What is meant by element

The concept of element in chemistry


Elementary substances or elementary atoms

When working with a "Periodic Table of the Elements", the term element is used in different meanings. Gold is commonly referred to as an "element". There are several meanings for this term. If you look at an element representation in the periodic table with the physical quantities (in the picture above for gold, bottom right) such as density, melting point or boiling point, then you actually mean the properties of the "elementary substance" (according to Robert Boyle). The ordinal number 79 means the number of protons in an "elementary atom" (according to IUPAC). The atomic mass at the top left is an average value, calculated from the naturally occurring isotopes according to their abundance. In a common periodic table, the information is used either for a substance or for atoms, depending on what is considered.

The four elements in ancient times and in alchemy

The term element was used in ancient times. The Greek philosopher Empedocles distinguished four “principles”: fire, earth, water, air and fire. Aristotle assigned properties to these four elements. According to Aristotle, the fire is warm and dry, the earth dry and cold, the water cold and damp, the air damp and warm. Alchemy took over the concept of element from Aristotle. The alchemists also saw certain principles in the four elements. They believed that the metals, like the four elements, are mutually convertible.

Elementary substance after Boyle

In 1661, Robert Boyle (1627–1691) questioned in his famous book The skeptical chemist the theory of the four elements and discussed experimental results. With the help of numerous experiments, he proved that gold, mercury and copper cannot be broken down. According to Boyle, an item is one elemental substancewhich cannot be further broken down into two or more other substances. All other substances are chemical compounds.

An elementary substance can no longer be transformed without a reaction partner, unless its internal organizational structure is destroyed with the help of modern nuclear physics. The compound water can be produced from the elementary substances hydrogen and oxygen. A production or synthesis of water takes place when one burns hydrogen in the air. In the analysis, the decomposition of water into its elementary substances with electric current with the help of electrolysis, one gets hydrogen and oxygen again from the connection hydrogen oxide:

Hydrogen + oxygen → hydrogen oxide (water)
Hydrogen oxide → hydrogen + oxygen

Principles according to Lavoisier

Antoine Lavoisier (1793–1794) supported Boyle's results experimentally, so that the theory of the four elements of antiquity was finally refuted. However, like the alchemists, he believed that chemical "Principles“Are included. In contrast to Boyle, the elements in Lavoisier are not chemical substances as they are used today.

Elementary atome according to IUPAC

In this usage, the “element gold” or the “element carbon” are the elementary atoms meant. For example, a gold atom always has 79 protons and 79 electrons and has the electron configuration [Xe] 4f145d106s1Strictly speaking, one would have to speak of the "Periodic System of Elemental Substances (Boyle) and Elemental Atoms (IUPAC)". The term “element” would actually be superfluous, but it is so common in parlance that it cannot simply be ignored. One should only be aware of the distinction when speaking of the "periodic table of the elements".

Further explanations: History of the Periodic Table by Peter Buck

Create a book individually: Basic text element term


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