a closed system. "We're only going to produce more sulfur," he said, adding that they refer to sulfur as the garbage of transportation because it is the byproduct of petroleum refining. { "Chapter_1.1:_Chemistry_in_the_Modern_World" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Chapter_1.3:_A_Description_of_Matter" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Chapter_1.4:_A_Brief_History_of_Chemistry" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Chapter_1.5:_The_Atom" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Chapter_1.6:_Isotopes_and_Atomic_Masses" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Chapter_1.7:__The_Mole_and_Molar_Mass" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Chapter_1.8:_Essential_Skills_I" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, { "Chapter_1:_Introduction" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Chapter_2:_Atomic_Structure" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Chapter_3:__The_Periodic_Table" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, [ "article:topic", "hypothesis:yes", "showtoc:yes", "license:ccbyncsa", "authorname:anonymous", "licenseversion:40" ], https://chem.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fchem.libretexts.org%2FCourses%2FHoward_University%2FGeneral_Chemistry%253A_An_Atoms_First_Approach%2FUnit_1%253A__Atomic_Structure%2FChapter_1%253A_Introduction%2FChapter_1.6%253A_Isotopes_and_Atomic_Masses, \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}}}\) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\). Because the masses of all other atoms are calculated relative to the 12C standard, 12C is the only atom listed in Table 1.6.2 whose exact atomic mass is equal to the mass number. Even better, the process is so simple that Pyun and his colleagues call it "cave man chemistry." 2.1: Isotopes and Atomic Mass - Chemistry LibreTexts The isotopes of an element differ only in their atomic mass, which is given by the mass number (A), the sum of the numbers of protons and neutrons. Naturally occurring bromine consists of the two isotopes listed in the following table: A Convert the percent abundances to decimal form to obtain the mass fraction of each isotope. "It didn't want to dissolve," Pyun said. The arrangements of electrons above the last (closed shell) noble gas. Stable isotopes are non-radioactive forms of atoms. In fact, it is precisely the variation in the number of neutrons in the nuclei of atoms that gives rise to isotopes. Members of a group typically have similar properties and electron configurations in their outer shell. For example, naturally occurring carbon is largely a mixture of two isotopes: 98.89% 12C (mass = 12 amu by definition) and 1.11% 13C (mass = 13.003355 amu). Chemistry of Magnesium (Z=12) - Chemistry LibreTexts Skunks take advantage of the foul smell of butyl seleno-mercaptan as a means of defending themselves against their enemies. B For the first isotope, A = 82 protons + 124 neutrons = 206. The lexicon of isotopes includes three other frequently used terms: isotones for isotopes of different elements with the same number of neutrons, isobars for isotopes of different elements with the same mass number, and isomers for isotopes identical in all respects except for the total energy content of the nuclei. A measure of how difficult it is to compress a substance. Isotopes are said to be stable if, when left alone, they show no perceptible tendency to change spontaneously. This refinement is a good thing for preventing sulfur compounds from heading skyward when the fuel is burned, causing acid rain. Table 1.6.2 Properties of Selected Isotopes. In fact sulfuric acid ranks as the most highly produced chemical in the industrialized world. This Site has been carefully prepared for your visit, and we ask you to honour and agree to the following terms and conditions when using this Site. Solution 0.5184 106.9 u = 55.42 u 0.4816 108.9 u = 52.45 u Weighted avge. This involved forcing super-heated steam into the underground deposits to melt the sulfur, so it could be pumped to the surface as a liquid. The nucleus of phosphorus-32 contains 15 protons and 17 neutrons, one more neutron than the most common isotope of phosphorus, phosphorus-31. The simplicity and low cost make it an attractive option for industry, Pyun said. A measure of the propensity of a substance to evaporate.