Pure & Applied

Chemistry

I. The Scientific Method

More and more in our global society, people are realizing that many facets of their daily lives are quite dependent upon numbers, numerical relationships, and universal laws. If we do not have a working knowledge of science and mathematics then we empower others to make scientific decisions that may affect our personal and professional lives.

Mathematics has been referred to as the “universal language”. While only a few of the letters of the English alphabet are used (primarily as variables, such as the x, y and z coordinates of the 3-d Cartesian coordinate system), most of the elements which constitute the “mathematical alphabet” are Greek letters or mathematical symbols. Prime examples of this are the symbols used to express the basic mathematical operations of addition, subtraction, multiplication, and division.

The exchange of ideas using mathematical principles and symbolism is an intellectual activity which is as old as any literary endeavor known to man. Advances in math and science have evolved gradually over the past several centuries, with notable influence by the original thinking of a French philosopher named René Descarte.

Descarte believed that the universe is composed of basic particles or elements which can be isolated and viewed independently from one another. He attempted to put the whole universe on a rational mathematical foundation by introducing the concept and theory of mechanism -- thereby reducing the study and description of the known universe to simple problems of mechanics and mechanical measurement. 

Later on, the western world was introduced to the basic tenets of the Scientific Method. We learned about systems of units and measurement (e.g. grams, meters, seconds) which have been standardized and accepted so that students and scientists across the globe can communicate effectively with each other.  This allowed us to solve story problems involving such variables as distance, weight and time, and to apply the fundamental principles of the Scientific Method in real life situations.   

In order to approach this website, you should understand the definition of physical properties as being the properties characteristic of any given object, substance, or material. Physical properties may provide conclusive evidence of the chemical composition of a given sample of material. Such characteristics may include odor, color, volume, density, melting and boiling point, physical form (solid, liquid or gas), mechanical hardness and tensile strength.  Such properties may be instrumental in the identification of physical evidence which has been obtained at the scene of a crime.

You should have a good understanding of systems of measurement, including the standard units used in the quantitative measurement of such physical parameters as length (or distance), area, volume, mass and time. You should memorize the unit prefixes which are used to express positive and negative powers of ten in the metric system. You may even need to review concepts of ratio and proportion as being the relationship between two separate quantities (e.g. density = mass / volume).

II. Chemistry

Chemistry is the study of the nature, properties, and composition of matter, and how these undergo changes. Chemistry plays an important part in all of the other natural sciences, basic and applied. Plant growth and metabolism, the formation of igneous rocks, the role played by ozone in the atmosphere, the degradation of environmental pollutants, the properties of lunar soil, the medical action of drugs, establishment of forensic evidence: none of these can be understood without the knowledge and perspective provided by chemistry. Indeed, many people study chemistry so that they can apply it to their own particular field of interest.

Chemistry is a way of studying matter. It is often said that matter is anything which has mass and occupies space. But then what are "mass" and "space"? Although we can define these, the process yields very little insight into what matter is. So let us just say that matter is anything which has real physical existence; in a word matter is just stuff. Iron, air, wool, gold, milk, aspirin, monkeys, rubber, and pizza - these are all matter. Some things which are not matter are heat, cold, colors, dreams hopes, ideas, sunlight, beauty, fear, and x-rays. None of these is "star stuff". None is matter.

A sample of matter can be either a pure substance or a mixture. A pure substance has a fixed, characteristic composition an a fixed, definite set of properties. Pure substances are for example copper, salt, diamond, water, table sugar, oxygen, mercury, vitamin C, and ozone. A pure substance may be a single element, such as copper or oxygen, or a compound of two or more elements in a fixed ratio, such as salt (39 % sodium and 61 % chlorine) or table sugar (42 % carbon, 7 % hydrogen, and 51 % oxygen).

A mixture is a collection of pure substances simply mixed together. Its composition is variable, as are its properties. Examples of mixtures are milk, wood, concrete, saltwater, air, granite, motor oil, chocolate, and elephants.

A pure substance can be a solid, a liquid, or a gas; these are the three states of matter A solid maintains its volume and shape; a liquid, its volume only; and a gas, neither. Solids tend to be hard and unyielding; liquids maintain their volumes and flow to adopt the shapes of their containers. The ability to flow is called fluidity, and so gases and liquids are called fluids.

One of the goals of chemistry is to be able to describe the properties of matter in terms of its internal structure -- the arrangement and interrelationship of its parts. The word 'structure' sometimes refers to the physical arrangement of particles, such as atoms or molecules in space. At other times it is used to indicate some other arrangement, such as the arrangement of energy levels of an electron in an atom.

Interestingly, the structure of matter determines its properties. Properties can be classed as either physical or chemical. A physical property of a substance can be characterized without specific reference to any other substance and usually describes the response of the substance to some external influence, such as heat, light, force, electricity, etc. Physical properties include boiling point, melting point, thermal (heat) conductivity, color, refractive index, viscosity, reflectivity, hardness, tensile strength, and electrical conductivity.

A chemical property, on the other hand, describes a chemical change: the interaction of one substance with another , or the change of one substance into another. Iron rusts in a moist environment, unrefrigerated milk turns sour, wood burns in air, photographs bleach when exposed to sunlight for a long time, dynamite explodes - each of these is a chemical property because each involves chemical change. During chemical changes, substances are actually changed into other substances. The simultaneous disappearance of some substances (called the reactants) and appearance of others (the products) is characteristic in chemical change (chemical reaction). Chemical changes are generally characterized by pronounced internal structural rearrangements, including the breaking of chemical bonds (the reactants) and the formation of new chemical bonds (the products).

Physical changes are not characterized by the transformation of one substance into another, but rather by the change of the form of a given substance with no change in chemical composition. The bending of a piece of copper wire fails to change the property of copper into another substance. Crushing a block of ice leaves only crushed ice. Melting an iron nail yields a substance which is still compose of pure iron. These are all typically accepted as physical changes.

Properties of matter may also be categorized as either macroscopic or microscopic. A macroscopic property describes characteristics or behavior of a sample which is large enough to see, handle, manipulate, weigh, etc. A microscopic property describes the behavior of a much smaller sample of matter, such as an atom or molecule or a  grouping of such particles. Macroscopic and microscopic properties are often different. A banana is yellow, but we do not use color to describe an atom. Some properties, on the other hand, can be either microscopic or macroscopic (e.g. mass). 

The periodic table of the chemical elements is a tabular method of displaying the chemical elements. Although precursors to this table exist, its invention is generally credited to Russian chemist Dmitri Mendeleev in 1869. Mendeleev intended the table to illustrate recurring ("periodic") trends in the properties of the elements. The layout of the table has been refined and extended over time, as new elements have been discovered, and new theoretical models have been developed to explain chemical behavior.

The periodic table is now ubiquitous within the academic discipline of chemistry, providing an extremely useful framework to classify, systematize and compare all the many different forms of chemical behavior. The table has also found wide application in physics, biology, engineering, and industry. The current standard table contains 117 elements as of 27 January 2008.

The main value of the periodic table is the ability to predict the chemical properties of an element based on its location on the table. It should be noted that the properties vary differently when moving vertically along the columns of the table than when moving horizontally along the rows.

A group is a vertical column in the periodic table of the elements. Groups are considered the most important method of classifying the elements. In some groups, the elements have very similar properties and exhibit a clear trend in properties down the group these groups tend to be given trivial (unsystematic) names, e.g., the alkali metals, alkaline earth metals, halogens and noble gases. Some other groups in the periodic table display fewer similarities and/or vertical trends, and these have no trivial names and are referred to simply by their group numbers.

A period is a horizontal row in the periodic table of the elements. Although groups are the most common way of classifying elements, there are some regions of the periodic table where the horizontal trends and similarities in properties are more significant than vertical group trends. This can be true in the d-block (or "transition metals"), and especially for the f-block, where the lanthanides and actinides form two substantial horizontal series of elements.

III. Nanotechnology

Modern chemical synthesis has reached the point where it is possible to prepare small molecules to an infinite variety of structure, purpose and function. These methods are used today to produce a wide variety of useful chemical compounds such as pharmaceuticals or commercial polymers. This raises the question of extending this kind of control to the next length and size scale, seeking methods to assemble these single molecules into supramolecular assemblies consisting of many molecules arranged in a carefully controlled manner.

These approaches utilize the concepts of molecular self-assembly and/or supramolecular chemistry to automatically arrange themselves into some useful conformation through a bottom-up approach. The concept of molecular recognition is especially important. I.E. Molecules can be designed so that a specific conformation or arrangement is favored due to various intermolecular forces. The Watson-Crick base pairing rules for nucleic acids (e.g. DNA double helix) are a direct result of this, as is the specificity of an enzyme being targeted to a single substrate, or the specific folding of the protein itself. Thus, two or more components can be designed to be complementary and mutually attractive so that they make a more complex and useful whole.

Such bottom-up approaches should be able to produce devices in parallel and much cheaper than top-down methods, but could potentially be overwhelmed as the size and complexity of the desired assembly increases. Most useful structures require complex and thermodynamically unlikely arrangements of atoms. Nevertheless, there are many examples of self-assembly based on molecular recognition in biology besides nucleic acids. The challenge for nanotechnology is whether these principles can be used to synthesize novel biomaterials in addition to natural ones.

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I have been teaching the fundamental Principles of Chemistry for over 10 years now, both Online and in the live classroom.  I find that there is nothing more satisfying -- and I truly hope that you find this website to be helpful to you in some aspect of your both your personal and professional lives :-)

 Enjoy !

 ~ Professor Bob ~

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Online Publications:

Silica

Sol-gel

Biomaterials

Crystal growth

Crystal structure

Ceramic engineering

Transparent ceramics

Transparent materials

Light scattering

Strength of glass

Physics of glass

Glass transition

Colloidal crystal

Kinetic theory of solids

Spinodal decomposition

Transformation toughening

Plastic deformation in solids

Phase transformations in solids

Solids

Liquids

Last Updated:  03 / 01 / 10