Until the 16 th Century, men of science solved problems based upon a hap hazard trial and error approach. Furthermore, the successes and failures of scientific endeavor were doomed to be repeated because of the lack of documentation. Very little documentation was preserved. Sir Francis Bacon along with other people of vision helped to develop a methodical, systematic approach to solving problems. Since these were people of Science, this was to be known as the "Scientific Method". However the scientific method is used to solve any problem or to help make any decision.

The scientific method is not really rigidly chiseled in stone. It is more of a process by which you proceed in advancing knowledge, solving problems, or making decisions. It basically begins with a defined problem, task, or decision. The problem must be researched to determine who else has worked on the problem, the successes, the partial successes, and the outright failures. Traditionally, this research has been conducted in the sanctity of a library, but that seems to be rapidly changing. With the advent of searchable on-line databases that document virtually all of documented human achievement, one can search the depths of human experience in the comfort of a room. Now, with the discovery of the InterNet and the World Wide Web, documented human experience and accomplishments are at our fingertips.

Once the problem has been researched, the investigator can now determine an educated guess as to a solution to the defined problem. This educated guess is referred to as the hypothesis. Once the hypothesis has been formed, it must be tested under controlled conditions. An experiment is a test performed in a controlled environment called a laboratory. The experiment must be carefully designed so as not to bias the hypothesis. A carefully designed experiment includes identifying what parts of the experiment can change either at will or by design. Such changeable parts are called "variables". There are two kind of variables, dependent and independent. Independent variables are variables that are allowed to change by design. Their changes are premeditated by the experimenter. Dependent variables are variables that change as a response to premeditated changes of the independent variables. For example, if we should investigate the two variables of volume of a gaseous substance and its temperature. We might choose to manipulate the temperature change and then measure the volume changes that occur as a result of the temperature changes. The temperature variable would be called the independent variable while the volume change would be the dependent variable. Of course, such a designed experiment to investigate the volume and temperature variables would require that the designer identify what parts of the experimental design should remain fixed in value. These would be called the constants. Our study of the volume and temperature variables would require that we hold the amount of gas and the pressure fixed or constant. In addition to the defining of variables and constants, measurements must be made so instruments of measurement must be identified in the experimental design. The instruments must be calibrated so that the measurements made will be reliable and reproducible.

Once the experimental design is complete, the experiment must be performed paying close attention to the design parameters. Observations are made which can be collected and reported as data. The observations can be one of two types. Qualitative observations are made by our senses. These kind of observations are extremely subjective. There is no reproducibility with qualitative observations. This is a major drawback when it comes to collecting data. A good set of quantitative measurements must be reproducible, valid, precise, and accurate. Reproducibility is measurements that are capable of being repeated within an acceptable range of deviation. Validity is measuring what is intended to be measured. If we use a thermometer to measure mass, then our measurements will be totally invalid. Precision is an internal consistency in a series of measurements. If the set of measurements are very closely spaced to one another then the measurements are said to be very precise. An analogy of precision is the throwing of darts. If three darts are thrown at a dart board, and the darts hit in pretty much the same area of the board, then we say that the throws were very precise. Accuracy is an external consistency of measurements based on a standard. Again, the analogy of the dart throws can be considered. If one of the three throws hits the bulls eye then we would say that that particular throw was accurate with the bulls eye being the external standard that we measured the accuracy of the throw with. For a set of measurements to be good they should be reproducible, valid, precise, and accurate.

After the measurements have been made an analysis of the data should be made. This can take the form of a simple comparison of two sets of data or as sophisticated as a computer analysis. Once the data has been analyzed, conclusions can be formulated which will either accept the hypothesis as an acceptable solution to the defined problem or it will reject the hypothesis whereupon an alternative hypothesis must be selected and the process repeats itself.

We use the scientific method in one form or another whether we realize it or not virtually daily. Whether it is to listen to radio reports of traffic in the morning or the weather reports, we process this data in an effort to make a decision as to what we will wear and how we shall travel to work or school.

Chemistry is defined as an organized body of knowledge concerning the composition of matter and how matter interacts and changes . Matter can be defined as anything that possesses the properties of mass and volume. Mass is the measure of a chunk of matter's ability to resist a change in movement or direction. The chemist calls this "inertia". Volume is the three dimensional space occupied by matter. It is a universal axiom that two chunks of matter can not occupy the same space simultaneously. All matter is composed of basic particles of atoms, molecules or ions.

The basic of these particles are the atom. Atoms are particles that are composed of three sub-atomic particles. The three sub-atomic particles are the proton, neutron, and the electron. The proton is a positively charged particle that has the mass approximately equal to a hydrogen atom. It is said to have the mass of 1 atomic mass unit (amu). The protons reside in the nucleus or center of the atom. The neutron is a neutrally charged particle that is approximately the mass of a proton. The neutron does not have an electrical charge, but it also resides in the nucleus. The particles of the nucleus are called nucleons. The third particle of an atom is the electron. The electron is a negatively charged particle of negligible but finite mass. It resides on the outer edges of the atom with an enormous amount of space between the nucleus and the electrons.

Because the protons and the neutrons are relatively well protected in the nucleus and the electron is on the periphery of the atom, it is the electrons that undergo change during a chemical reaction. It is the electrons that the chemist focuses upon. It takes millions of times more energy for the nucleus to be penetrated so the nucleus is not affected in normal chemical reactions. Atoms are neutral so that means that the positive protons and the negative electrons must be equal for the atom to be neutral. There are some 111 known different atoms that are differentiated by two numbers, atomic number and mass number. The atomic number is equal to the number of protons found in the nucleus. For a neutral atom that would also be the number of electrons in the atom. The mass number is defined as the sum of the protons and the neutrons in the nucleus of an atom. In other words, the mass number is the number of nucleons found in the atom. If I know the atomic number of an atom and the mass number then I can determine the number of electrons, protons, and neutrons that the atom has.

Molecules are clusters of atoms that are held together by strong electrical forces called bonds. Molecules are neutral like atoms. Substances that form molecular units are called molecular substances. Just as elements can be symbolized by a symbol, molecules can be symbolized by the symbols of the elements that make up the compound. These are called formulas. Non-metallic elements react with other non-metallic elements to form molecular compounds

Ions are the third basic particle of matter. Ions are charged atoms or groups of atoms possessing an electrical charge. Atoms are neutral possessing equal numbers of negative electrons and positive protons. However some atoms have a tendency to lose one or more negative electrons during a Chemical change. If the atom loses electrons that would mean that the atom would have more positive protons than negative electrons and the atom would become positively charged. These ions are called "cations". Metallic elements tend to lose electrons and become cations.

Other atoms prefer to gain one or more negative electrons. This would give such an atom more negative electrons than protons and the atom would be negatively charged. These are referred to as "anions". Non-metallic elements have atoms that tend to gain electrons to become anions.

The whole motivation of why some atoms lose and some gain electrons is to make the atoms chemically more stable. They gladly sacrifice their electrical neutrality in favor of a more stable state. The more stable state is an ion that has the same number of electrons as one of the noble gases found in the last column of elements on the right of the periodic table. This condition is referred to as being "isoelectronic" to a Noble gas. These elements used to be called the "inert gases" because there were no known compounds of these elements. These elements are still relatively inert which is a testament of their great stability. All other elements have atoms that would like to emulate these noble gases. In other words, to be isoelectronic to a Noble Gas. The Noble gases were found to react with certain very chemically reactive elements like Fluorine and Oxygen and only Xenon has been known to form compounds of Fluorine and Oxygen. It is not surprising that such relatively stable elements would react with these two non-metals (Fluorine and Oxygen) If they were to react it would be the two most reactive non-metals in the universe.

All atoms would like to have the same number of electrons as a Noble gas because of their great stability. In order to accomplish that, some atoms must lose one and some more than one electron in order to have the same number of electrons as the nearest Noble Gas in the Periodic Table. For the first column of elements called Group 1 located in the first column on the left side of the Periodic Table each element in this Group have atoms that have only one electron that needs to be lost in order to reach this isoelectronic state with the nearest Noble Gas located on the last column on the extreme right of the Table called Group 18. The second column of elements in the Periodic Table called Group 2 has elements whose atoms have two electrons that must be lost to become isoelectronic to the nearest Noble Gas. On the other end of the Periodic Table, there are Groups of elements like Group 15 where atoms must gain three electrons in order to become isoelectronic to the nearest Noble Gas. Group 16 elements have atoms that must gain only two electrons to become isoelectronic to the nearest Noble Gas. Group 17 elements which are only one column to the left of the Noble Gas Group requires that its atoms need only to gain one electron.

Matter can undergo two major kinds of Changes.

Physical Change is a change where there is no change in the composition of the substance and only the physical state of the substance takes place. Examples include the melting of a solid, The freezing of a liquid, sublimation of a solid to a gas, formation of a solution, evaporation, boiling process, crystallization, etc. In a physical change the molecular particles remain unchanged and no fragmentation of the molecules take place. Physical changes may be accompanied with energy being absorbed or given off during the physical change.

Chemical change involves a change in the composition as well as the physical state (perhaps). In a chemical change molecules fragment and recombine to form new molecules with a different composition. Evidence of Chemical Change include formation of evolution of gas at room temperature, the formation of a precipitate at the mixing of two solutions. Examples of Chemical Change include the souring of milk, fermentation, combustion (burning), cooking of foods, metal corrosion, electroplating of objects, etc.

Whenever we wish to understand a phenomenon that is occurring in real life, there are two basic viewpoints with which we can view the phenomenon whether it be a chemical change or physical change.

One view in which we can perceive such a change is the "sub-microscopic" view. This view is what I call the "molecular" view. It is a view that we can only hope to envision with our mind's eye. We can't actually view the particles (molecules or ions), but by envisioning molecules and atoms dynamically where the particles are in constant movement we can better understand what is actually happening.

The second view is called the "macroscopic view". This view is a view that we observe in the world around us. It is what we observe in a laboratory as we observe chemical and physical changes.

The relationship between the two viewpoints is important. Often we can't really understand what we are viewing macroscopically until we have developed a sub-microscopic or molecular view of that change.

There are a number of clues that will point to a Chemical change taking place. A chemical change will take place when the molecules or ions of matter undergo rearrangement or fragmentation where in many cases the fragments recombine to form new molecules or ions. The bottom line from a molecular view is that molecules undergo change in structure or shape. However from a "macro-scopic" view, the view that we can see in the laboratory what are some laboratory observations?

1. A rapid evolution of bubbles at room temperature.

   This usually indicates that a new gaseous substance is being formed where the substance was not present to begin with.

2. A solid forms upon the mixture of two chemical solutions.

   This is called "precipitation". Do not confuse this with another process that takes place which would be described as a physical change, solidification or crystallization. When a pure liquid becomes a solid, a solid does appear (macroscopically), but this is the physical change of liquid molecules into more rigidly fixed solid molecules. Since the molecules are the same (whether in the liquid or solid state) no chemical change is taking place.

   A precipitation also results in a solid appearing (macroscopically). However the solid is caused as a result of two solutions (containing ion particles) being brought together. Two of the ions of opposite charge get together and a new substance is formed which is insoluble in the solvent present (usually water). This results in the new substance appearing as a solid. Since the new substance was not present before the change took place this would be described as a chemical change. The precipitate upon further examination of its properties would have a different property profile.

3. Energy is being exchanged (absorbed or liberated). However, we have to be very careful with this observation since physical changes can also involve energy exchanges. The important thing is that if we reverse the energy exchange that the pure substances before and after the energy exchange are the same. How can we know that the pure substances are the "same"? That brings us to our fourth observation.

4. The measurable properties of a pure substance before the change will be altered to a new value after the change if the change is truly a chemical change.

   Every pure substance (elements and compounds) have a set of measurable properties such as melting point, boiling point, density, etc. I call this its' "property profile" of the pure substance. If the property profile is altered after the change has taken place then we can suspect that a new pure substance is present and a chemical change has apparently taken place. For example, if we have a pure substance "A" and a change takes place where the boiling point of a pure substance "B" is measured and is shown to be different than the boiling point of substance "A", then we have to conclude that a new substance "B" has formed that was not there initially.

Mixtures are physical combinations of two or more pure substances (elements or compounds). As a physical combination one should be able to separate these substances from the mixture by physical methods so that no Chemical change can take place during the separation. Substances can be separated from the mixture by taking advantage of any differences the substances have in physical properties. For example, most pure substances have different boiling points (temperature at which a substance will boil). If we can heat a mixture so that the lowest boiling substance will boil off before any other substance begins to boil, we will effectively be able to separate that substance from the mixture. One such laboratory resolution method is known as distillation. There are several different types of distillation.

1. Simple Distillation- This form of distillation is best used when you have pure substances that you wish to separate that are 100 degrees or more apart in boiling point. Basically, it consists of a boiling flask in which the mixture is placed. The flask is connected to a distilling head with a thermometer inserted into its top. The distilling head is connected to a water cooled condenser which ,in turn, is connected to a recepticle where the pure substance that was boiled off would be found.

   The flask is usually heated by either a bunsen burner or a heating element called a Heating Mantle. Heating Mantles are used when there is a danger of vaporous substance igniting due to the presence of a burner flame.Other forms of heating are a water bath that is heated by a hot plate surface or a steam bathg where live steam is the source of heating. Milder and more controllable form of heating is the water bath, but it is only capable of heating up to 100 degrees Celsius.

   The flask is heated until the boiling point of the lowest boiling substance in the mixture is reached. Then the substance will vaporize and travel over to the condenser whose inner core is cooled by circulating water from the cold water tap. Water travels in at the bottom of the condenser and comes out at the top. As the hot vapors of the substance come into contact with the water cooled surface of the condenser core, the vapor will lose its energy it gained from being heated in the flask and will condense back into a liquid which will be pure in the lowest boiling substance in the mixture. The closer the boiling points of the substances are in the mixture, the more likely that the vapor coming over into the condenser will be partially of the two substances. If the substances within the mixture are within 60 degrees of one another, simple distillation techniques are not very efficient and a second type of distillation must be considered.

2. Fractional Distillation-Fractional Distillation is similar to simple distillation except for one very important extra item in the set-up. We have a vertical column that is inserted in between the distilling flask and the distilling head called the "fractionating column". This column is ,unlike the condenser, never heated. It is usually filled with glass beads or metal wire mesh inside its central core. Quite often, it is insulated using spun glass which is stuffed into the center of the column. This provides many surfaces for the vaporized substances to condense upon. As the mixture is heated the substances that are nearest to each other in boiling point will both vaporize. The vapor mixture will then rise into the fractionating column and will condense on the relatively cooler surface and the hot condensate will fall back into a lower portion of the column only to be met with hot vapors from below and the hot vapors will re-vaporize the liquid back into the vapor state pushing the mixture vapor even higher up the fractionating column where it will be recondensed and the cycle repeats itself over and over again. Each time the vapor mixture gets richer in the lower boiling substance. By the time it reaches the distilling head at the top of the fractionating column the vapor is pure in the lower boiling substance. Actually, each time there is a vaporization followed by a condensation, a simple distillation is being performed. Fractionating columns are rated in "theoretical plates". A theoretical plate equal to 1 is the same efficiency as one simple distillation. Usually theoretical Plates of 4 or 5 are considered good since that would yield the same efficiency of separation as if you had simple distilled each successive distillate (that which was distilled over) 4 or 5 times in succession.

   Often, the fractionating columns are wrapped in thermal insulation and even heated at the bottom of the column while gradually cooled at the top.

3. Vacuum (Reduced Pressure) Distillation- Often a mixture contains a pure substance which will have such a high boiling point that it will chemically decompose before it reaches its boiling point. This is obviously self defeating. However, boiling points vary according to the atmospheric pressure. The lower the pressure the lower the boiling point will be for the same substance. If the pressure inside the distilling flask could be reduced thereby reducing the boiling point below the decomposition point, then the substance could be effectively separated from the mixture. Vacuum distillation is also used when you have to separate a highly volatile and combustible solvent that has a low flash point. By reducing the pressure inside the flask you could effectively distill such a solvent without using even a heating mantle or hot plate. Just the warmth of the body temperature would be sufficient to separate it!!
4. Steam Distillation- An alternative way of distilling a liquid substance whose normal boiling point (boiling point at 760 mm Hg) is above its decomposition point is steam distillation. A substance must be insoluble (immiscible) in water. It must also have a polar group that could be attracted to the water molecule. Oils and tars are steam distillable. The advantage over vacuum distillation is that you don't have the excessive "bumping" that takes place in the vacuum distillation. The ancient Egyptians marketed a rose oil that was separated from rose petals by essentially a steam distillation process. The rose oil was at one time considered as valuable as its weight in Gold!! The distillate that comes over is actually two immiscible liquids, water and the organic substance. This is referred to as a "co-distillate". The organic by itself might boil hundreds of degrees Celsius but will come over with the steam at or below 100 degrees Celsius.

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