DOCSLIB.ORG

Detection of Barium and Strontium Ions in Water

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Detection of Barium and Strontium Ions in Water DETECTION OF BARIUM AND STRONTIUM IONS IN WATER UTILIZING FUNCTIONALIZED SILVER NANOPARTICLES _________________________________________ A Thesis Presented to the Honors Tutorial College Ohio University _________________________________________ In Partial Fulfillment of the Requirements for Graduation from the Honors Tutorial College with the Degree of Bachelor of Science in Chemistry _________________________________________ by Ashley Cobbs May 2020 2 This thesis has been approved by The Honors Tutorial College and the Department of Chemistry and Biochemistry _____________________________ Dr. Anthony S. Stender Assistant Professor, Chemistry & Biochemistry Thesis Advisor _____________________________ Dr. Lauren E. H. McMills Associate Professor, Chemistry & Biochemistry Director of Studies _____________________________ Dr. Donal C. Skinner Dean, Honors Tutorial College 3 Abstract Throughout the world, pollutants in water have become commonplace, largely as the result of human activities. Environmental organizations test waterways all over the United States for a wide array of polluting agents, from organic materials found in pesticides, to harmful bacteria, to heavy metals. The standard instrument used to measure the quantity of metals in water samples is an inductively coupled plasma spectroscopy. This specialized instrument requires extensive training and is expensive to purchase, operate, and maintain. As a result, it places a burden on the testing of water samples and can prohibit water from being tested in a timely manner. Therefore, there is a current need for a faster process to evaluate water samples. The overall objective of this study was to assess the viability of utilizing functionalized silver nanoparticles to economically determine the concentrations of cations, specifically barium and strontium ions, in contaminated water samples. The ligands on the nanoparticles selectively bind the ions, which induce a color change in the nanoparticles that is detectable by a UV-Vis spectrophotometer, a relatively cheap analytical instrument. Significant progress towards the practical application of functionalized nanoparticles with environmental samples was made. After the addition of high concentrations of barium and strontium ions, nanoparticle samples shifted color from yellow to pink, signifying the feasibility of bare- eyed detection. Creating samples with a range of ions from 1 mM to 100 mM, a rough detection range for barium and strontium ions were determined. Regression analysis indicated a strong trend between plasmonic resonance absorbance wavelengths and the concentrations of metal ions in water. With these findings, there are many avenues for future work. To name a few, different nanoparticles could be used, the possibility of interfering factors common in water samples should be investigated, and further data at different concentrations of ions could be collected to produce more precise trend lines. 4 Table of Contents Abstract ............................................................................................................................... 3 List of Figures ..................................................................................................................... 6 List of Tables ...................................................................................................................... 8 List of Abbreviations .......................................................................................................... 9 I. Introduction ............................................................................................................... 10 1.1 Impact on Health ..................................................................................................... 10 1.2 Barium and Strontium ............................................................................................. 11 1.3 Instrumentation........................................................................................................ 12 1.3.1 Instrumentation Comparison ............................................................................ 12 1.3.2 Instrumentation Theory .................................................................................... 13 1.4 Research Objectives ................................................................................................ 19 1.4.1 Research Purpose .............................................................................................. 19 1.4.2 Research Benchmarks ....................................................................................... 20 1.5 Nanoparticles ........................................................................................................... 20 1.5.1 General Background ......................................................................................... 20 1.5.2 Plasmonics ........................................................................................................ 21 1.5.3 Binding to Barium and Strontium .................................................................... 23 II. Experimental Methods ............................................................................................... 25 2.1 Water Quality Comparison...................................................................................... 25 2.1.1 Background ....................................................................................................... 25 2.1.2 Instrumentation & Sample Preparation ............................................................ 26 2.2 Nanoparticle Experiments ....................................................................................... 28 2.2.1 Background ....................................................................................................... 28 2.2.2 Instrumentation & Sample Preparation ............................................................ 30 2.2.3 Methods Development ...................................................................................... 32 2.2.4 Final Method..................................................................................................... 34 III. Results & Discussion ................................................................................................. 36 3.1 ICP Experiment, Water Quality Test....................................................................... 36 3.2 Experiment #4, Tris-HCl Study ............................................................................... 42 3.3 Experiment #5, 10 µM versus 10 mM ..................................................................... 43 3.4 Experiment #6, Barium Concentration Range ........................................................ 45 5 3.5 Experiment #7, Red-Shift Trends ............................................................................ 47 3.5.1 Spectra .............................................................................................................. 47 3.5.2 Trend Analysis .................................................................................................. 51 3.6 Experiment #10, Pink Color Change ...................................................................... 54 3.7 Experiment #14, Citrate versus PVP ...................................................................... 58 IV. Conclusion ................................................................................................................. 62 5.1 Concluding Remarks ............................................................................................... 62 5.2 Future Work ............................................................................................................ 63 V. References ................................................................................................................. 66 6 List of Figures Figure 1: Diagram of ICP plasma torch, adapted from Harris’ textbook.14 ............................ 15 Figure 2: Periodic table listing the theoretical detection limits of samples suspended in solution for ICP-OES (in blue text) and ICP-MS (red text). Using instruments with a MS detector are extremely sensitive. Figure adapted from Evans Analytical Group LLC.15 16 Figure 3: Double-beam UV-Vis spectrophotometer adapted from Harris’ textbook.14 .......... 17 Figure 4: A nanoparticle with a localized surface plasmonic resonance induced by an electric field. Figure adapted from Kelly et al.20 .......................................................................... 21 Figure 5: The variable a is the radius of a gold nanosphere and is equivalent to 60 nm while the variable d is the distance between two gold nanospheres and is the independent variable in this figure. (a) illustrates the red-shifting and formation of multiple peaks as the distance between two nanospheres get closer together. Figure adapted from Romero et al.23 ................................................................................................................................ 22 Figure 6: Diagram of how silver nanoparticles bind to a barium ion via thioglycolic acid ligands. In this case, the nanoparticle is silver and is represented by “Ag”. ................... 24 Figure 7: Experiment #4. First time using 10 nm silver nanoparticles in citrate instead of 50 nm and adding 10 mM barium and strontium solutions instead of 10 µM. Experiment performed on April 9th and 12th, 2019. ........................................................................... 43 Figure 8: Experiment #5. Determining the ability for the UV-vis to differentiate
Load more

Recommended publications
  • Strontium-90
    EPA Facts about Strontium-90 What is strontium-90? The most common isotope of strontium is strontium-90. Radioactive strontium-90 is produced when uranium and plutonium undergo fission. Fission The time required for a radioactive substance to is the process in which the nucleus of a lose 50 percent of its radioactivity by decay is radionuclide breaks into smaller parts. Large known as the half-life. Strontium-90 has a half- amounts of radioactive strontium-90 were life of 29 years and emits beta particles of produced during atmospheric nuclear weapons relatively low energy as it decays. Yttrium-90, its tests conducted in the 1950s and 1960s. As a decay product, has a shorter half-life (64 hours) result of atmospheric testing and radioactive than strontium-90, but it emits beta particles of fallout, this strontium was dispersed and higher energy. deposited on the earth. How are people exposed to strontium- 90? What are the uses of strontium-90? Although external exposure to strontium-90 Strontium-90 is used in medical and agricultural from nuclear testing is of minor concern because studies. It is also used in thermoelectric devices environmental concentrations are low, that are built into small power supplies for use strontium in the environment can become part of the food chain. This pathway of exposure in remote locations, such as navigational beacons, remote weather stations, and space became a concern in the 1950s with the advent vehicles. Additionally, strontium-90 is used in of atmospheric testing of nuclear explosives. electron tubes, radioluminescent markers, as a With the suspension of atmospheric testing of radiation source in industrial thickness gauges, nuclear weapons, dietary intake has steadily and for treatment of eye diseases.
    [Show full text]
  • The Chemistry of Strontium and Barium Scales
    Association of Water Technologies October 20 -23, 2010 Reno, NV, USA The Chemistry of Strontium and Barium Scales Robert J. Ferguson and Baron R. Ferguson French Creek Software, Inc. Kimberton, PA 19442 (610) 935-8337 (610) 935-1008 FAX [email protected] [email protected] Abstract New ‘mystery scales’ are being encountered as cooling tower operators increase cycles to new highs, add ‘reuse’ water to the make-up, and utilize new make-up water sources as part of an overall water conservation strategy. Scales rarely, if ever, encountered in the past are emerging as potential problems. This threat of unexpected scale is compounded because most water treatment service companies do not include barium and strontium in their make-up water analyses. Water sources with even as little 0.01 mg/L of Ba (as Ba) can become very scale-forming with respect to barite (BaSO4) when tower concentration ratios are increased and sulfuric acid used for pH control. Make-up waters incorporating reverse osmosis concentrate can also provide a strontium and barium source. In some cases, produced waters are also being used in an effort for greener water use. This paper discusses the chemistry of the barium and strontium based scales barite (BaSO4), celestite (SrSO4), witherite (BaCO3) and strontianite (SrCO3). Conditions for formation and control from a water treater’s perspective are emphasized. Indices for prediction are discussed. Scale Prediction and the Concept of Saturation A majority of the indices used routinely by water treatment chemists are derived from the basic concept of saturation. A water is said to be saturated with a compound (e.g.
    [Show full text]
  • 4. CHEMICAL, PHYSICAL, and RADIOLOGICAL INFORMATION
    STRONTIUM 189 4. CHEMICAL, PHYSICAL, and RADIOLOGICAL INFORMATION 4.1 CHEMICAL IDENTITY Strontium is an alkaline earth element in Group IIA of the periodic table. Because of its high reactivity, elemental (or metallic) strontium is not found in nature; it exists only as molecular compounds with other elements. The chemical information for elemental strontium and some of its compounds is listed in Table 4-1. Radioactive isotopes of strontium (e.g., 89Sr and 90Sr, see Section 4.2) are the primary cause of concern with regard to human health (see Chapter 3). 4.2 PHYSICAL, CHEMICAL, AND RADIOLOGICAL PROPERTIES The physical properties of strontium metal and selected strontium compounds are listed in Table 4-2. The percent occurrence of strontium isotopes and the radiologic properties of strontium isotopes are listed in Table 4-3. Strontium can exist in two oxidation states: 0 and +2. Under normal environmental conditions, only the +2 oxidation state is stable enough to be of practical importance since it readily reacts with both water and oxygen (Cotton and Wilkenson 1980; Hibbins 1997). There are 26 isotopes of strontium, 4 of which occur naturally. The four stable isotopes, 84Sr, 86Sr, 87Sr, and 88Sr, are sometimes referred to as stable strontium. The most important radioactive isotopes, 89Sr and 90Sr, are formed during nuclear reactor operations and during nuclear explosions by the nuclear fission of 235U, 238U, or 239Pu. For example, 235U is split into smaller atomic mass fragments such as 90Sr by a nuclear chain reaction initiated by high energy neutrons of approximately 1 million electron volts (or 1 MeV).
    [Show full text]
  • Strontium-90 and Strontium-89: a Review of Measurement Techniques in Environmental Media
    STRONTIUM-90 AND STRONTIUM-89: A REVIEW OF MEASUREMENT TECHNIQUES IN ENVIRONMENTAL MEDIA Robert J. Budnitz Lawrence Berkeley Laboratory University of California Berkeley, CA 91*720 1. IntroiUiction 2. Sources of Enivronmental Radiostrontium 3. Measurement Considerations a. Introduction b. Counting c. •»Sr/"Sr Separation 4. Chemical Techniques a. Air b. Water c. Milk d. Other Media e. Yttrium Recovery after Ingrowth f. Interferences S- Calibration Techniques h. Quality Control 5. Summary and Conclusions 6. Acknowli'J.jnent 7. References -NOTICE- This report was prepared as an account of worK sponsored by the United States Government. Neither the United States nor the United Slates Atomic Energy Commission, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any wananty, express or implied, or asjumes any legal liabili:y or responsibility for the accuracy, com­ pleteness or usefulness of any Information, apparatus, J product or process disclosed, or represents that its use I would not infringe privately owned rights. Mmh li\ -1- 1. INTRODUCTION There are only two radioactive isotopes SrflO of strontium of significance in radiological measurements in the environment: strontium-89 Avg.jS energy 196-1 k«V and strontium-90. 100 Strontium-90 is the more significant from the point of view of environmental impact. 80 Energy keV 644 This is due mostly to its long half-life % Emission 100 (28.1 years). It is a pure beta emitter with 60 Typ* of only one decay mode, leading to yttrium-90 •mission by emission of a negative beta with HUBX * 40 h S46 keV.
    [Show full text]
  • PUBLIC HEALTH STATEMENT Strontium CAS#: 7440-24-6
    PUBLIC HEALTH STATEMENT Strontium CAS#: 7440-24-6 Division of Toxicology April 2004 This Public Health Statement is the summary External exposure to radiation may occur from chapter from the Toxicological Profile for natural or man-made sources. Naturally occurring strontium. It is one in a series of Public Health sources of radiation are cosmic radiation from space Statements about hazardous substances and their or radioactive materials in soil or building materials. health effects. A shorter version, the ToxFAQs™, is Man-made sources of radioactive materials are also available. This information is important found in consumer products, industrial equipment, because this substance may harm you. The effects atom bomb fallout, and to a smaller extent from of exposure to any hazardous substance depend on hospital waste and nuclear reactors. the dose, the duration, how you are exposed, personal traits and habits, and whether other If you are exposed to strontium, many factors chemicals are present. For more information, call determine whether you’ll be harmed. These factors the ATSDR Information Center at 1-888-422-8737. include the dose (how much), the duration (how _____________________________________ long), and how you come in contact with it. You must also consider the other chemicals you’re This public health statement tells you about exposed to and your age, sex, diet, family traits, strontium and the effects of exposure. lifestyle, and state of health. The Environmental Protection Agency (EPA) identifies the most serious hazardous waste sites in 1.1 WHAT IS STRONTIUM? the nation. These sites make up the National Priorities List (NPL) and are the sites targeted for Strontium is a natural and commonly occurring long-term federal cleanup activities.
    [Show full text]
  • Sequential Isotopic Determination of Plutonium, Strontium, Americium
    Sequential Isotopic Determination of Plutonium, Americium, Uranium, and Strontium in Soil Sample Jeng-Jong Wang, Shing-Fa Fang, and Tzu-Wen Wang Institute of Nuclear Energy Research, Atomic Energy Council, Taiwan, R.O.C. Abstract A procedure is developed to provide sequential analysis of 238Pu, 239/240Pu, 241Am, 238U, and 90Sr in soil sample. Tracers and/or carriers (242Pu, 243Am, 232U, and stable strontium) are added into the soil sample as chemical yield monitors, and then digested and extracted with nitric acid. Plutonium, strontium, americium, and uranium are sequential separated and purified by Dowex ion-exchange resin, EiChroM Sr-resin, EiChroM TRU-resin, and Chelate-100 resin, respectively. 90Sr is measured by Cerenkov counting. The actinides are determined by alpha-particle spectrometer. This method is verified by analyzed the U.S. National Institute of Standard and Technology NRIP2000 soil samples. The analytical results of 241Am, 238Pu, 239/240Pu, 238U, and 90Sr agree with the NIST values within +5.7%, +2.4%, +1.6%, -2.2%, and -2.7%, respectively. According to the traceability limits defined in ANSI N42.22 criteria and measurement traceability to NIST for low-level radionuclides has been demonstrated to be better than 23%, 22%, 22%, 22% and 34% for 241Am, 238Pu, 239/240Pu, 238U, and 90Sr, respectively. Keywords: sequential analysis, NIST, traceability Introduction 238Pu, 239/240Pu, 241Am, 238U, and 90Sr in the environmental samples, such as soil, vegetation, and water, are frequently analyzed for both emergency and routine radiation monitoring. Health physicists use the analytical results of environmental samples to estimate the amount of radioactive material present in the environment, calculating its burden for the radiological workers and the general public.
    [Show full text]
  • Periodic Table 1 Periodic Table
    Periodic table 1 Periodic table This article is about the table used in chemistry. For other uses, see Periodic table (disambiguation). The periodic table is a tabular arrangement of the chemical elements, organized on the basis of their atomic numbers (numbers of protons in the nucleus), electron configurations , and recurring chemical properties. Elements are presented in order of increasing atomic number, which is typically listed with the chemical symbol in each box. The standard form of the table consists of a grid of elements laid out in 18 columns and 7 Standard 18-column form of the periodic table. For the color legend, see section Layout, rows, with a double row of elements under the larger table. below that. The table can also be deconstructed into four rectangular blocks: the s-block to the left, the p-block to the right, the d-block in the middle, and the f-block below that. The rows of the table are called periods; the columns are called groups, with some of these having names such as halogens or noble gases. Since, by definition, a periodic table incorporates recurring trends, any such table can be used to derive relationships between the properties of the elements and predict the properties of new, yet to be discovered or synthesized, elements. As a result, a periodic table—whether in the standard form or some other variant—provides a useful framework for analyzing chemical behavior, and such tables are widely used in chemistry and other sciences. Although precursors exist, Dmitri Mendeleev is generally credited with the publication, in 1869, of the first widely recognized periodic table.
    [Show full text]
  • Strontium-90 (90Sr)
    Strontium-90 (90Sr) July 2002 Fact Sheet 320-076 Division of Environmental Health Office of Radiation Protection WHO DISCOVERED STRONTIUM? Strontium was discovered by Adair Crawford, an Irish chemist, in 1790 while studying the mineral withe rite (BaCO3). When he mixed witherite with hydrochloric acid (HCl) he did not get the results he expected. He assumed that his sample of witherite was contaminated with an unknown mineral, a mineral he named strontianite (SrCO3). Strontium was first isolated by Sir Humphry Davy, a British chemist, in 1808 through the electrolysis of a mixture of strontium chloride (SrCl2) and mercuric oxide (HgO). Today, strontium is obtained from two of its most common ores, celestite (SrSO4) and strontianite (SrCO3), by treating them with hydrochloric acid, forming strontium chloride. The strontium chloride, usually mixed with potassium chloride (KCl), is then melted and electrolyzed, forming strontium and chlorine gas (Cl2). WHAT IS STRONTIUM-90 USED FOR? Many radioactive sealed sources, such as 137Cs, 192Ir, 90Sr, and 125I, are used to treat cancer. Strontium-90 also has some uses in luminous signs, nuclear batteries and industrial gauging. WHERE DOES STRONTIUM-90 COME FROM AND WHERE IS IT FOUND? Stronium-90 is an artificially produced fission by-product resulting from nuclear bombs, above-ground nuclear testing, nuclear reactor operations and nuclear accidents. Strontium-90 is found in the liquid waste stream of nuclear reactors, but is not released to the environment during normal nuclear reactor operations. It is not as likely as cesium-137 to be released as a part of a nuclear reactor accident because it is much less volatile, but it is probably the most dangerous components of the radioactive fallout from a nuclear weapon.
    [Show full text]
  • The Role of Calcium and Strontium As the Most Dominant Elements During
    crystals Article The Role of Calcium and Strontium as the Most Dominant Elements during Combinations of Different Alkaline Earth Metals in the Synthesis of Crystalline Silica-Carbonate Biomorphs Mayra Cuéllar-Cruz 1,2,* and Abel Moreno 2,* 1 Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta S/N, Col. Noria Alta, Guanajuato C.P. 36050, Mexico 2 Instituto de Química, Universidad Nacional Autónoma de México, Av. Universidad 3000, Ciudad Universitaria, Ciudad de México 04510, Mexico * Correspondence: [email protected] (M.C.-C.); [email protected] (A.M.) Received: 22 June 2019; Accepted: 22 July 2019; Published: 24 July 2019 Abstract: The origin of life from the chemical point of view is an intriguing and fascinating topic, and is of continuous interest. Currently, the chemical elements that are part of the different cellular types from microorganisms to higher organisms have been described. However, although science has advanced in this context, it has not been elucidated yet which were the first chemical elements that gave origin to the first primitive cells, nor how evolution eliminated or incorporated other chemical elements to give origin to other types of cells through evolution. Calcium, barium, and strontium silica-carbonates have been obtained in vitro and named biomorphs, because they mimic living organism structures. Therefore, it is considered that these forms can resemble the first structures that were part of primitive organisms. Hence, the objective of this work was to synthesize biomorphs starting with different mixtures of alkaline earth metals—beryllium (Be2+), magnesium (Mg2+), calcium (Ca2+), barium (Ba2+), and strontium (Sr2+)—in the presence of nucleic acids, RNA and genomic DNA (gDNA).
    [Show full text]
  • The Plutonium Challenge-Environmental Issues
    Plutonium Overview The Plutonium Challenge Environmental issues he environmental concerns about plutonium stem from its potentially harmful effects on human health. Unlike many industrial materials whose Ttoxicity was discovered only after years of use, plutonium was immediately recognized as dangerous and as requiring special handling care. Consequently, the health effects on plutonium workers in the United States and the general public have been remarkably benign. Nevertheless, the urgency of the wartime effort and the intensity of the arms race during the early years of the Cold War resulted in large amounts of radioactivity being released into the environment in the United States and Russia. These issues are being addressed now, especially in the United States. Science and international cooperation will play a large role in minimizing the potential health effects on future generations. Environmental Consequences of the Cold War The environmental problems resulting from wartime and Cold War nuclear operations were for the most part kept out of public view during the arms race between the United States and the Soviet Union. On the other hand, concerns over health effects from atmospheric testing were debated during the 1950s, leading to the 1963 Limited Test Ban Treaty, which banned nuclear testing everywhere except underground. The U.S. nuclear weapons complex was not opened for public scrutiny until the late 1980s, following a landmark court decision on mercury cont- amination at the Oak Ridge, Tennessee, facilities of the Department of Energy (DOE) in 1984. In the Soviet Union, all nuclear matters, including environmental problems in the nuclear weapons complex, were kept secret.
    [Show full text]
  • Chemistry of Strontium in Natural Water
    Chemistry of Strontium in Natural Water GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1496 This water-supply paper was printed as separate chapters A-D UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1963 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director The U.S. Geological Survey Library has cataloged this publication as follows: U.S. Geological Survey. Chemistry of strontium in natural water. Washington, U.S. Govt. Print. Off., 1962. iii, 97 p. illus., diagrs., tables. 24 cm. (Its Water-supply paper 1496) Issued as separate chapters A-D. Includes bibliographies. 1. Strontium. 2. Water-Analysis. I. Title. (Series) CONTENTS [The letters in parentheses preceding the titles are those used to designate the separate chapters] Page (A) A survey of analytical methods for the determination of strontium in natural water, by C. Albert Horr____________________________ 1 (B) Copper-spark method for spectrochemical determination of strontirm in water, by Marvin W. Skougstad-______-_-_-_--_~__-___-_- 19 (C) Flame photometric determination of strontium in natural water, by C. Albert Horr_____._____._______________... 33 (D) Occurrence and distribution of strontium in natural water, by Margin W. Skougstad and C. Albert Horr____________.___-._-___-. 55 iii A Survey of Analytical Methods fc r The Determination of Strontium in Natural Water By C. ALBERT HORR CHEMISTRY OF STRONTIUM IN NATURAL rVATER GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1496-A This report concerns work done on behalf of the U.S. Atomic Energy Commission and is published with the permission of the Commission UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1959 UNITED STATES DEPARTMENT OF THE INTERIOR FRED A.
    [Show full text]
  • Reactive Metals Hazards Packaging
    Document No: RXM20172301 Publication Date: January 23, 2017 Revised Date: October 25, 2017 Hazard Awareness & Packaging Guidelines for Reactive Metals General Due to recent events resulting from reactive metals handling, CEI personnel and clients are being updated regarding special packaging guidelines designed to protect the safety of our personnel, physical assets, and customer environments. CEI’s Materials Management staff, in conjunction with guidelines from third party disposal outlets, has approved these alternative packaging guidelines to provide for safe storage and transportation of affected materials. This protocol primarily impacts water reactive or potentially water reactive metals in elemental form, although there are many compounds that are also affected. The alkali metals are a group in the periodic table consisting of the chemical elements lithium, sodium , potassium, rubidium, cesium and francium. This group lies in the s-block of the periodic table as all alkali metals have their outermost electron in an s-orbital. The alkali metals provide the best example of group trends in properties in the periodic table, with elements exhibiting well- characterized homologous behavior. The alkali metals have very similar properties: they are all shiny, soft, highly reactive metals at standard temperature and pressure, and readily lose their outermost electron to form cations with charge +1. They can all be cut easily with a knife due to their softness, exposing a shiny surface that tarnishes rapidly in air due to oxidation. Because of their high reactivity, they must be stored under oil to prevent reaction with air, and are found naturally only in salts and never as the free element.
    [Show full text]