Independent Variable: Concentration. History of Chemistry Chemistry has been around for a various amount of years. The beginning of chemistry was first acknowledged in 10, BC. The ancient civilizations used technologies that came to become the makeup of the many branches of chemistry. These early civilizations would extract metal from ores, make pottery and glazes, beer and wine fermentation, extraction of chemicals from plants for medicine, making fat into soap, making glass, and many chemistry related tasks were done.
Forensic Chemistry Forensic Chemistry is a branch of chemistry that deals with chemical analysis of evidence found at crime sites and any other substance that may have been used during a crime. Examples would be like analyzing the weapon for DNA and fingerprints, and analyzing any substance like spit or blood that might contain the criminal's or the victim's DNA in it. Forensic Chemistry is very popular today, as it is in many famous TV shows, especially CSI, which means crime scene investigator.
Chirality in Chemistry Chirality is a term which may be applied to any asymmetric object or molecule. It is the property of non-identity of an object with its mirror image. A chiral compound is one which is not superimposable on its mirror image. This property of molecules has a great importance in the chemistry feild as it provides us with an understanding of the shapes of molecules which then in turn, gives us an insight on the way they react in a particular reaction.
The History of Chemistry Chemistry is the science of the composition and structure of materials and of the changes that materials undergo. It is also used in improving standards of living, making it possible for such substances as rubber, nylon, and plastics to be made from completely different materials. New materials and new properties of old materials are always being discovered. Some earlier products discovered from chemical reactions are ceramics, glass, and metals.
Dyes and medicines. Chemistry is the study of the composition, structure, and properties of matter and the changes that matter undergoes Modern Chemistry, Holt McDougal pg. Chemistry and technology are together and separate. Chemistry uses technology and technology uses chemistry. The history of chemistry and technology is long going back to the ancient times. Chemistry was used even by the oldest civilizations, like Egypt.
It was really popular during the medieval times. As the years went by, Alchemy became a lost art and chemistry took it in place. Chemistry led. Chemistry has been around for a very long time. Chemistry is the branch of physical science that studies composition, properties, energy, and behavior of matter. It is said that chemistry has been around since prehistoric times. This was in the form of everyday objects like pottery, cosmetics and perfumes, and extracting metals from ores.
Chemistry is based on the discovery and study of elements. Some elements were known to ancient man, but most were discovered by chemists and alchemists. Some say. Chemistry has been around since the dawn of time, way before humans realized what chemistry was or its importance. The building blocks of the earth, such as minerals of the soil and atmospheric gases, all arise from chemical elements. Natural resources are all chemicals or chemical compounds, and the study.
It covers all chemical compounds except organic compounds. Inorganic chemists study things such as crystal. Section Assessment Page 11 5. A chemist would do examples A and C. If you have a good knowledge of chemistry, it allows you to be able to evaluate data presented, make an informed opinion and act on that opinion.
Page 17 8. Chemists meet the demands of energy by finding ways to conserve, produce and store energy. They help doctors develop medicines and other technology to allow doctors to successfully treat their patients. Chemists role in agriculture is to develop more. Green Chemistry is the making of chemical products that reduces or eliminates the use and production of hazardous substances in the designing, making, and use of chemical products. It involves the designing and re-designing of chemical creation and chemical products to prevent pollution which will therefore solve environmental problems.
Green Chemistry is environmentally safe and has very little side effects on. The earliest knowledge of chemistry was in B. C in Egypt and Mesopotamia. Chemistry was concerned anything that was pottery, dyes or crafts that were developed but not considerable skills because no one truly understood its purpose. The basic idea of elements or compounds were first formulated by Greek philosopher during to B. C when people believed fire , water, earth, and air combined to form all living and non-living things.
In the beginning of Christianity an ancient Egyptian and Greek. Green Chemistry is the use of chemistry for the prevention of chemical pollution to the environment by using chemicals that are benign, or not harmful. In order to gain strong insight into the surface chemistry of silica we have perform a thorough literature search. Our goal is to identify the pioneer research performed on silica and silica supported catalyst. Particular interest lies in silica-water-cobalt and silica-alcohol-cobalt systems. This study is both on macro and micro level so that a complete theoretical base can be established.
From this theoretical knowledge, key areas to look upon will be identified and a design of experiments will. What chemistry means to me and how it impacts upon my life From the foods we eat and the medicines we take to the products we regularly use, our lives are inextricably linked to chemicals and their operating principles.
Chemistry is everywhere. The air we breathe, the ground we stand on, the seas we sail, and the variety of living things including our own bodies; all these are made of substances that we call chemicals. These chemicals interact with one another, and, in many cases, these interactions. The history of chemistry makes a span of time reaching from ancient history to the present. By BC, ancient civilizations used technologies that would eventually form the basis of the various branches of the subject. Examples include extracting metals from ores, making pottery and glazes, fermenting beer and wine, extracting chemicals from plants for medicine and perfume, rendering fat into soap, making glass, and making alloys like bronze.
The science of chemistry, alchemy, was unsuccessful. Laboratory course is an integral part of chemistry education and accounts for a major percentage of the assessment marks. Chemistry laboratory is a place where the fundamental rules of laboratory techniques which are very important for students at all levels can be learnt.
Observations are foreword of experimentation but preconditioned by outline of practical understanding. Design and choice of experimental method may influence the result. Willamette Promise. College Credit in High School. This content can also be downloaded as Interactive PDF. For the interactive PDF, adobe reader is required for full functionality.
This text is published under creative commons licensing, for referencing and adaptation, please click here. Croix river in the western edge of the state. A line of people are seated at tables set up inside a canvas tent. In front of a cheering crowd of friends, family, and neighbors, these brave souls are about to do battle. Unfortunately for the contestants, the fruit in question is the habanero, one of the hotter varieties of chili pepper commonly found in markets in North America.
In this particular event, teams of five people will race to be the first to eat a full pound of peppers. As the eating begins, all seems well at first. Within thirty seconds, though, what begins to happen is completely predictable and understandable to anyone who has ever mistakenly poured a little too much hot sauce on the dinner plate. Faces turn red, sweat and tears begin to flow, and a copious amount of cold water is gulped down.
Composed of the four elements carbon, hydrogen, oxygen and nitrogen, capsaicin is produced by the pepper plant for the purpose of warding off hungry mammals. Interestingly, birds also have a heat receptor protein which is very similar to the TrpV1 receptor in mammals, but birds are not at all sensitive to capsaicin. The region of the receptor which is responsible for capsaicin sensitivity appears to be quite specific. In , scientists were able to insert a small segment of the capsaicin-sensitive rat TrpV1 receptor gene into the non-sensitive chicken version of the gene, and the resulting chimeric mixed species receptor was sensitive to capsaicin Cell , , Back at the North Hudson Pepperfest, those with a little more common sense are foregoing the painful effects of capsaicin overload and are instead indulging in more pleasant chemical phenomena.
A little girl enjoying an ice cream cone is responding in part to the chemical action of another organic compound called vanillin. What is it about capsaicin and vanillin that causes these two compounds to have such dramatically different effects on our sensory perceptions?
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Both are produced by plants, and both are composed of the elements carbon, hydrogen, oxygen, and in the case of capsaicin nitrogen. Since the birth of chemistry as a science, chemists have been fascinated — and for much of that history, mystified — by the myriad properties of compounds that come from living things.
They also began to more fully appreciate the unique features of the element carbon which makes it so central to the chemistry of living things, to the extent that it warrants its own subfield of chemistry. Carbon forms four stable bonds, either to other carbon atoms or to hydrogen, oxygen, nitrogen, sulfur, phosphorus, or a halogen. The characteristic bonding modes of carbon allow it to serve as a skeleton, or framework, for building large, complex molecules that incorporate chains, branches and ring structures.
Although humans have been eating hot peppers and vanilla-flavored foods for centuries, we are just now, in the past few decades, beginning to understand how and why one causes searing pain and the other pure gustatory pleasure. We understand that the precise geometric arrangement of the four elements in capsaicin allows it to fit inside the binding pocket of the TrpVI heat receptor, but as of today, we do not yet have a detailed three dimensional picture of the TrpVI protein bound to capsaicin. We also know that the different arrangement of carbon, hydrogen and oxygen atoms in vanillin allows it to bind to specific olfactory receptors, but again, there is much yet to be discovered about exactly how this happens.
In this chapter, you will be introduced to some of the most fundamental principles of organic chemistry. With the concepts we learn about, we can begin to understand how carbon and a very small number of other elements in the periodic table can combine in predictable ways to produce a virtually limitless chemical repertoire.
As you read through, you will recognize that the chapter contains a lot of review of topics you have probably learned already in an introductory chemistry course, but there will likely also be a few concepts that are new to you, as well as some topics which are already familiar to you but covered at a greater depth and with more of an emphasis on biologically relevant organic compounds. We will review the common bonding patterns of the six elements necessary for all forms of life on earth — carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus — plus the halogens fluorine, chlorine, bromine, and iodine.
Back to the Top. More rarely, halogens such as chlorine, bromine and iodine can also be incorporated into organic molecules. Hydrogen is an exception to the octet rule as it is the smallest element and its valence shell is filled with two electrons. Thus, hydrogen can form one bond with another atom. Sulfur and phosphorus can also have bonding patterns that are exceptions to the octet rule. They both have expanded orbital bonding with phosphorus also routinely forming five covalent bonds, and sulfur being capable of forming either four or six covalent bonds.
Table 5. When you are drawing organic molecules, it is important to pay attention to the bonding rules so that all atoms reach their preferred bonding states. When electrons in a molecule can shift from one area of the molecule to another to create these alternative structures. Note that resonance structures give chemists a more concrete way of thinking about molecules. Instead, they exist in a more amorphous transitional state that is somewhere in between all of the possible combinations. This can be done using the formal charge method of drawing Lewis structures.
This is not the preferred configuration for oxygen, but because oxygen is so electronegative, it can carry a negative formal charge more easily than atoms with less electronegativity. This is the most common form of phosphorus found in all living organisms on the planet, including humans. Figure 5. ATP structure and the B.
DNA structure. This will be the central atom s that the other, more electronegative atoms, are bonded around. Note that hydrogen can never be a central atom as it can only make one covalent bond.
Also, list any extra electrons due to the negative charge on the overall molecule and your expectations about the bonding capacity of each atom to reach the octet. Note that we have four oxygen atoms that have to bond to the phosphorus. To do this add up all the valence electrons for each atom present. If you run out of electrons before all the atoms have filled valence shells begin making double bonds where necessary. Calculate the formal charge on each atom in the molecule and then use the sum to calculate the formal charge on the whole molecule.
Watch the video tutorial above to help you draw out the Lewis structure of phosphate. You will see that you need to start with the center phosphorus. For phosphorus, we know that it will make 5 bonds in the expanded orbital format Table 5. So start by drawing in those 5 bonds. After this fill in the lone pair electrons for all of the atoms, until you reach a total of 32 electrons. Next, calculate the formal charges on each atom.
Since three of the oxygens have a 1 — charge and the other two atoms are zero, the overall charge on the molecule is 3 —. The completed Lewis structure for phosphate should look like this:. Thus, each oxygen surrounding the phosphorus should have equal opportunity to form the double bonded position. We have shown the double bond forming in the downward position, but it has an equally probable chance of forming with any of the other three oxygens. Thus, we can show the structure with the double bond position in all of the other possible conformations:.
In actuality, none of the resonance structures represent the true structure. The true structure is somewhere in between all of the possible resonance conformations. Organic molecules, compared to the simple salts and covalent compounds shown in Chapters 3 and 4, can be quite large and sprawling structures with many branches.
Thus, it is important to understand how to draw organic molecules so that you can understand the 3-dimensional shape of the molecule. By convention, carbon is listed first, hydrogen second, followed by oxygen, nitrogen, sulfur, phosphorus, and finally any halogens. Thus, molecular formulae are very rarely used in organic chemistry, because they do not give useful information about the bonding in the molecule.
One of the few places where you might come across them is in equations for the combustion of simple hydrocarbons , for example:. However, for most biologically important reactions, the shape of the molecule is usually critical for the function of the molecule, very similar to a key fitting into a lock. Thus, the bonding order becomes very important. For example, C 5 H 12 shown in the equation above can be bonded together in more than one way:. However, each of these structures represents a different molecule with slightly different chemical properties. When compounds share the same molecular formula, but have a different bonding order of the atoms, they are known as structural isomers.
A structural formula shows how the various atoms are bonded, and can be more useful that only writing the molecular formula for a compound. They include the displayed formula, condensed formulas, and line structures. A displayed formula shows all the bonds in the molecule as individual lines with each atom written at the end of each line using its elemental abbreviation from the periodic table.
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You need to remember that each line represents a pair of shared electrons. Thus, for organic chemistry, it is important to begin thinking about the structures in their 3-D form. The more you practice, the more you will be able to visualize and turn the molecule around in your head. For example, consider the simple molecule with the molecular formula CH 2 Cl 2. You might think that there were two different ways of arranging these atoms if you drew a displayed formula. But these two structures are actually exactly the same.
The molecule is not flat, in the plane of the paper. One structure is in reality a simple rotation of the other one.
Consider a slightly more complicated molecule, C 2 H 5 Cl. The displayed formula could be written as either of these:. But, again these are exactly the same. Look at the models below. Notice that the partially condensed structure still provides a very clear picture of where each of the atoms is bonded in space. The three hydrogens are also complete with their single bonds to the first carbon. We need to assign the remaining three bonds.
From the condensed formula, it is clear that the first oxygen is attached to the second carbon, however, after that, we become unsure about the position of the second oxygen.
When you are unsure of which atom is bonded to which, it is best to draw out the potential structures and evaluate them for their potential correctness. From the analysis of the potential structures above, it is clear that neither structure satisfies the octet rule for one or more atoms within the molecule as currently written. In the upper diagram, both the second carbon and the first oxygen atom are lacking one bond.
This structure can easily satisfy the octet rule by placing a double bond between carbon 2 and oxygen 1 within the molecule. Whereas, a solution for the missing two carbon bonds for the second carbon in the lower structure is not easily remedied. Thus, the upper structure is a more probable structure than the lower structure with the addition of the double bond between the carbon and the oxygen.
While condensed structures are easier to write than displayed or partially condensed structures they can prove to be a little more challenging to determine the three dimensional bonding pattern of the atoms. Thus, chemistry is the study of matter, biology is the study of living things, and geology is the study of rocks and the earth.
Mathematics is the language of science, and we will use it to communicate some of the ideas of chemistry. Although we divide science into different fields, there is much overlap among them. For example, some biologists and chemists work in both fields so much that their work is called biochemistry. Similarly, geology and chemistry overlap in the field called geochemistry. There are many other fields of science, in addition to the ones biology, medicine, etc.
As our understanding of the universe has changed over time, so has the practice of science. Chemistry in its modern form, based on principles that we consider valid today, was developed in the s and s. Before that, the study of matter was known as alchemy and was practiced mainly in China, Arabia, Egypt, and Europe. Alchemy was a somewhat mystical and secretive approach to learning how to manipulate matter.
Practitioners, called alchemists, thought that all matter was composed of different proportions of the four basic elements—fire, water, earth, and air—and believed that if you changed the relative proportions of these elements in a substance, you could change the substance. Alchemists used symbols to represent substances, some of which are shown in the accompanying figure. This was not done to better communicate ideas, as chemists do today, but to maintain the secrecy of alchemical knowledge, keeping others from sharing in it.
The first affinity table. Table of different relations observed in chemistry between different substances; Memoirs of the Royal Academy of Sciences, p. Alchemists used symbols like these to represent substances. In spite of this secrecy, in its time alchemy was respected as a serious, scholarly endeavor. Isaac Newton, the great mathematician and physicist, was also an alchemist. The study of modern chemistry has many branches, but can generally be broken down into five main disciplines, or areas of study:. In practice, chemical research is often not limited to just one of the five major disciplines.