The Classification of Matter

Matter is classified in one of three ways:

1. Elements
2. Compounds
3. Mixtures

Elements

Elements is the most basic of all matter. Elements are pure substances that have a set of unique properties and cannot be further broken down or decomposed into other elements by chemical methods. There are some 111 different elements or more depending upon the time that you read this. Each element differs in the kind of atom particle that makes up the elemental substance. Each element has a different atom from other elements differing in the number of sub-atomic particles (electrons, protons, and neutrons). Each atom is symbollically distinguished by a specific symbol to represent the element. These symbols were not always as standard and defined as they are now. At one time in midieval Europe the alchemist,the fore runner of the present day Chemist, used a set of symbols to represent the elements. The only problem is that there were no one set of symbols agrreable to all Alchemists. A man by the name of Berzelius and people like him realized that unless scientists had a common symbol table to use, communication would be garbled at best. Therefore a set of symbols were decided upon to be used by all concerned. At first, these symbols were based on the Latin word for the known elements in that day. We may think that the symbol for Hydrogen comes from the English word for Hydrogen, but it originated from the latin word which happens to have the first letter an "H". Latin was used because during the renaisance, Latin was the accepted language among the clergy and intellectuals of that time. With the passage of time, other sources were used to select a symbol. Greek and Roman Methology is used such as Plutonium and Helium named after the Greek God of the Sun, Helios. Neptunium named after the ancient God of the Sea, Neptune. Other sources were famous geographical settings such as Californium and Berkylium. Still others were named after distinguished scientiests such as Einsteinium, Fermium, and Mendeleevium. The names and consequent symbols for the elements require international collaboration to decide upon a name and symbol for newly discovered elements. Sometimes disagreements over what names will apply arise. For instance, just recently the American Chemical Society and the IUPAC have a disagreement over some of the Newer Elements.

The atoms of a specific element can differ in the number of neutrons that the nucleus of the atom possesses. These different "forms" of the element are called Isotopes. The atoms of all the isotopes of a single element will have the same number of electrons and protons, but their neutrons and therefore their masses will differ. It is the statistical distribution in nature along with the isotopic mass of each Isotope that will decide the atomic mass of the element itself.

Elements chemically combine their atoms to produce another form of matter called the compound.

Compounds

Compounds are pure substances having a unique set of properties that are produced when elemental substances chemically combine. Unlike elements whose numbers are finite, the number of compounds theoretically possible are limitless. Compounds are symbolized by a formula which is the use of the symbol for each element represented in the compound and subscripts that appear right after the symbol of the element. The subscripts have a duel purpose. They can be interpreted as the number of atom particles making up a single unit of the compound. However a more practical interpretation of the subscript is to represent the number of mole units of the element in each mole unit of the compound. Compounds interact with each other when brought into contact. Compounds can be ionic consisting of ion particles. Compounds can also be molecular composed of molecular units instead of ionic units. Ionic compounds are usually as a result of Metallic elemets chemically combining with Non-metallic elements. Molecular compounds are formed when Non-metallic or Metalloid elements chemically combine with each other. Compounds are much more varied to study. When we physically combine elements and/or compounds together we get a third kind of matter, a mixture.

Mixtures

Mixtures are physical combinations of two or more elements or compounds. Being physical combinations, mixtures can be separated by using a difference in a physical property between the pure substances in the mixture. This is called Resolution of the Mixture and results in the physical separation of the componenets in the mixture.

There are three kinds of mixtures.

1. Heterogeneous
2. Homogeneous
3. Colloids

Heterogeneous mixtures are mixtures where the compoents are not uniform in their distribution throughout the mixture. The division between the components in such a mixture can be easily seen. Such mixtures can often but not always be separated by filtration or the use of a separatory funnel. If we take a sample of such a mixture the sampling will not always show the same distribution of each component in the mixture. For this reason, we say that the mixture is not uniform i its composition.

Homogeneous mixtures are uniform in their distribution. If we took a sampling anywhere in the mixture, and then analyzed it as to its composition for each component we would find that the distribution was the same throughout the mixture. All solutions are said to be Homogeneous mixtures.

Colloids are sometimes classified as a heterogeneous mixture. However, unlike a heterogeneous mixture whose components will separate, colloids are mixtures whose components will not easily separate out. This is because the size of the particles making up the mixture are not large enough for gravitational force to pull them apart. The particles can't be seen as in the case of a heterogeneous mixture, but the particles of a colloid will scatter a beam of light passed through the colloid. This scattering of light by the particles is called the Tyndall Effect and it is a property of colloids. Colloids can not be filtered since the particles are small enough to pass through the tiny openings of the filter paper. Colloids can be destabilized by removing charged particles that are responsible for keeping the particles from becoming larger. Electrostatic precipitators are devices that can destabilize a colloid and cause the components to separate. Heterogeneous mixtures have the largest particles, followed by colloidal particles. The smallest particles are found in homogeneous mixtures such as solutions. These particles are too small to be seen as in Heterogensous mixtures and too small to scatter a beam of light passed through the mixture as a colloid exhibits in the Tyndall Effect.