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Chemistry Fundamentals

Chemistry Fundamentals

Six important factors are important to the understanding of chemistry.

  1. Structure
  2. Acids and Bases
  3. Attraction
  4. Stability
  5. Reactions
  6. Equilibrium
Structure

This term to refers to the manner in which the atoms that compose a molecule of a specific compound are attached (bonded) to one another and oriented in space.   Information on how atoms are attached, and to some extent how they are oriented, is provided by a structural formula i.e a lewis dot structure; Three important aspects of structural formulas are:

  • Composition: The kinds and numbers of atoms that compose a molecule of a compound.
  • Constitution: The manner in which the component atoms of a molecule are bonded to each other. Different compounds having the same composition but different constitutions are called isomers.   The prefix iso is from the Greek word for "the same or alike".
  • Configuration: The shape of a molecule in three-dimensional space.   Isomers differing only in configuration are called stereoisomers.




Acids and Bases

Robert Boyle in the seventeenth century first identified substances as either acids or bases (he called bases alkalis)....

Acids are compounds which include hydrogen atoms.   When they are dissolved in water they release hydrogen ions (H+) into solution.   A typical acid is hydrochloric acid (HCl)

Bases dissolve in water to release hydroxide ions (OH-) into solution.   A typical base is sodium hydroxide (NaOH):

This subject is covered on a separate web page...Acids-Bases


Attraction

Opposite electrostatic charges (plus & minus) are attracted to each other, and like charges repel.  Such charges are produced by removing (or adding) electrons from (or to) an object.   Charged atoms or molecules are called ions, and the principle of attractions and repulsion governs their interactions. ref Ions - Cations

Many organic reactions are influenced by a similar factor. Electron deficient species, which may or may not be positively charged, are attracted to electron rich species, which may or may not be negatively charged.



Stability

Stability implies an object, system or situation that is likely to remain unchanged for a significant period of time.   In chemistry, two kinds of stability are important.

  • Thermodynamic Stability: ... The potential energy of a compound relative to a reference state.
  • Chemical Stability:... The resistance of a compound or mixture of compounds to chemical change.
(More notes to follow)



Reactions

Chemical reactions are the heart of chemistry.   A chemical reaction is when one or more substances are changing into other substances.   Reactions are identified in chemistry using simple equations.  An example reaction equation, of iron reacting with oxygen in the corrosion process, is provided below;

The reactants are shown on the left of the equation and the products are shown on the right.  The law of conservation of mass states there is no loss of mass in the reaction process.  The number of atoms of each element will therefore be the same on both sides of the equation.

It is important first to define the components of a reaction.   It is also necessary to understand that several competing reactions may take place in a given system, and their relative velocities (rates) will generally influence the composition of the products.

This subject is covered on a separate web page...Chemical Reactions



Equilibrium..

Many chemical reactions are reversible.   This means they may proceed in both directions (from reactants to products, or from products to reactants).   As an example consider the reaction below ..

The reactants and products are both gases. At the temperature of the reaction (20 deg. C) the products are not totally stable and there is the simultaneous reaction taking place as follows..

This type of reaction is said to be reversible and is indicated as follows..


In such cases as the one shown above an equilibrium state occurs, in which the rates of the two reactions are identical.   An equilibrium always favors the more thermodynamically stable side of the equilibrium.   
(More notes to follow)


This subject is covered on a separate web page...ref. Equilibrium Notes



Relevant links..
  1. Fundamentals of chemistry...A very good starting point
  2. Chemguide Helping you understand chemistry... Menu driven site introducing most chemistry topics
  3. Organic Chemistry Online... Very professional site useful for students
  4. AP Chemistry -Study Cards... A set of chemistry study cards- Ideal look up revision aids
  5. Sparknotes chemistry study guides... A comprehensive set of study guide blocks

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Last Updated 28/01/2013