Element Definition

What is an Element?

An element is a pure substance consisting of only one type of atom which all have the same numbers of protons in their nuclei.

The question of the conceptual nature of the term “element” represents a rather unique opportunity to examine the relationship that currently exists between chemists and philosophers of chemistry.

The chemical element was first presented by the English scientist Robert Boyle. He defined an element as a substance “incapable of decomposition” and like a true scientist added the prophetic by any means with which we are now acquainted. Boyle’s definition comes admirably close to present-day theory. Elements have been changed in the laboratories of today, though not by any chemical means.

Related Topics

• Introduction to Elements & Compounds
• Periodic Table of Elements
• 118 Elements and their Symbols
• Difference Between Element and Compound
• Classification of Elements and Periodicity in Properties
• Transition Elements

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Origin of the Elements

A young American chemist named F.W.Clarke stated in 1873: “It is probable that the chemical elements were originally developed by a process of evolution from much simpler forms of matter as is indicated by the progressive chemical complexity observed in passing from the nebulae through the hot stars to the cold planets.

Clarke attempted to prove his hypothesis by representing the relative abundance of the elements by a curve taking their atomic weights for one set of ordinates. He had hoped that some sort of periodicity might be evident but no such regularity appeared and no definite connection with the periodic law seemed to be traceable.

Yet certain other regularities were worth noticing; all of the abundant elements were low on the scale of atomic weight, reaching a maximum of 56 in iron. Above 56 the elements were comparatively rare, and only two of them, barium and strontium, appeared in Clarkes estimates.

Geochemical Classification of the Elements

Goldschmidt stated that based on the existing data on the affinity of various elements for oxygen and sulfur, we can obtain a geochemical classification of the elements. From the free energy of the formation of oxides combined with the free energy of the formation of various elements with iron, he drew up a list of elements which are concentrated in the iron phase of meteorites and probably also in the supposed iron core of the earth. He called these elements siderophile elements or elements tending to concentrate in metallic iron. Typical examples are nickel, cobalt and the metals of the palladium and platinum groups.

A second group is formed by those elements which have greater free energy of oxidation, per gram of oxygen than iron. To these elements, Goldschmidt gave the name lithophile elements or elements tending to concentrate in the stony matter. They concentrate in the stony matter of the earth, as well as in the stony matter of meteorites as oxides or silicates.

The third group is formed by elements concentrated in the sulfide phases of meteorites such as troilite and Goldschmidt called them chalcophile elements. Elements which occur either in the uncombined state such as oxygen nitrogen and rare gases etc. or volatile compounds. According to Goldschmidt, they are atomophile elements. Finally, we can distinguish the biophilic elements which are concentrated in and by living plants and animals.