Part 2: Fundamental Chemistry—Elements

All matter is composed of elements. Three main categories of elements exist:

1. Metals. Metals are solid materials that typically possess a hard texture, shiny appearance, high density, and good conductivity of electricity. Metals also possess the unique physical characteristics of malleability and ductility. Examples of common metal elements are iron, lead, copper, and gold.
2. Metalloids. Metalloids are elements with characteristics of both metals and non-metals. Because of their ambiguous definition, there is some disagreement throughout the chemical community about which elements fall under this classification. Some elements commonly classified as metalloids are silicon and boron.
3. Nonmetals. Nonmetals do not possess metallic characteristics and are instead readily volatile. Opposite of metals, they also serve as excellent insulators. Examples of nonmetal elements are hydrogen, oxygen, nitrogen, and carbon.

Although 118 elements exist, only 92 are found in nature. The remaining elements have been created in a laboratory environment but are chemically unstable and therefore exist for only very short periods of time.