The alkali metals are a group in the periodic table consisting of the chemical elements lithium, potassium, rubidium and francium. This group lies in the s-block of the periodic table of elements as all alkali metals have their outermost electron in an s-orbital: this shared electron configuration results in their having similar characteristic properties. Indeed, the alkali metals provide the best example of group trends in properties in the periodic table, with elements exhibiting well-characterised homologous behaviour; the alkali metals are all shiny, soft reactive metals at standard temperature and pressure and lose their outermost electron to form cations with charge +1. They can all be cut with a knife due to their softness, exposing a shiny surface that tarnishes in air due to oxidation by atmospheric moisture and oxygen; because of their high reactivity, they must be stored under oil to prevent reaction with air, are found only in salts and never as the free elements. Caesium, the fifth alkali metal, is the most reactive of all the metals.
In the modern IUPAC nomenclature, the alkali metals comprise the group 1 elements, excluding hydrogen, nominally a group 1 element but not considered to be an alkali metal as it exhibits behaviour comparable to that of the alkali metals. All the alkali metals react with water, with the heavier alkali metals reacting more vigorously than the lighter ones. All of the discovered alkali metals occur in nature as their compounds: in order of abundance, sodium is the most abundant, followed by potassium, rubidium and francium, rare due to its high radioactivity. Experiments have been conducted to attempt the synthesis of ununennium, to be the next member of the group, but they have all met with failure. However, ununennium may not be an alkali metal due to relativistic effects, which are predicted to have a large influence on the chemical properties of superheavy elements. Most alkali metals have many different applications. One of the best-known applications of the pure elements is the use of rubidium and caesium in atomic clocks, of which caesium atomic clocks are the most accurate and precise representation of time.
A common application of the compounds of sodium is the sodium-vapour lamp, which emits light efficiently. Table salt, or sodium chloride, has been used since antiquity. Lithium finds use as an anode in lithium batteries. Sodium and potassium are essential elements, having major biological roles as electrolytes, although the other alkali metals are not essential, they have various effects on the body, both beneficial and harmful. Sodium compounds have been known since ancient times. While potash has been used since ancient times, it was not understood for most of its history to be a fundamentally different substance from sodium mineral salts. Georg Ernst Stahl obtained experimental evidence which led him to suggest the fundamental difference of sodium and potassium salts in 1702, Henri-Louis Duhamel du Monceau was able to prove this difference in 1736; the exact chemical composition of potassium and sodium compounds, the status as chemical element of potassium and sodium, was not known and thus Antoine Lavoisier did not include either alkali in his list of chemical elements in 1789.
Pure potassium was first isolated in 1807 in England by Sir Humphry Davy, who derived it from caustic potash by the use of electrolysis of the molten salt with the newly invented voltaic pile. Previous attempts at electrolysis of the aqueous salt were unsuccessful due to potassium's extreme reactivity. Potassium was the first metal, isolated by electrolysis; that same year, Davy reported extraction of sodium from the similar substance caustic soda by a similar technique, demonstrating the elements, thus the salts, to be different. Petalite was discovered in 1800 by the Brazilian chemist José Bonifácio de Andrada in a mine on the island of Utö, Sweden. However, it was not until 1817 that Johan August Arfwedson working in the laboratory of the chemist Jöns Jacob Berzelius, detected the presence of a new element while analysing petalite ore; this new element was noted by him to form compounds similar to those of sodium and potassium, though its carbonate and hydroxide were less soluble in water and more alkaline than the other alkali metals.
Berzelius gave the unknown material the name "lithion/lithina", from the Greek word λιθoς, to reflect its discovery in a solid mineral, as opposed to potassium, discovered in plant ashes, sodium, known for its high abundance in animal blood. He named the metal inside the material "lithium". Lithium and potassium were part of the discovery of periodicity, as they are among a series of triads of elements in the same group that were noted by Johann Wolfgang Döbereiner in 1850 as having similar properties. Rubidium and caesium were the first elements to be discovered using the spectroscope, invented in 1859 by Robert Bunsen and Gustav Kirchhoff; the next year, they discovered caesiu
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
In chemistry, an alcohol is any organic compound in which the hydroxyl functional group is bound to a carbon. The term alcohol referred to the primary alcohol ethanol, used as a drug and is the main alcohol present in alcoholic beverages. An important class of alcohols, of which methanol and ethanol are the simplest members, includes all compounds for which the general formula is CnH2n+1OH, it is these simple monoalcohols. The suffix -ol appears in the IUPAC chemical name of all substances where the hydroxyl group is the functional group with the highest priority; when a higher priority group is present in the compound, the prefix hydroxy- is used in its IUPAC name. The suffix -ol in non-IUPAC names typically indicates that the substance is an alcohol. However, many substances that contain hydroxyl functional groups have names which include neither the suffix -ol, nor the prefix hydroxy-. Alcohol distillation originated in India. During 2000 BCE, people of India used. Alcohol distillation was known to Islamic chemists as early as the eighth century.
The Arab chemist, al-Kindi, unambiguously described the distillation of wine in a treatise titled as "The Book of the chemistry of Perfume and Distillations". The Persian physician, alchemist and philosopher Rhazes is credited with the discovery of ethanol; the word "alcohol" is from a powder used as an eyeliner. Al- is the Arabic definite article, equivalent to the in English. Alcohol was used for the fine powder produced by the sublimation of the natural mineral stibnite to form antimony trisulfide Sb2S3, it was considered to be the essence or "spirit" of this mineral. It was used as an antiseptic and cosmetic; the meaning of alcohol was extended to distilled substances in general, narrowed to ethanol, when "spirits" was a synonym for hard liquor. Bartholomew Traheron, in his 1543 translation of John of Vigo, introduces the word as a term used by "barbarous" authors for "fine powder." Vigo wrote: "the barbarous auctours use alcohol, or alcofoll, for moost fine poudre."The 1657 Lexicon Chymicum, by William Johnson glosses the word as "antimonium sive stibium."
By extension, the word came to refer to any fluid obtained by distillation, including "alcohol of wine," the distilled essence of wine. Libavius in Alchymia refers to "vini alcohol vel vinum alcalisatum". Johnson glosses alcohol vini as "quando omnis superfluitas vini a vino separatur, ita ut accensum ardeat donec totum consumatur, nihilque fæcum aut phlegmatis in fundo remaneat." The word's meaning became restricted to "spirit of wine" in the 18th century and was extended to the class of substances so-called as "alcohols" in modern chemistry after 1850. The term ethanol was invented 1892, combining the word ethane with the "-ol" ending of "alcohol". IUPAC nomenclature is used in scientific publications and where precise identification of the substance is important in cases where the relative complexity of the molecule does not make such a systematic name unwieldy. In naming simple alcohols, the name of the alkane chain loses the terminal e and adds the suffix -ol, e.g. as in "ethanol" from the alkane chain name "ethane".
When necessary, the position of the hydroxyl group is indicated by a number between the alkane name and the -ol: propan-1-ol for CH3CH2CH2OH, propan-2-ol for CH3CHCH3. If a higher priority group is present the prefix hydroxy-is used, e.g. as in 1-hydroxy-2-propanone. In cases where the OH functional group is bonded to an sp2 carbon on an aromatic ring the molecule is known as a phenol, is named using the IUPAC rules for naming phenols. In other less formal contexts, an alcohol is called with the name of the corresponding alkyl group followed by the word "alcohol", e.g. methyl alcohol, ethyl alcohol. Propyl alcohol may be n-propyl alcohol or isopropyl alcohol, depending on whether the hydroxyl group is bonded to the end or middle carbon on the straight propane chain; as described under systematic naming, if another group on the molecule takes priority, the alcohol moiety is indicated using the "hydroxy-" prefix. Alcohols are classified into primary and tertiary, based upon the number of carbon atoms connected to the carbon atom that bears the hydroxyl functional group.
The primary alcohols have general formulas RCH2OH. The simplest primary alcohol is methanol, for which R=H, the next is ethanol, for which R=CH3, the methyl group. Secondary alcohols are those of the form RR'CHOH, the simplest of, 2-propanol. For the tertiary alcohols the general form is RR'R"COH; the simplest example is tert-butanol, for which each of R, R', R" is CH3. In these shorthands, R, R', R" represent substituents, alkyl or other attached organic groups. In archaic nomenclature, alcohols can be named as derivatives of methanol using "-carbinol" as the ending. For instance, 3COH can be named trimethylcarbinol. Alcohols have a long history of myriad uses. For simple mono-alcohols, the focus on this article, the following are most important industrial alcohols: methanol for the production of formaldehyde and as a fuel additive ethanol for alcoholic beverages, fuel additive, solvent 1-propanol, 1-butanol, isobutyl alcohol for use as a solvent a
The United States of America known as the United States or America, is a country composed of 50 states, a federal district, five major self-governing territories, various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U. S. is the third most populous country. The capital is Washington, D. C. and the largest city by population is New York City. Forty-eight states and the capital's federal district are contiguous in North America between Canada and Mexico; the State of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west. The State of Hawaii is an archipelago in the mid-Pacific Ocean; the U. S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones. The diverse geography and wildlife of the United States make it one of the world's 17 megadiverse countries.
Paleo-Indians migrated from Siberia to the North American mainland at least 12,000 years ago. European colonization began in the 16th century; the United States emerged from the thirteen British colonies established along the East Coast. Numerous disputes between Great Britain and the colonies following the French and Indian War led to the American Revolution, which began in 1775, the subsequent Declaration of Independence in 1776; the war ended in 1783 with the United States becoming the first country to gain independence from a European power. The current constitution was adopted in 1788, with the first ten amendments, collectively named the Bill of Rights, being ratified in 1791 to guarantee many fundamental civil liberties; the United States embarked on a vigorous expansion across North America throughout the 19th century, acquiring new territories, displacing Native American tribes, admitting new states until it spanned the continent by 1848. During the second half of the 19th century, the Civil War led to the abolition of slavery.
By the end of the century, the United States had extended into the Pacific Ocean, its economy, driven in large part by the Industrial Revolution, began to soar. The Spanish–American War and World War I confirmed the country's status as a global military power; the United States emerged from World War II as a global superpower, the first country to develop nuclear weapons, the only country to use them in warfare, a permanent member of the United Nations Security Council. Sweeping civil rights legislation, notably the Civil Rights Act of 1964, the Voting Rights Act of 1965 and the Fair Housing Act of 1968, outlawed discrimination based on race or color. During the Cold War, the United States and the Soviet Union competed in the Space Race, culminating with the 1969 U. S. Moon landing; the end of the Cold War and the collapse of the Soviet Union in 1991 left the United States as the world's sole superpower. The United States is the world's oldest surviving federation, it is a representative democracy.
The United States is a founding member of the United Nations, World Bank, International Monetary Fund, Organization of American States, other international organizations. The United States is a developed country, with the world's largest economy by nominal GDP and second-largest economy by PPP, accounting for a quarter of global GDP; the U. S. economy is post-industrial, characterized by the dominance of services and knowledge-based activities, although the manufacturing sector remains the second-largest in the world. The United States is the world's largest importer and the second largest exporter of goods, by value. Although its population is only 4.3% of the world total, the U. S. holds 31% of the total wealth in the world, the largest share of global wealth concentrated in a single country. Despite wide income and wealth disparities, the United States continues to rank high in measures of socioeconomic performance, including average wage, human development, per capita GDP, worker productivity.
The United States is the foremost military power in the world, making up a third of global military spending, is a leading political and scientific force internationally. In 1507, the German cartographer Martin Waldseemüller produced a world map on which he named the lands of the Western Hemisphere America in honor of the Italian explorer and cartographer Amerigo Vespucci; the first documentary evidence of the phrase "United States of America" is from a letter dated January 2, 1776, written by Stephen Moylan, Esq. to George Washington's aide-de-camp and Muster-Master General of the Continental Army, Lt. Col. Joseph Reed. Moylan expressed his wish to go "with full and ample powers from the United States of America to Spain" to seek assistance in the revolutionary war effort; the first known publication of the phrase "United States of America" was in an anonymous essay in The Virginia Gazette newspaper in Williamsburg, Virginia, on April 6, 1776. The second draft of the Articles of Confederation, prepared by John Dickinson and completed by June 17, 1776, at the latest, declared "The name of this Confederation shall be the'United States of America'".
The final version of the Articles sent to the states for ratification in late 1777 contains the sentence "The Stile of this Confederacy shall be'The United States of America'". In June 1776, Thomas Jefferson wrote the phrase "UNITED STATES OF AMERICA" in all capitalized letters in the headline of his "original Rough draught" of the Declaration of Independence; this draft of the document did not surface unti
Carbon is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds, it belongs to group 14 of the periodic table. Three isotopes occur 12C and 13C being stable, while 14C is a radionuclide, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity. Carbon is the 15th most abundant element in the Earth's crust, the fourth most abundant element in the universe by mass after hydrogen and oxygen. Carbon's abundance, its unique diversity of organic compounds, its unusual ability to form polymers at the temperatures encountered on Earth enables this element to serve as a common element of all known life, it is the second most abundant element in the human body by mass after oxygen. The atoms of carbon can bond together in different ways, termed allotropes of carbon; the best known are graphite and amorphous carbon. The physical properties of carbon vary with the allotropic form.
For example, graphite is opaque and black while diamond is transparent. Graphite is soft enough to form a streak on paper, while diamond is the hardest occurring material known. Graphite is a good electrical conductor. Under normal conditions, carbon nanotubes, graphene have the highest thermal conductivities of all known materials. All carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form at standard temperature and pressure, they are chemically resistant and require high temperature to react with oxygen. The most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and transition metal carbonyl complexes; the largest sources of inorganic carbon are limestones and carbon dioxide, but significant quantities occur in organic deposits of coal, peat and methane clathrates. Carbon forms a vast number of compounds, more than any other element, with ten million compounds described to date, yet that number is but a fraction of the number of theoretically possible compounds under standard conditions.
For this reason, carbon has been referred to as the "king of the elements". The allotropes of carbon include graphite, one of the softest known substances, diamond, the hardest occurring substance, it bonds with other small atoms, including other carbon atoms, is capable of forming multiple stable covalent bonds with suitable multivalent atoms. Carbon is known to form ten million different compounds, a large majority of all chemical compounds. Carbon has the highest sublimation point of all elements. At atmospheric pressure it has no melting point, as its triple point is at 10.8±0.2 MPa and 4,600 ± 300 K, so it sublimes at about 3,900 K. Graphite is much more reactive than diamond at standard conditions, despite being more thermodynamically stable, as its delocalised pi system is much more vulnerable to attack. For example, graphite can be oxidised by hot concentrated nitric acid at standard conditions to mellitic acid, C66, which preserves the hexagonal units of graphite while breaking up the larger structure.
Carbon sublimes in a carbon arc, which has a temperature of about 5800 K. Thus, irrespective of its allotropic form, carbon remains solid at higher temperatures than the highest-melting-point metals such as tungsten or rhenium. Although thermodynamically prone to oxidation, carbon resists oxidation more than elements such as iron and copper, which are weaker reducing agents at room temperature. Carbon is the sixth element, with a ground-state electron configuration of 1s22s22p2, of which the four outer electrons are valence electrons, its first four ionisation energies, 1086.5, 2352.6, 4620.5 and 6222.7 kJ/mol, are much higher than those of the heavier group-14 elements. The electronegativity of carbon is 2.5 higher than the heavier group-14 elements, but close to most of the nearby nonmetals, as well as some of the second- and third-row transition metals. Carbon's covalent radii are taken as 77.2 pm, 66.7 pm and 60.3 pm, although these may vary depending on coordination number and what the carbon is bonded to.
In general, covalent radius decreases with higher bond order. Carbon compounds form the basis of all known life on Earth, the carbon–nitrogen cycle provides some of the energy produced by the Sun and other stars. Although it forms an extraordinary variety of compounds, most forms of carbon are comparatively unreactive under normal conditions. At standard temperature and pressure, it resists all but the strongest oxidizers, it does not react with hydrochloric acid, chlorine or any alkalis. At elevated temperatures, carbon reacts with oxygen to form carbon oxides and will rob oxygen from metal oxides to leave the elemental metal; this exothermic reaction is used in the iron and steel industry to smelt iron and to control the carbon content of steel: Fe3O4 + 4 C → 3 Fe + 4 COCarbon monoxide can be recycled to smelt more iron: Fe3O4 + 4 CO → 3 Fe + 4 CO2with sulfur to form carbon disulfide and with steam in the coal-gas reaction: C + H2O → CO + H2. Carbon combines with some metals at high temperatures to form metallic carbides, such as the iron carbide cementite in steel and tungsten carbide used as an abrasive and for making hard tips for cutting tools.
The system of carbon allotropes spans a range of extremes: Atomic carbon is a ver
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group on the periodic table, a reactive nonmetal, an oxidizing agent that forms oxides with most elements as well as with other compounds. By mass, oxygen is the third-most abundant element in the universe, after helium. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. Diatomic oxygen gas constitutes 20.8% of the Earth's atmosphere. As compounds including oxides, the element makes up half of the Earth's crust. Dioxygen is used in cellular respiration and many major classes of organic molecules in living organisms contain oxygen, such as proteins, nucleic acids and fats, as do the major constituent inorganic compounds of animal shells and bone. Most of the mass of living organisms is oxygen as a component of water, the major constituent of lifeforms. Oxygen is continuously replenished in Earth's atmosphere by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide.
Oxygen is too chemically reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. Another form of oxygen, ozone absorbs ultraviolet UVB radiation and the high-altitude ozone layer helps protect the biosphere from ultraviolet radiation. However, ozone present at the surface is a byproduct of thus a pollutant. Oxygen was isolated by Michael Sendivogius before 1604, but it is believed that the element was discovered independently by Carl Wilhelm Scheele, in Uppsala, in 1773 or earlier, Joseph Priestley in Wiltshire, in 1774. Priority is given for Priestley because his work was published first. Priestley, called oxygen "dephlogisticated air", did not recognize it as a chemical element; the name oxygen was coined in 1777 by Antoine Lavoisier, who first recognized oxygen as a chemical element and characterized the role it plays in combustion. Common uses of oxygen include production of steel and textiles, brazing and cutting of steels and other metals, rocket propellant, oxygen therapy, life support systems in aircraft, submarines and diving.
One of the first known experiments on the relationship between combustion and air was conducted by the 2nd century BCE Greek writer on mechanics, Philo of Byzantium. In his work Pneumatica, Philo observed that inverting a vessel over a burning candle and surrounding the vessel's neck with water resulted in some water rising into the neck. Philo incorrectly surmised that parts of the air in the vessel were converted into the classical element fire and thus were able to escape through pores in the glass. Many centuries Leonardo da Vinci built on Philo's work by observing that a portion of air is consumed during combustion and respiration. In the late 17th century, Robert Boyle proved. English chemist John Mayow refined this work by showing that fire requires only a part of air that he called spiritus nitroaereus. In one experiment, he found that placing either a mouse or a lit candle in a closed container over water caused the water to rise and replace one-fourteenth of the air's volume before extinguishing the subjects.
From this he surmised that nitroaereus is consumed in both combustion. Mayow observed that antimony increased in weight when heated, inferred that the nitroaereus must have combined with it, he thought that the lungs separate nitroaereus from air and pass it into the blood and that animal heat and muscle movement result from the reaction of nitroaereus with certain substances in the body. Accounts of these and other experiments and ideas were published in 1668 in his work Tractatus duo in the tract "De respiratione". Robert Hooke, Ole Borch, Mikhail Lomonosov, Pierre Bayen all produced oxygen in experiments in the 17th and the 18th century but none of them recognized it as a chemical element; this may have been in part due to the prevalence of the philosophy of combustion and corrosion called the phlogiston theory, the favored explanation of those processes. Established in 1667 by the German alchemist J. J. Becher, modified by the chemist Georg Ernst Stahl by 1731, phlogiston theory stated that all combustible materials were made of two parts.
One part, called phlogiston, was given off when the substance containing it was burned, while the dephlogisticated part was thought to be its true form, or calx. Combustible materials that leave little residue, such as wood or coal, were thought to be made of phlogiston. Air did not play a role in phlogiston theory, nor were any initial quantitative experiments conducted to test the idea. Polish alchemist and physician Michael Sendivogius in his work De Lapide Philosophorum Tractatus duodecim e naturae fonte et manuali experientia depromti described a substance contained in air, referring to it as'cibus vitae', this substance is identical with oxygen. Sendivogius, during his experiments performed between 1598 and 1604, properly recognized that the substance is equivalent to the gaseous byproduct released by the thermal decomposition of potassium nitrate. In Bugaj’s view, the isolation of oxygen and the proper association of the substance to that part of air, required for life, lends sufficient weight to the discovery of oxygen by Sendivogius.