1.0+HISTORY+OF+THE+CHEMISTRY

OF Chttp://www.albalagh.net/kids/science/chemistry.shtml// =|| || || || || ||= == = = = = = = = = = = =Chemistry is the science that deals with the structure and composition of matter and the chemical reactions that are responsible for changing the state and properties of matter. Chemistry is the science of atoms, molecules, crystals and other aggregates of matter and the chemical processes that change their energy and entropy levels as also their structure and composition. Chemistry has been subdivided into distinct disciplines that deal with specific branches of chemistry. The different branches of chemistry deal with different fields of study of matter. Take a look at them. **Different Branches of Chemistry** **Organic Chemistry:** This branch of chemistry deals with the study of the organic matter. The substances that primarily consist of carbon and hydrogen are termed as organic. The discipline that deals with the study of the structure, composition and the chemical properties of organic compounds is known as organic chemistry. This branch also deals with the chemical reactions that are used in the preparation of organic chemical compounds. **Inorganic Chemistry:** It is the branch of chemistry that relates to the structure, composition and behavior of inorganic compounds. All the substances other than the carbon-hydrogen compounds are classified under the group of inorganic substances. Oxides, sulphides and carbonates form the important classes of inorganic compounds. Industrial inorganic chemistry deals with the branch of applied science such as the manufacture of fertilizers, while the descriptive inorganic chemistry deals with the classification of compounds based on their properties. **Analytical Chemistry:** This is a very important branch of chemistry that deals with the analysis of the chemical properties of natural and man-made materials. The study does not restrict itself to any particular type of chemical compounds. Instrumental analysis is a prominent part of modern analytical chemistry. Analytical chemistry primarily deals with the study of the chemicals present in a substance, in what quantity they are, and how they define the chemical properties of the substance. **Physical Chemistry:** This branch of chemistry applies the theories of physics to atoms and subatomic particles. When physical chemistry is applied to the chemical interaction between atoms and subatomic particles, the study is known by the name, quantum mechanics. It is a relatively vast field that deals with intermolecular forces, rates of chemical reactions as well the conductivity of different materials. **Biochemistry:** This discipline of chemistry represents a peep of biology into chemistry. It deals with the structure and behavior of the components of cells and the chemical processes in living beings. The complex and large biomolecules are usually composed of similar units that repeat. The complex molecules are known as polymers and the basic units they are composed of, are known as monomers. Biochemistry deals with the study of cellular constituents like proteins, carbohydrates, lipids, and nucleic acids as also the chemical processes that occur in cells. **Nuclear Chemistry:** It is a popular and one of the very important branches of chemistry that studies radioactivity. It revolves around the study of the nuclear properties of and the chemical processes in radioactive substances. This branch also covers the study of the equipment used for the performance of nuclear processes. The effects of the absorption of radiation, the production and use of radioactive materials and radiotherapy come under this branch of chemistry. Nuclear chemistry also deals with the non-radioactive areas of life.= = = = = =what is chemistry?= = =

= = Chemistry is the study of matter and energy and the interactions between them. This is also the definition for physics, by the way. Chemistry and physics are specializations of **physical science**. Chemistry tends to focus on the properties of substances and the interactions between different types of matter, particularly reactions that involve electrons. Physics tends to focus more on the nuclear part of the atom, as well as the subatomic realm. Really, they are two sides of the same coin. taken from:[] The earliest record of man's interest in chemistry was approximately 3,000 B.C, in the fertile crescent. At that time, chemistry was more an art than a science. Tablets record the first known chemists as women who manufactured perfumes from various substances. Ancient Egyptians produced certain compounds such as those used in mummification. By 1000 B.C, chemical arts included the smelting of metals and the making of drugs, dyes, iron, and bronze. Iron making was also introduced and refinement of lead and mercury was performed. The physical properties of some metals such as copper, zinc, silver, and gold were understood. Many groups of people contributed to these developments--among them were ancient Egyptians, Greeks, Hebrews, Chinese, and Indians. Alchemy It was during this time that the roots of alchemy grew. The Greeks of Egypt are regarded as the forefathers of attempts to change valueless metals into metals of greater value (e.g. iron into gold). In the fourth century B.C, Zosimos the Greek described a substance called Xerion, a metal that supposedly turned other metals into gold. One needed to add a little dab of Xerion to a pile of metal and after two hundred years, the metal would have become gold. This was the extent of the world's knowledge on chemistry. In Europe, it remained so well into the Middle Ages (400-1500 C.E =​ ​= taken from =//[|//http://www.albalagh.net/kids/science/chemistry.shtml**R**//]// = = =

Prehistoric age

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The chemistry started when the human discovered the fire. They use that for transform the matter. The human used that for cooking, extract metals, etc. The first metals that the humans found were the gold and copper. Then they discovered the bronze, a combination of tin and copper. They used that for armor. The use of this combination released the Bronze Age (2500 to 1000BC). This work released the Iron Age (900 to 500BC). In 800BC, the chemical arts was very developed and the Egiptian civilization were very outgoing, specially in the extracting of metal. By 1000 BC, the ancient civilizations were using technologies that would form the basis of the various branches of chemistry. Extracting metal from their ores, making pottery and glazes, fermenting beer and wine, making pigments for cosmetics and painting, extracting chemicals from plants for medicine an d perfume, making cheese, dying cloth, tanning leather, rendering fat into soap, making glass, and making alloys like bronze. Philosophical attempts to explain the nature of matter and its transformations failed. The protoscience of alchemy also failed, but by experimentation and recording the results set the stage for science. Modern chemistry begins to emerge when a clear distinction is made between chemistry and alchemy by Robert Boyle in his work The Sceptical Chymist //(1661). Chemistry then becomes a full-fledged science when Antoine Lavoisier develops his law of conservation of mass, which demands careful measurements and quantitative observations of chemical phenomena. So, while both alchemy and chemistry are concerned with the nature of matter and its transformations, it is only the chemists who apply the scientific method. The **history of chemistry** is intertwined with the history of thermodynamics, especially through the work of Willard Gibbs.[1]

[|taken from http://en.wikipedia.org/wiki/History_of_chemistry] // = =

When most people think of chemistry, they think of lab coats, Bunsen burners, and the cryptic periodic table. They don't usually think of history. But chemistry has a fascinating story to tell.

[|www.chemeritage.org.com]

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​The philosopher´s stone and the rise of alchemy Many people were interested in finding a method that could convert cheaper metals into gold. The material that would help them do this was rumored to exist in what was called the [|philosopher's stone]. This led to the [|protoscience] called [|alchemy]. Alchemy was practiced by many cultures throughout history and often contained a mixture of philosophy, mysticism, and protoscience.[[|citation needed]//] Alchemy not only sought to turn base metals into gold, but especially in a Europe rocked by [|bubonic plague], there was hope that alchemy would lead to the development of medicines to improve people's health. The [|holy grail] of this strain of alchemy was in the attempts made at finding the [|elixir of life], which promised eternal youth. Neither the elixir nor the philosopher's stone were ever found. Also, characteristic of alchemists was the belief that there was in the air an "ether" which breathed life into living things.[//[|citation needed]//] Practitioners of alchemy included [|Isaac Newton], who remained one throughout his life. //

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 * Question:** What Is the Importance of Chemistry?What is the importance of chemistry? Why would you want to learn about chemistry? Chemistry is the study of matter and its interactions with other matter and energy. Here's a look at the importance of chemistry and why you should study it.
 * Answer:** Chemistry has a reputation for being a complicated and boring science, but for the most part, that reputation is undeserved. Fireworks and explosions are based on chemistry, so it's definitely not a boring science. If you take classes in chemistry, you'll apply math and logic, which can make studying chemistry a challenge if you are weak in those areas. However, anyone can understand the basics of how things work... and that's the study of chemistry. In a nutshell, the importance of chemistry is that it explains the world around you.

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Chemistry is a branch of science that has been around for a long time. In fact, chemistry is known to date back to as far as the prehistoric times. Due to the amount of time chemistry takes up on the timeline, the science is split into four general chronological categories. The four categories are: prehistoric times - beginning of the Christian era (black magic), beginning of the Christian era - end of 17th century (alchemy), end of 17th century - mid 19th century (traditional chemistry) and mid 19th century - present (modern chemistry).

taken from [] The History of Chemistry The earliest record of man's interest in chemistry was approximately 3,000 B.C, in the fertile crescent. At that time, chemistry was more an art than a science. Tablets record the first known chemists as women who manufactured perfumes from various substances. Ancient Egyptians produced certain compounds such as tho se used in mummification. By 1000 B.C, chemical arts included the smelting of metals and the making of drugs, dyes, iron, and bronze. Iron making was also introduced and refinement of lead and mercury was performed. The physical properties of some metals such as copper, zinc, silver, and gold were understood. Many groups of people contributed to these developments--among them were ancient Egyptians, Greeks, Hebrews, Chinese, and Indians. Alchemy It was during this time that the roots of alchemy grew. The Greeks of Egypt are regarded as the forefathers of attempts to change valueless metals into metals of greater value (e.g. iron into gold). In the fourth century B.C, Zosimos the Greek described a substance called Xerion, a metal that supposedly turned other metals into gold. One needed to add a little dab of Xerion to a pile of metal and after two hundred years, the metal would have become gold. This was the extent of the world's knowledge on chemistry. In Europe, it remained so well into the Middle Ages (400-1500 C.E). The Coming of Islam Yet at that time, a new empire was forming. Islam was spreading among the people of Arabia. At 632 C.E when Prophet Muhammad, Sall-Allahu alay hi wa sallam, died, nearly all of Arabia had become Muslim. Islam had raised these people from ignorance and darkness into light. The Muslims started to become the most advanced civilization of that time. Though Greeks are shown as wise people who had spectacular achievements in science, Muslims are portrayed as alchemists and transmitters of Greek "wisdom", and Western scientists are shown as the real founders of chemistry, the truth is actually the opposite. It is true that Muslims translated many books and writings of the ancients. However, Muslims soon realized that in the field of chemistry the ancients, mainly being alchemists, dealt primarily with speculation and mystery. Chemistry was not a science before the Muslims. The Muslims invented the scientific method and used it in their research tremendously. The historian Briffault's book, Making of Humanity, has been quoted in Dr. K Ajram's book, The Miracle of Islam Science: "Investigation, accumulation of positive knowledge, minute methods of science and prolonged observation were alien to Greek temperament. These were introduced to Europe by the Arabs. European science owes its existence to the Arabs." Will Durant notes that Muslims "introduced precise observation, controlled experiment, and careful records." Work of Muslims Muslims were not alchemists, but rather they were the world's first true chemists. They produced a variety of compounds useful for the development and advancement of science, culture, industry, and civilization. Muslims invented and/or perfected the processes of distillation, sublimation, crystallization, oxidation, and precipitation. They discovered the process of calcination, which is used to reduce substances to a powdered form. Muslims also discovered many elements with their specific weights. Al-Jabr (d. 815?) discovered 19 elements along with their specific weights. They also were the first to accurately divide the elements. Muslims distinguished between metals and alloys, noting that alloys were only mixtures and not true elements. They originated the synthesis of numerous crucial substances that are essential to the development of chemical sciences. The acid-base principal of chemistry was entirely their development. The pH scale was their invention. Evidence is found in the fact that the word alkali originated from the Arabic word al-kili. They invented the concept of solutions regarding the solubility or insolubility of substances. Industrial Chemistry As industrial chemists, Muslims used advanced techniques for extracting minerals and metals. They perfected glass making and introduced the technology for coloring it with metal oxides. They invented crystal making. They introduced and perfected steel making. They produced dyes and used them in tiles, woodworking, and clothing. They produced a variety of plasters, glazes, and other building compounds. Muslim Spain had roads paved with cement instead of stones and had the world's first street lights. Instruments Muslims invented and/or widely used many chemical instruments that are used until now. They used burners, water baths, bellows, crucibles, distillation apparatuses, scales and weights, beakers, filters, flasks, phials, test tubes, etc. Production of Paper Muslims also perfected the production of paper. This accomplishment is often attributed to the Chinese. Though it is true that the Chinese produced paper, this was done through a tedious process requiring silk. It was the Muslims who instituted chemically-aided paper production. The first paper-manufacturing plant in the Muslim World was opened in Baghdad in 794 C.E. Millions upon millions of books were published wherever this invention arrived. In 891 C.E., Baghdad had over a hundred booksellers. Most mosques had libraries. Many cities also had public libraries. Baghdad at the time of the Mongols' invasion had thirty-six libraries. Private libraries were innumerable; it was common for rich people to have huge collections of books. Princes, according to Will Durant, "in the tenth century might own as many books as could be found in all the libraries of Europe combined." Slowly but steadily, Europeans became accustomed to the luxury of imported paper from the Muslim world. Paper was used in Constantinople by 1100, in Sicily by 1102, in Italy by 1154, in Germany by 1228, and in England by 1309. The production of the many cheap books by Europeans was only possible after the replacement of parchment and silk paper with this new paper. The Western world slowly rose from the coffins of illiteracy in which it had been sinking. Muslims' Writings and Books Muslims' writings and books spurred and strongly stimulated the development of European chemistry. Translated versions of Al-Jabr's works were, according to Mathe, Lavoisier's "bible." Ar-Razi's (d. 925) booklet, Secret of Secrets, is said to be the first known example of a chemistry lab manual. Their books were used in many European schools for many centuries. After the Crusades, especially, as returning Western soldiers told fantastic tales of the Muslim World and all the knowledge that was there, Europeans wanted to learn more and their thirst for knowledge grew. Many books were translated into European languages. Slowly, the Western World acquired the knowledge of Muslims, and began its Renaissance. taken from :http://www.albalagh.net/kids/science/chemistry.shtml ​ ​media type="youtube" key="ogg5cyWxV-4" width="425" height="350" ​

[[image:quimica-11[1].gif]] the chemystry today [[image:quimica-07[1].gif]]
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The earliest record of man's interest in chemistry was approximately 3,000 B.C, in the fertile crescent. At that time, chemistry was more an art than a science. Tablets record the first known chemists as women who manufactured perfumes from various substances. Ancient Egyptians produced certain compounds such as those used in mummification. By 1000 B.C, chemical arts included the smelting of metals and the making of drugs, dyes, iron, and bronze. Iron making was also introduced and refinement of lead and mercury was performed. The physical properties of some metals such as copper, zinc, silver, and gold were understood. Many groups of people contributed to these developments--among them were ancient Egyptians, Greeks, Hebrews, Chinese, and Indians. Alchemy It was during this time that the roots of alchemy grew. The Greeks of Egypt are regarded as the forefathers of attempts to change valueless metals into metals of greater value (e.g. iron into gold). In the fourth century B.C, Zosimos the Greek described a substance called Xerion, a metal that supposedly turned other metals into gold. One needed to add a little dab of Xerion to a pile of metal and after two hundred years, the metal would have become gold. This was the extent of the world's knowledge on chemistry. In Europe, it remained so well into the Middle Ages (400-1500 C.E).

__History of Chemistry __ Chemistry is a branch of science that has been around for a long time. In fact, chemistry is known to date back to as far as the prehistoric times. Due to the amount of time chemistry takes up on the timeline, the science is split into four general chronological categories. The four categories are: prehistoric times - beginning of the Christian era (black magic), beginning of the Christian era - end of 17th century (alchemy), end of 17th century - mid 19th century (traditional chemistry) and mid 19th century - present (modern chemistry).

Beginning of the Christian Era (Black Magic) [] || 1700 BC || King [|Hammurabi]'s reign over Babylon || Known metals were recorded and listed in conjunction with heavenly bodies. || End of 17th Century ([|Alchemy]) [] || 300 BC -300 AD || The Advent of the Alchemists || Influenced greatly by Aristotle's ideas, alchemists attempted to transmute cheap metals to gold. The substance used for this conversion was called the [|//Philosopher's Stone//]. || End of 17th Century - Mid 19th Century (Traditional Chemistry)
 * **Time Intervals** || **Specific Times** || **Events** || **Description** ||
 * Prehistoric Times -
 * ^  || 430 BC || [|Democritus] of ancient Greece || Democritus proclaims the atom to be the simplest unit of matter. All matter was composed of atoms. ||
 * ^  || 300 BC || Aristotle of ancient Greece || [|Aristotle] declares the existence of only four elements: fire, air, water and earth. All matter is made up of these four elements and matter had four properties: hot, cold, dry and wet. ||
 * Beginning of the Christian Era -
 * ^  || 13th Century (1200's) - 15th Century (1400's) || Failure of the [|Gold] Business || Although [|Pope John XXII] issued an edict against gold-making, the gold business continued. Despite the alchemists' efforts, transmutation of cheap metals to gold never happened within this time period. ||
 * ^  || 1520 || [|Elixir of Life] || Alchemists not only wanted to convert metals to gold, but they also wanted to find a chemical concoction that would enable people to live longer and cure all ailments. This elixir of life never happened either. ||
 * ^  || End of 17th Century || Death of Alchemy || The disproving of Aristotle's four-elements theory and the publishing of the book, The Skeptical Chemist //(by [|Robert Boyle]), combined to destroy this early form of chemistry.// ||

[] || 1700's || Phlogiston Theory Coulomb's Law || Johann J. Beecher believed in a substance called [|phlogiston]. When a substance is burned, phlogiston was supposedly added from the air to the flame of the burning object. In some substances, a product is produced. For example, calx of mercury plus phlogiston gives the product of mercury. [|Charles Coulomb] discovered that given two particles separated by a certain distance, the force of attraction or repulsion is directly proportional to the product of the two charges and is inversely proportional to the distance between the two charges. || Present ([|Modern Chemistry] or //20th Century Chemistry)
 * ^  || 1774-1794 || Disproving of the Phlogiston Theory || [|Joseph Priestley] heated calx of mercury, collected the colorless gas and burned different substances in this colorless gas. Priestley called the gas "dephlogisticated air", but it was actually oxygen. It was [|Antoine Lavoisier] who disproved the Phlogiston Theory. He renamed the "dephlogisticated air" oxygen when he realized that the oxygen was the part of air that combines with substances as they burn. Because of Lavoisier's work, Lavoisier is now called the "Father of Modern Chemistry". ||
 * ^  || 1803 || Dalton's Atomic Theory || [|John Dalton] publishes his Atomic Theory which states that all matter is composed of atoms, which are small and indivisible. ||
 * Mid 19th Century -

[]// || 1854 || Vacuum Tube || [|Heinrich Geissler] creates the first vacuum tube. || Radioactive Elements || [|J.J. Thomson] placed the Crookes' tube within a magnetic field. He found that the cathode rays were negatively charged and that each charge had a mass ratio of 1.759E8 coulombs per gram. He concluded that all atoms have this negative charge (through more experiments) and he renamed the cathode rays electrons. His model of the atom showed a sphere of positively charged material with negative electrons stuck in it. Thomson received the 1906 [|Nobel Prize] in physics. [|Marie Curie] discovered uranium and thorium within pitchblend. She then continued to discover two previously unknown elements: radium and polonium. These two new elements were also found in pitchblend. She received two nobel prizes for her discovery; one was in chemistry while the other was in physics. || Neutron Bombardment and Nuclear Fission || [|James Chadwick] discovers the neutron. [|Enrico Fermi] bombards elements with neutrons and produces elements of the next highest atomic number. [|Nuclear fission] occurred when Fermi bombarded uranium with neutrons. He received the 1938 Nobel Prize in physics. ||
 * ^  || 1879 || [|Cathode Rays] || [|William Crookes] made headway in modern atomic theory when he used the vacuum tube made by Heinrich Geissler to discover cathode rays. Crookes created a glass vacuum tube which had a zinc sulfide coating on the inside of one end, a metal cathode imbedded in the other end and a metal anode in the shape of a cross in the middle of the tube. When electricity was run through the apparatus, an image of the cross appeared and the [|zinc sulfide] glowed. Crookes hypothesized that there must have been rays coming from the cathode which caused the zinc sulfide to fluoresce and the cross to create a shadow and these rays were called cathode rays. ||
 * ^  || 1885 || [|The Proton] || Eugene Goldstein discovered positive particles by using a tube filled with hydrogen gas (this tube was similar to Thomson's tube...see 1897). The positive particle had a charge equal and opposite to the electron. It also had a mass of 1.66E-24 grams or one atomic mass unit. The positive particle was named the proton. ||
 * ^  || 1895 || X-rays || [|Wilhelm Roentgen] accidentally discovered x-rays while researching the glow produced by cathode rays. Roentgen performed his research on cathode rays within a dark room and during his research, he noticed that a bottle of barium platinocyanide was glowing on a shelf. He discovered that the rays that were causing the fluorescence could also pass through glass, cardboard and walls. The rays were called [|x-rays]. ||
 * ^  || 1896 || Pitchblend || [|Henri Becquerel] was studying the fluorescence of pitchblend when he discovered a property of the pitchblend compound. [|Pitchblend] gave a fluorescent light with or without the aid of sunlight. ||
 * ^  || 1897 || [|The Electron and Its Properties]
 * ^  || 1909 || Mass of the Electron || [|Robert Millikan] discovered the mass of an electron by introducing charged oil droplets into an electrically charged field. The charge of the electron was found to be 1.602E-19 coulombs. Using Thomson's mass ration, Millikan found the mass of one electron to be 9.11E-28 grams. Millikan received the 1932 Nobel Prize in Physics for this discovery. ||
 * ^  || 1911 || Three Types of Radioactivity || [|Ernest Rutherford] sent a radioactive source through a magnetic field. Some of the radioactivity was deflected to the positive plate; some of it was deflected to the negative plate; and the rest went through the magnetic field without deflection. Thus, there were three types of radioactivity: [|alpha particles] (+), [|beta particles] (-) and [|gamma rays] (neutral). By performing other experiments and using this information, Rutherford created an atomic model different from Thomson's. Rutherford believed that the atom was mostly empty space. It contains an extremely tiny, dense positively charged nucleus (full of protons) and the nucleus is surrounded by electrons traveling at extremely high speeds. The Thomson model was thrown out after the introduction of the Rutherford model. ||
 * ^  || 1914 || Protons within a Nucleus || [|Henry Moseley] attempts to use x-rays to determine the number of protons in the nucleus of each atom. He was unsuccessful because the neutron had not been discovered yet. ||
 * ^  || 1932 || The Neutron
 * ^  || 1934 || Artificial Radioactive Elements || [|Irene Curie and Frederic Joliot-Curie] discovered that radioactive elements could be created artificially in the lab with the bombardment of alpha particles on certain elements. They were given the 1935 Nobel Prize. ||
 * ^  || 1940's || [|Manhattan Project] || [|Albert Einstein] and Enrico Fermi both warned the United States about Germany's extensive research on atomic fission reaction. Below the football field at the [|University of Chicago], the United States developed the very first working nuclear fission reactor. The Manhattan Project was in process. ||

= = Each link for each time interval contains some information about that period. Unfortunately, the information is sparse and the presentation of the info leaves much to be desired. However, more information on chemical history can be found in the links listed below. The list is collated in a chronological manner so like the table above, alchemy and black magic should be on top while traditional and modern chemistry should be closer to the end of the list. Also, there are some other links besides the ones that are in the time-interval section and these links should lead you to more information about the underlined topics.

=The History of Chemistry=

The earliest record of man's interest in chemistry was approximately 3,000 B.C, in the fertile crescent. At that time, chemistry was more an art than a science. Tablets record the first known chemists as women who manufactured perfumes from various substances. Ancient Egyptians produced certain compounds such as those used in mummification. By 1000 B.C, chemical arts included the smelting of metals and the making of drugs, dyes, iron, and bronze. Iron making was also introduced and refinement of lead and mercury was performed. The physical properties of some metals such as copper, zinc, silver, and gold were understood. Many groups of people contributed to these developments--among them were ancient Egyptians, Greeks, Hebrews, Chinese, and Indians.

taking for []

**History of Chemistry**
The earliest practical knowledge of chemistry was concerned with [|metallurgy], pottery, and dyes; these crafts were developed with considerable skill, but with no understanding of the principles involved, as early as 3500 B.C. in Egypt and Mesopotamia. The basic ideas of element and compound were first formulated by the Greek philosophers during the period from 500 to 300 B.C. Opinion varied, but it was generally believed that four elements (fire, air, water, and earth) combined to form all things. Aristotle's definition of a simple body as “one into which other bodies can be decomposed and which itself is not capable of being divided” is close to the modern definition of element. About the beginning of the Christian era in Alexandria, the ancient Egyptian industrial arts and Greek philosophical speculations were fused into a new science. The beginnings of chemistry, or [|alchemy], as it was first known, are mingled with occultism and magic. Interests of the period were the transmutation of base metals into gold, the imitation of precious gems, and the search for the elixir of life, thought to grant immortality. Muslim conquests in the 7th cent. A.D. diffused the remains of Hellenistic civilization to the Arab world. The first chemical treatises to become well known in Europe were Latin translations of Arabic works, made in Spain c. A.D. 1100; hence it is often erroneously supposed that chemistry originated among the Arabs. Alchemy developed extensively during the Middle Ages, cultivated largely by itinerant scholars who wandered over Europe looking for patrons.

taken from columbia.org

[|www.100pies.net]

[|www.100pies.net]

[|www.100pies.net]

[|www.100pies.net]

March 1, 2010 History of the chimistry ​ On March 1, 1896, Antoine Henri Becqurel discovered radioactivity. Earlier in the week he planned an experiment to expose sunlight to uranium and then store the uranium in a black bag with a photographic plate. Earlier trials of the experiment resulted in an image of the uranium crystals on the photograph. He believed uranium absorbed sunlight and released the energy slowly by fluorescence. He planned to repeat his experiment on February 26, but it was cloudy with little sunlight. Becqurel decided to postpone his test and placed his uranium and photographic plate in a black bag and stored it in his desk.

When the weather cleared, he collected his materials to perform his experiment and discovered his photographic plate contained a clear image of the uranium crystals. The uranium did not need an external source to produce the image, but something inside the uranium gave off energy.

This discovery marks the beginning of the nuclear age and would earn Becqurel the 1903 Nobel Prize in Physics. Find out what else occurred on [|this day in science history].

**The Kinds of Matter**

Chemistry is defined as the study of matter. In this introductory text we will not study all types of matter. Rather, we will concentrate on simple substances, the properties that identify them, and the changes they undergo.

A pure substance consists of a single kind of matter. It always has the same composition and the same set of properties. For example, baking soda is a single kind of matter, known chemically as sodium hydrogen carbonate. A sample of pure baking soda, regardless of its source or size, will be a white solid containing 57.1% sodium, 1.2% hydrogen, 14.3% carbon, and 27.4% oxygen. The sample will dissolve in water. When heated to 270°C the sample will decompose, giving off carbon dioxide and water vapor and leaving a residue of sodium carbonate. Thus, by definition, baking soda is a pure substance because it has a constant composition and a unique set of properties, some of which we have listed. The properties we have described hold true for any sample of baking soda. These properties are the kinds in which we are interested.
 * Pure Substances ** [[image:../../cTutorial.GIF width="143" height="29" align="textTop" link="http://alcascience6a.wikispaces.com/Compounds/Compound.htm"]]
 * [[image:NaHCO3.gif width="200" height="98" align="center"]] ||
 * Baking Soda ||

A note about the term pure//; in this text, the word// pure //means a single substance, not a mixture of substances. As used by the U.S. Food and Drug Administration (USFDA), the term// pure //means "fit for human consumption." Milk, whether whole, 2% fat, or skim, may be// pure //(fit for human consumption) by public health standards, but it is not// pure// in the chemical sense. Milk is a mixture of a great many substances, including water, butterfat, proteins, and sugars. Each of these substances is present in different amounts in each of the different kinds of milk (Figure 1.1).

A mixture consists of two or more pure substances. Most of the matter we see around us is composed of mixtures. Seawater contains dissolved salts; river water contains suspended mud; hard water contains salts of calcium, magnesium, and iron. Both seawater and river water also contain dissolved oxygen, without which fish and other aquatic life could not survive.
 * ** FIGURE 1.1 ** Pure substances versus mixtures. The labels on a carton of milk and a box of baking soda show that milk is a mixture and baking soda is a pure substance. ||
 * Mixtures [[image:../../cTutorial.GIF width="143" height="29" align="textTop" link="http://alcascience6a.wikispaces.com/Mixtures/mixture.htm"]]**

Unlike the constant composition of a simple substance, the composition of a mixture can be changed. The properties of the mixture depend on the percentage of each pure substance in it. Steel is an example of a mixture. All steel starts with the pure substance iron. Refiners then add varying percentages of carbon, nickel, chromium, vanadium, or other substances to obtain steels of a desired hardness, tensile strength, corrosion resistance, and so on. The properties of a particular type of steel depend not only on which substances are mixed with the iron but also on the relative percentage of each. One type of chromium-nickel steel contains 0.6% chromium and 1.25% nickel. Its surface is easily hardened, a property that makes it valuable in the manufacture of automobile gears, pistons, and transmissions. The stainless steel used in the manufacture of surgical instruments, food-processing equipment, and kitchenware is also a mixture of iron, chromium, and nickel; it contains 18% chromium and 8% nickel. Steel with this composition can be polished to a very smooth surface and is very resistant to rusting.

You can often tell from the appearance of a sample whether it is a mixture. For example, if river water is clouded with mud or silt particles, you know it is a mixture. If a layer of brown haze lies over a city, you know the atmosphere is mixed with pollutants. However, the appearance of a sample is not always sufficient evidence by which to judge its composition. A sample of matter may look pure without being so. For instance, air looks like a pure substance but it is actually a mixture of oxygen, nitrogen, and other gases. Rubbing alcohol is a clear, colorless liquid that looks pure but is actually a mixture of isopropyl alcohol and water, both of which are clear, colorless liquids. As another example, you cannot look at a piece of metal and know whether it is pure iron or a mixture of iron with some other substance such as chromium or nickel. Figure 1.2 shows the relationships between different kinds of matter.



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 * ** FIGURE 1.2 ** Classification of matter. ||

Evolution of Modern Chemistry
In the hands of the “Oxford Chemists” (Robert Boyle, Robert Hooke, and John Mayow) chemistry began to emerge as distinct from the pseudoscience of alchemy. Boyle (1627–91) is often called the founder of modern chemistry (an honor sometimes also given Antoine Lavoisier, 1743–94). He performed experiments under reduced pressure, using an air pump, and discovered that volume and pressure are inversely related in gases (see [|gas laws]). Hooke gave the first rational explanation of [|combustion]—as combination with air—while Mayow studied animal respiration. Even as the English chemists were moving toward the correct theory of combustion, two Germans, J. J. Becher and G. E. Stahl, introduced the false phlogiston theory of combustion, which held that the substance phlogiston is contained in all combustible bodies and escapes when the bodies burn. The discovery of various gases and the analysis of air as a mixture of gases occurred during the phlogiston period. Carbon dioxide, first described by J. B. van Helmont and rediscovered by Joseph Black in 1754, was originally called fixed air. Hydrogen, discovered by Boyle and carefully studied by Henry Cavendish, was called inflammable air and was sometimes identified with phlogiston itself. Cavendish also showed that the explosion of hydrogen and oxygen produces water. C. W. Scheele found that air is composed of two fluids, only one of which supports combustion. He was the first to obtain pure oxygen (1771–73), although he did not recognize it as an element. Joseph Priestley independently discovered oxygen by heating the red oxide of mercury with a burning glass; he was the last great defender of the phlogiston theory. The work of Priestley, Black, and Cavendish was radically reinterpreted by Lavoisier, who did for chemistry what Newton had done for physics a century before. He made no important new discoveries of his own; rather, he was a theoretician. He recognized the true nature of combustion, introduced a new chemical nomenclature, and wrote the first modern chemistry textbook. He erroneously believed that all acids contain oxygen.

Impact of the Atomic Theory
The assumption that compounds were of definite composition was implicit in 18th-century chemistry. J. L. Proust formally stated the law of constant proportions in 1797. C. L. Berthollet opposed this law, holding that composition depended on the method of preparation. The issue was resolved in favor of Proust by John Dalton's atomic theory (1808). The atomic theory goes back to the Greeks, but it did not prove fruitful in chemistry until Dalton ascribed relative weights to the atoms of chemical elements. Electrochemical theories of chemical combinations were developed by Humphry Davy and J. J. Berzelius. Davy discovered the alkali metals by passing an electric current through their molten oxides. Michael Faraday discovered that a definite quantity of charge must flow in order to deposit a given weight of material in solution. Amedeo Avogadro introduced the hypothesis that equal volumes of gases at the same pressure and temperature contain the same number of molecules. William Prout suggested that as all elements seemed to have atomic weights that were multiples of the atomic weight of hydrogen, they could all be in some way different combinations of hydrogen atoms. This contributed to the concept of the [|periodic table] of the elements, the culmination of a long effort to find regular, systematic properties among the elements. [|Periodic laws] were put forward almost simultaneously and independently by J. L. Meyer in Germany and D. I. Mendeleev in Russia (1869). An early triumph of the new theory was the discovery of new elements that fit the empty spaces in the table. William Ramsay's discovery, in collaboration with Lord Rayleigh, of argon and other inert gases in the atmosphere extended the periodic table

Organic Chemistry and the Modern Era
Organic chemistry developed extensively in the 19th cent., prompted in part by Friedrich Wohler's synthesis of urea (1828), which disproved the belief that only living organisms could produce organic molecules. Other important organic chemists include Justus von Liebig, C. A. Wurtz, and J. B. Dumas. In 1852 Edward Frankland introduced the idea of valency (see [|valence]), and in 1858 F. A. Kekule showed that carbon atoms are tetravalent and are linked together in chains. Kekule's ring structure for benzene opened the way to modern theories of organic chemistry. Henri Louis Le Châtelier, J. H. van't Hoff, and Wilhelm Ostwald pioneered the application of thermodynamics to chemistry. Further contributions were the phase rule of J. W. Gibbs, the ionization equilibrium theory of S. A. Arrhenius, and the heat theorem of Walther Nernst. Ernst Fischer's work on the amino acids marks the beginning of molecular biology. At the end of the 19th cent., the discovery of the [|electron] by J. J. Thomson and of [|radioactivity] by A. E. Becquerel revealed the close connection between chemistry and [|physics]. The work of Ernest Rutherford, H. G. J. Moseley, and Niels Bohr on atomic structure (see [|atom]) was applied to molecular structures. G. N. Lewis, Irving Langmuir, and Linus Pauling developed the electronic theory of [|chemical bonds], directed valency, and molecular orbitals (see [|molecular orbital theory]). Transmutation of the elements, first achieved by Rutherford, has led to the creation of elements not found in nature; in work pioneered by Glenn [|Seaborg] elements heavier than uranium have been produced. With the rapid development of [|polymer] chemistry after World War II a host of new synthetic fibers and materials have been added to the market. A fuller understanding of the relation between the structure of molecules and their properties has allowed chemists to tailor predictively new materials to meet specific needs. taken from www.infoplease.com taken from csc.edu =Chemistry Experiments= This is a collection of chemistry experiments and research projects. Most of the experiments involve general chemical principles. Sites offering general and physical science are included, too, providing the website offers chemistry experiments. taken from:http://chemistry.about.com/od/workedchemistryproblems/a/scalar-product-vectors-problem.htm

[|bubble Life Versus Temperature Experiment]
brokenchopstick, FlickrThe purpose of this experiment is to determine if temperature affects how long bubbles last before they pop. In order to do this experiment you need bubble solution or dishwashing detergent, jars, and either a thermometer or some way to gauge the temperature of different locations. You can conduct other experiments by comparing different brands of bubble solution or other liquids or by examining the effect of humidity on bubble life. taken from:http://chemistry.about.com/od/chemistryexperiments/tp/scienceexperiments.htm