The first difficulty a student encounters is the amount of study material available about organic molecules and their reactions any standard text book is not less then 1400 pages long, a student cannot expect to learn all this material without investing a considerable time and effort in studying it and if he does so he disproportionate his time allocations with other subjects eventually bringing him under pressure to leave organic chemistry or compromise at other subjects.

The solution of above problem is that someone should work on your part to extract all relevant important matter and concept for you, this someone is your teacher. Most of standard text book (like I L Finar Morison boyd) available in market are not oriented for JEE preparation, rather these are among the best books available for college students all over the world. The sequence of chapters or 100% content may not return you for the time you have invested. You need not follow line to line of the text but choose the desired component from the word index given at the back of book.

In many ways, learning organic is like learning another language. Make sure you are familiar with basic terms like electrophile, nucleophile, base, substrate, carbocations, free radical electron releasing groups etc.

You should understand the nature of organic chemistry when a reaction occurs one must first know what reagents are the starting materials and what the final products are? The conversion of starting materials to the products will involve either breaking bonds, making bonds or both. The detailed sequence of which bonds are broken and formed, in what order, and the stereochemical relationships of these bonds is called a mechanism for the reaction.

Your text book is organized primarily by types of compounds which contain a specified functional group, eg. collection of all compounds where – OH group is connected to a carbon chain or structure are called alcohols.

When you study each type of functional group you will find that each reacts by only a few mechanistic paths and hence has a chemical personality of its own. Do not treat mechanism as just another thing to memorize, remember working organic chemist do not just repeat what is known. They use that knowledge to solve problems and discover new chemistry.

Understanding mechanism is the key to modern organic chemistry although we will be studying hundreds or thousands of reactions, these reactions occur via only a few fundamental mechanistic path ways. It is the recognition of the mechanistic similarities between different reactions that allow organic chemistry to be readily understood. Understanding mechanism will help make sense of thousand of facts that comprise organic chemistry.

IIT-JEE question appears as if it is newly framed for you but you will find at least some what related what you have done in mastering the mechanism the only challenge these questions pose is that you have to identify an appropriate mechanism component which operates there.

Anticipate what will be on the exam. Notice what the teacher spends time on in class. If you teacher assigns a specific problems make sure you know how to work every one of these problems. Your teacher know important concepts, mechanism or part of subject from which a question of JEE level can be framed, so they will even say “This problem will be on exam”. If your teacher says this, believe it !.

When you analyze your minor tests you should understand what you did wrong. You will need to know had to do it right next time because chemistry builds up from the base of knowledge, everything you learn at the beginning will be needed later for something more complicated. If you miss a concept on the first test it will be trouble for all coming minor tests.

Among chemists, organic chemists have always relied on inorganic reagents to carry out syntheses; this trend is increasing as organic synthesis turns more and more to the use of specific transition metal catalysts and nonmetallic compounds. Analytical chemists are often concerned with the detection and quantification of elements other than carbon, and often use chelating ligands of appropriate hardness or softness to concentrate and detect metallic elements. Physical and theoretical chemists are concerned with measuring or calculating the fundamental properties of inorganic and organic substances. Modern biochemists are becoming increasingly aware of the critical role played in living systems by metal ions. In addition there are many times when any chemist must make up a solution of a new type of inorganic reagent, modify a synthesis, detect an element in a new form, or study the properties of a different type of inorganic compound. At this point, the chemist needs to have some ability to anticipate the properties of inorganic compounds he or she has not dealt with in the past.

Academic chemists are not the only ones who deal in a non routine way with the compounds of elements other than carbon. Most of the largest volume industrial chemicals are inorganic compounds.

Many scientists and engineers who do not even consider themselves to be chemists must also deal with inorganic chemicals in a safe and insightful way. Biologists may have to make up a solution of an inorganic reagent, and may need to anticipate whether the material will explode on contact with water, or will fail to dissolve when they try to make up the solution! Environmental and aquatic chemistry, toxicology and medicinal chemistry, industrial chemistry, chemical safety, geochemistry, and materials science and solid state physics and chemistry all deal with a wide variety of inorganic compounds. Scientists in these fields need ways to anticipate the properties of new inorganic compounds. Chemists who develop a good fundamental understanding of the facts and principles of inorganic chemistry not only make better chemists, but they also may find opportunities to contribute to fields allied with traditional chemistry.

In recent years, the trend for inorganic chemists to interact with scientists from these other fields has paid some spectacular dividends. The mid-1980s discovery of superconductivity, a property that persists to unusually high temperatures in an unexpected class of materials known as the metal oxides resulted both in a Nobel prize for the discoverers and in a an increased study of inorganic materials. Since the discovery, the rate of these new vista-opening discoveries has grown to a point where each December the very eminent journal science began choosing a “molecule of the Year.”

Of the first four Molecules of the Year, three have been inorganic materials. The first was a biochemical material, DNA polymerase; but in 1990 the Molecule of the year was diamond, which, of course, was no new substance, but which was being produced by new methods and in new forms. The 1991 Molecule of the year was another form of the element carbon, the famous molecule C60, named “buckminsterfullerene” because its architecture and symmetry resembled those of the strong “geodesic domes” previously proposed by the environmental architect Buckminster Fuller; the chain of events leading to the discovery of this molecule began in outer space, where astronomers were seeking to explain certain unassigned spectroscopic frequencies that they thought were originating with interstellar carbon-containing molecules. The 1992 Molecule of the year was another old time inorganic molecule, one of the 10 simplest in the universe, nitric oxide. This molecule was  discovered by a medical researcher, Solomon Snyder, to be an important chemical messenger in the body, functioning as a neurotransmitter alongside of more familiar biochemical substances such as acetylcholine, and being involved intimately in the chemistry of the brain and of human sexual performance.

No one can predict what next year’s discovery of the year will be; only a few things seem reasonably predictable about these future revolutionary discoveries. More and more, they are interdisciplinary discoveries, in which inorganic chemistry plays a crucial role but by no means the only role.  These molecules may originate in the research laboratories of inorganic chemistry, in the environmental field, or in outer space; they may involve familiar old inorganic molecules that may have disappeared from inorganic texts that strive to emphasize only the current “hot” areas of research. Although no one can predict these discoveries, it does seem likely that they will be made, and more quickly exploited, by scientists who have a broad understanding of all aspects of inorganic chemistry, from the “pedestrain” realms of aqueous reaction chemistry, to modern sol-gel chemistry and to “hot” current areas such as materials science and catalysis, where this discovery might evolve from your professor’s own are of research.

One chemist may hope that by understanding certain materials, he or she will be able to find a cure for a disease or a solution for as environmental ill. Another chemist may simply want to understand a phenomenon. Because chemistry deals with  all materials, it is a subject of enormous breadth. It would be difficult to exaggerate the influence of chemistry on modern science and technology or on our ideas about our planet and the universe. In the section that follows, we will take a brief glimpse at modern chemistry and see some of the ways it has influenced technology, science, and modern thought.

Modern Chemistry: A brief Glimpse

For thousands of years, human being have fashioned natural materials into useful products. Modern chemistry certainly has its roots in the endeavor. After the discovery of fire, people begun to notice changes in certain rocks and minerals exposed to high temperatures. From these observations came the development of ceramics, glass, and metals, which today are among our most useful materials. Dyes and medicines were other early products obtained from natural substances. For example, the ancient.

Phoenicians extracted a bright purple dye, known as Tyrian purple, from a species of sea snail. One ounce of Tyrian purple required over 200,000 snails, because of its brilliant hue and scarcity, the dye became the choice of royalty.

Although chemistry has its roots in early technology, chemistry as a field of study based on scientific principles came into being only in the latter part of the eighteenth century. Chemists begun to look at the precise quantities of substances they used in their experiments. From this work came the central principle of substances they used in their experiments. from this work came the central principle of modern chemistry: the materials around us are composed of exceedingly small particles called atoms, and the precise arrangement of these atoms into molecules or more complicated structures accounts for the many different characteristics of materials. Once chemists understood this central principle, they could begin to fashion molecules to order. They could synthesize molecules; that is, they could build large molecules from small ones. Tyrian purple, for example, was eventually synthesized from the simpler molecule aniline.

The liquid-crystal displays (LCDs) that are used on everthing from watches and cell phones to computer monitors and televisions are an example of an application that depends on the special characteristics of materials. The liquid crystals used in these displays are a form of matter intermediate in characteristics between those of liquids and those solid crystals – hence the name. Many of these liquid crystals are composed of rodlike molecules that tend to align themselves something like the wood matches in a matchbox. The liquid crystals are held in alignment in layers by plates that have microscopic grooves. The molecules are attached to small electrodes or transistors. When the molecules are subjected to an electric charge from the transistor or electrode, they change alignment to point in a new direction, when they change direction, the change how light passes through their layer. When the liquid crystal layer is combined with a light source and color filters, incremental changes of alignment of the molecules throughout the display allow for images that have high contrast and millions of colors.

Chemists continue to develop new materials and discover new properties of old ones. Electronics and communications, for example, have been completely transformed by technological advances in materials. Optical-fiber cables have replaced long-distance telephone cables made of copper wire. Optical-fibers are fine threads of extremely pure glass. Because of their purity, these fibers can transmit laser light pulses for miles compared with only a few inches in ordinary glass. Not only is optical-fiber cable cheaper and less bulky than copper cable carrying the same information, but through the use of different colors of light, optical-fiber cable can carry voice, data, and video information at the same time. At the ends of an optical-fiber cable, devices using other new materials convert the light pulses to electrical signals and back, while computer chips constructed from still other materials process the signals.

Chemistry has also affected the way we think of the world around us, for example biochemists and molecular biologists -scientists who study the molecular basis of living organisms  – have made a remarkable finding: all forms of life appear to share many of the same molecules and molecular processes. Consider the information of inheritance, the genetic information that is passed on from one generation of organism to the next. Individual organisms, whether bacteria or human beings, store this information in a particular kind of molecule called deoxyribonucleic acid, or DNA.

DNA consists of two interwined molecular chains; each chain consists of links of four different types of molecular pieces, or bases, Just as you record information on a page by stringing together characters, an organism stores the information for reproducing itself in the order of these bases in its DNA. In a multicellular organism, such as a human being, every cell contains the same DNA.

Introduction

The following information should be entered before you begin the laboratory session:

Date
Enter the date at the top of the page. Use an ambiguous date format, such as 2 September 2008 or September 2, 2008 rather than 2/9/8 or 9/2/8. If the experiment runs more than one day, enter the starting date here and the new date in the procedure/data section at the time you actually begin work on that date.

Experiment title
If the experiment is from this or another laboratory manual, use the name from that manual and credit the manual appropriately. For example, “Quantitative Analysis of Chlorine Bleach by Redox Titration (illustrated Guide to Home Chemistry Experiments, #20.2)” If the experiment is your own, give it a description title.

Purpose
Write one or two sentences that describe the goal of the experiment. For example, “To determine the concentration of chlorine laundry bleach by redox titration using a starch-iodine indicator.”

Introduction (optional)
Any preliminary notes, comments, or other information may be entered in a paragraph or two here. For example, if you decided to do this experiment to learn more about something you discovered in another experiment, not that fact here.

Balanced equations
Write down balanced equations for all of the reactions involved in the experiment, including if applicable, changes in oxidation state.

Chemical information
Important information about all chemicals used in the experiment, including, if appropriate, physical properties (melting/boiling points, density, etc.), a list of relevant hazards and safety measures from the MSDS (the Material Safety Data Sheet for the chemical), and any special disposal methods required. Include approximate quantities, both in grams and in moles, to give an idea of the scale of the experiment.

Planned procedure
A paragraph or two to describe the procedures you expect to follow.

Main body

The following information should be entered as you actually do the experiment:

Procedure
Record the procedure you use, step by step, as you actually perform the procedures. Note any departures from your planned procedure and the reasons for them.

Data
Record all data and observations as you gather them, inline with your running procedural narrative. Pay attention to significant figures, and include information that speaks to accuracy and precision of the equipment and chemicals, you use. For example, if one step involves adding hydrochloric acid to a reaction vessel, it makes a difference if you added 5 mL of 0.1M hydrochloric acid from a 10 mL graduated cylinder or 5.00 mL or 0.1000M hydrochloric acid from a 10 mL pipette.

Sketches
If your setup is at all unusual, make a sketch of it here. It needn’t be fine art, nor does it need to illustrate common equipment or setups such as a beaker or a filtering setup. The goal is not to make an accurate representation of how the apparatus actually appears on your tab bench, but rather to make it clear how the various components relate to each other. Be sure to clearly label any relevant parts of the set up.

Calculations
Include any calculations you make. If you run the same calculation repeatedly on different data sets, one example calculation suffices.

Table(s)
If appropriate, construct a table or tables to organize your data. Copy data from your original inline record to the table or tables.

Graph(s)
If appropriate, construct a graph or graphs to present your data and show relationships between variables. Label the axes appropriately, include error bars if you know the error limits, and make sure that all of the data plotted in the graph are also available to the reader in tabular form. Hand-drawn graphs are preferable. If you use computer-generated graphs, make sure that they are labeled properly and tape or paste them into this section.

Conclusion

The following information should be entered after you complete the experiment:

Results
Write a one- or two-paragraph summary of the results of the experiment.

Discussion
Discuss, if possible quantitatively, the results you observed. Do your results confirm or refute the hypothesis? Record any thoughts you have that bear upon this experiment or possible related experiments you might perform to learn more. Suggest possible improvements to the experimental procedures or design.

Answer questions
If you’ve just completed a lab exercise, answer all of the post-lab questions posed in the exercise. You can incorporate the questions by reference rather than writing them out again yourself!

Laboratory notebook

A laboratory notebook is a contemporaneous, permanent primary record of the owner’s laboratory work. In real-world corporate and industrial chemistry labs, the lab notebook is often a critically important document for both scientific and legal reasons. The outcome of zillion-dollar patent lawsuits often hinges on the quality, completeness, and credibility of a lab notebook. Many corporations have detailed procedures that must be followed in maintaining and archiving lab notebooks, and some go so far as to have the individual pages of researcher’s lab notebooks notarized and imaged on a daily or weekly basis.

If you’re just starting to learn about chemistry lab work, keeping a detailed lab notebook may seem to be overskill, but it’s not. If you plan to take the Advanced Placement (AP) Chemistry exam, you should keep a lab notebook. Even if you score a 5 on the AP Chemistry exam, many college and university chemistry departments will not offer you advanced placement unless you can show them a lab notebook that meets their standards.

Laboratory notebook guidelines
Use the following guidelines to maintain your laboratory notebook

• The notebook must be permanently bound. Looseleaf pages are unacceptable. Never tear a page out of the notebook.
• Use permanent ink. Pencil or erasable ink is unacceptable. Erasures are anathema.
• Before you use it, print your name and other contact information on the front of the notebook, as well as the volume number (if applicable) and the date you started using the notebook.
• Number every page, odd and even, at the top outer corner, before you begin using the notebook.
• Reserve the first few pages for a table of contents.
• Begin a new page for each experiment.
• Use only the righthand pages, for recording information. The lefthand pages can be used for scratch paper. (If you are lefthanded, you may use the lefthand pages for recording information but maintain consistency throughout.)
• Record all observations as you make them. Do not trust your memory, even for a minute.
• Print all information legibly, preferably in block letters. Do not write longhand.
• If you make a mistake, draw one line through the errorneous information, leaving it readable. If it is not otherwise obvious, include a short note explaining the reason for the strikethrough. Date and initial the strikethrough.
• Do not leave gaps or whitespaces in the notebook. Gross out whitespaces if leaving an open place in the notebook is unavoidable. That way, no one can go back in and fill in something that didn’t happen. When you complete an experiment, cross out the whitespace that remains at the bottom of the final page.
• Incorporate computer-generated graphs, charts, printouts, photographs, and similar items by taping or pasting them into the notebook. Date and initial are add-ins.
• Include only procedures that you personally perform and date that you personally observe. If you are working with a lab partner and taking shared responsibility for performing procedures and observing data, note that fact as well as describing who did what and when.
• Remember that the ultimate goal of a laboratory notebook is to provide a permanent record of all the information necessary for someone else to reproduce your experiment and replicate your results. Leave nothing out. Even the smallest, apparently trivial, detail may make the difference.

Home Chemistry Laboratory

This a list of strictly NOT TO DO STUPID THINGS in a chemistry laboratory:

Never eat, drink or smoke in the laboratory
All laboratory chemicals should be considered toxic by ingestion, and the best way to avoid ingesting chemicals is to keep your mouth closed. Eating or drinking (even water) in the lab is very risky behavior. A moment’s inattention can have tragic results. Smoking violates two major lab safety rules: putting anything in your mouth is a major no-no, as is carrying an open flame around the lab.

Never work alone in the laboratory
No one adult, or tutor or student, should ever work alone in the laboratory. Even if the experimenter is adult, there must at least be another adult within earshot who is able to respond quickly in an emergency.

No horsing around
A lab isn’t the place for practical jokes or acting out, or for that matter for catching up on gossip or talking about last night’s football game. When you’re in the lab, you should have your mind on lab work, period.

Never combine chemicals arbitrarily
Combining chemicals arbitrarily is among the most frequent causes of serious accidents in home chemistry labs. Some people seem compelled to mix chemicals more or less randomly, just to see what happens. Sometimes they get more than they bargained for.

Don’t make explosives
Yes, I know. One that nearly all home chemists have in common is the gene that compels us to make stuff that goes boom, and the louder the better. Resist the temptation. In addition to the obvious danger of losing some fingers – or your head – you risk having DHS agents kick down your door and cart you off to prison. Years ago, it was a rite of passage for home chemists to manufacture explosives, from black powder to nitroglycerin to acetone peroxide. Most (not all) of us survive unscathed, and thought no more about it. The authorities weren’t thrilled about kids blowing stuff up, but they generally resigned themselves to the fact that “boys will be boys.” No more if you’re caught making explosives nowadays – and you probably will be caught if you try it – the best you can hope for is a big fine, and that’s only if you can afford a good lawyer. Just don’t do it.

Laboratory safety is mainly a matter of common sense. Think about what you’re going to do before you do it. Work carefully. Deal with minor problems before they become major problems. Keep safety constantly in mind, and chances are good that any problems you have will be very minor ones.

Classification of matter according to Chemistry

When a person is confronted with a large number of objects or ideas, it is only natural to want to classify and organize them into groups. The advantage of grouping items is that you will end up with a smaller number of groups than objects. In your day-to-day life, you may group baseball cards according to teams or positions. You may organize your books according to titles or authors. At the very least, you probably have a sock drawer. Do you organize your clothes into drawers, according to the type of item? This allows you to remember where you keep your shirts, rather than memorizing where a specific shirt may have been placed.

A good classification scheme will allow you to memorize the characteristics of the groups, which you can then apply to all of the objects in the groups. In other words, rather than memorizing the characteristics of millions of organisms, a biologist will memorize the characteristics of different kingdoms. If an organism is known to belong to a certain kingdom, then the biologist will know some of the characteristics of the organism, based on the known characteristics of the kingdom.

It is important to realize that these classification schemes are manmade, which means that we make up the categories and classes. The classification schemes can change, if someone comes up with a system that scientists like better than the present system. The present classification scheme for chemistry will probably seem very simple and elegant to you, especially if you have recently studied the classification system of biology.

As you can see in the above graphic, all matter can be divided up into four main categories. Of course, there are other ways to classify matter, but this system is the one that seems to be generally recognized right now. Although the diagram is concise, it may not be completely clear unless we read about all of the categories in more detail. Once you understand the categories, the chart should be all that you need to review.

Matter is anything that is made up of atoms, and because all atoms have mass and volume, so does all matter. Even colorless gases, which you can’t see, contain atoms that have both mass and volume. If you doubt that invisible air has volume, blow up a balloon and see how much space the air takes up. All objects that you encounter in your day are examples of matter.

A substance is a type of matter that has a consistent composition. What I mean is that no matter where you find a specific substance, its composition will be the same. In other words, a molecule of water from India has the same composition as a molecule of water from Canada. There is no real variation in the composition of a substance (except, perhaps, on the subatomic level). There are two major types of substances: elements and compounds.

Timing
45 minutes

Description
In this experiment students use simple processes to separate sand and salt.

Apparatus and equipment (per group)

1. 250 cm(3) Beaker
2. Filter funnel and paper
3. Evaporating dish
4. Tripod
5. Bunsen burner
6. Gauze
7. Glass rod for stirring

Chemicals (per group)
A mixture of salt and sand (about 20 percent of salt)

Teaching tips
It can be effective to show the separate sand and salt to the whole class. Mix them at the front of the class, then use this as an introduction to a class discussion about how to separate them.

Background theory
The principles of filtration, evaporation, and the dissolving process.

Answers

To dissolve the salt in water.
The sand is filtered out into the filter paper; the filtrate is salt solution.
To remove the majority of the water.

Introduction
In this experiment simple processes are used to separate salt from a sand and salt mixture.

What to do

1. Mix about 5g of the mixture with 50 cm(3) of water in a 250 cm(3) beaker. Stir gently.
2. Filter the mixture into a conical flask and pour the filtrate into an evaporating basin.
3. Heat the salt solution gently until it starts to ’split’. Care: do not get too close.
4. Turn off the Bunsen burner and let the damp salt dry.

Safety
Wear eye protection.

Questions
Why is the salt, sand and water mixture stirred in step 1?
What happens when this mixture is filtered in the step 2?
Why is the salt heated in step 3?

Chemistry home laboratory

In some ways, a laboratory is very much like a library; but instead of looking up information, the laboratory worker find out about it for himself. In both places the working conditions are similar. Librarians must catalog books in a library and store them in a neat and orderly fashion. Chemists must label their equipment and chemicals in a laboratory and store them in an equally neat and orderly manner. Silence in a library is essential, so the people using it can concentrate on their work. Chemistry tutors say silence is essential in a laboratory too, so the workers can give their complete attention to their work.

For these reasons, and also for the sake of safety and convenience, you will want to find some special place at home in which to establish your laboratory. It must be reasonably quiet and out of everyone else’s way. It must be well lighted and there must be a sink in the laboratory, or very close by, so you can easily get water. To be completely on the safe side, it should be in a place that the younger children can’t get to easily. Your fascinating collection of apparatus and chemicals may tempt them to try things that might prove dangerous.

Once you have chosen a good location you will need these things:

1. A large table on which to perform your experiments. You should cover it with a heat- or chemical-proof substance, such as linoleum, glass or tile. If this is not possible, several layers of newspaper, which you must change regularly will do.
2. Above your work area, there should be one or two shelves on which to keep your chemicals – all, of course, properly labeled and stored, either alphabetically or in groups according to the type of experiment in which you may use them. There is one important exception to this, however. Do not place an acid, such as vinegar, near an alkali, such as ammonia. Enough molecules of each substance can escape even from closed bottles to cause a chemical reaction in the surrounding air. The reaction could contaminate the outside of the bottles and the chemicals nearby.
3. Your laboratory apparatus will include those items which you can make yourself, a few things you will have to purchase, plus many things you can collect, such as baby-food jars, small plastic bottles and corks of different sizes. Keep all of these in separate places on the shelves, or in drawers or boxes which are clearly labeled.
4. Be sure to have at least one ceramic or pottery waste container for discarded, used, or unwanted solid chemicals, for broken glass, and for the remains of successful experiments. To get rid of liquid wastes, you must pour them into a sink, with the water constantly running, or put them into a separate metal waste container.

Your laboratory, like your desk, is essentially yours. It should meet your needs and convenience and should suit your methods of working. It is also your responsibility. You must see that the work you do there doesn’t cause danger, inconvenience, or worry to anyone else.

Above are two pictures of students’ laboratories, one in a garage and the other in the corner of a basement playroom. Either one is a good model.

Equipment you will need
Equipment you may find at home or easily buy:

• aluminium foil
• aluminium pie cans
• apron, rubber or plastic
• asbestos pad
• candles, large and small
• cellophane tape
• cigarette lighter
• coffee can
• colorless nail polish
• construction paper, black
• copper wire
• cord or string
• corks
• dishpan

Everything in this world takes up space and has weight – even air.

The three states of matter are solid, liquid, and gas. This refers to how a thing feels, how hard it is, or how it moves or looks, even if it’s invisible, like air. A table is a solid object, water is a liquid, and air is a gas. These three things are made up of small parts called molecules and even smaller parts called atoms. These small parts are that chemists study and rearrange to create new products that make our lives much better.

Atomie Brew: The Molecule and I
A molecule is the smallest part of anything. You cannot see molecules, but everything in the world is made up of them. The best way to understand this is to imagine yourself shrinking way, way down until you become a molecule. If you were a wood molecule on a tabletop, a salt crystal (one grain of salt) on the table would look like a mountain to you. If you were a molecule of water, you would be the littlest part of a drop. The last part of that water drop to evaporate would be you. But, while molecules are small, the parts that make them up are even smaller. These very small parts that form molecules are called atoms.

If you were a molecule of oxygen, you would be made up of two atoms. You would need two atoms of oxygen, because one atom of oxygen does not behave like oxygen.

A substance with only one kind of atom is called an element. Oxygen, hydrogen, nitrogen, and carbon are all elements. If you were an element of nitrogen, you would be made up of only nitrogen atoms. If you were an element of carbon, you would be made up of only carbon atoms. You could not be anything else.

Atoms of different elements come together to make different molecules. A molecule of water is made up of three atoms. If you were one atom of oxygen, you would have to be joined by two friends representing hydrogen atoms to make a molecule of water, because water has two atoms of hydrogen and one atom of oxygen. You would now be a substance, made up of two (or more) different elements, called a compound. Water, carbon dioxide, and sugar are all examples of compounds. As a molecule you could exit in three possible forms. Chemists would identify you as one of the three states of matter: solid, liquid, or gas.

If necessary, a scientist, or chemist, could again split you apart, using electricity, back into your original parts. Now you would no longer be water but three separate atoms – two hydrogen atoms and one oxygen atom. The very smallest part of you that could ever exist as water would have to be a molecule.

Before you begin chemistry experiments

• Before you begin doing some experiments in chemistry, be smart and do them safely by following these rules:
• Always wash thoroughly any kitchen containers, bowls, or tools you use before you put them back.
• Don’t leave old chemical solutions lying around the house. Dispose of them safely.
• Get an adult to help you perform the experiment. We reiterate, experiments should not be performed without the help of an adult.
• Be sure to label the contents of any bottles, jars, and containers you want to keep, and store them in a safe place, away from young children.
• Make sure you have everything you need and the time to complete the experiment.
• If an experiment may be messy, do it outside or in the sink, or cover your work area with a protective covering such as old newspapers.