The question of how many elements exist in nature yields two distinct answers, depending entirely on the context: ancient philosophy or modern science. The word “element” has undergone a profound transformation, moving from a conceptual substance meant to explain the terrestrial world to a clearly defined atomic entity. Understanding this historical shift is necessary to reconcile the small number of elements proposed by early thinkers with the large number recognized by contemporary science. This difference in definition marks the boundary between a philosophical model and an empirically determined structure of matter.
The Classical Four Elements
For nearly two millennia, the Western world operated under a model where all terrestrial matter was composed of just four classical elements: Earth, Air, Fire, and Water. This concept was first systematically proposed by the Greek philosopher Empedocles in the fifth century BCE. These elements were not viewed as the pure chemical substances we know today, but rather as idealized forms of matter. The varying properties of physical objects resulted from different combinations and proportions of these four elements.
The philosopher Aristotle later formalized this system by associating each element with a combination of two opposing qualities: hot, cold, wet, and dry. Fire was hot and dry, Air was hot and wet, Water was cold and wet, and Earth was cold and dry. This framework explained change, suggesting that one element could transform into another by shifting a single quality. For instance, water (cold and wet) could become air (hot and wet) by gaining heat.
The Concept of Aether
The classical worldview often included a fifth element, known as Aether, or Quintessence. This element was considered distinct from the four earthly elements and was not part of the terrestrial realm. Aether was posited as the pure, unchangeable substance that composed all heavenly bodies.
Unlike the four terrestrial elements, Aether was defined by the absence of the qualities of hot, cold, wet, or dry. Aristotle proposed that Aether’s natural motion was perfect circularity, which explained the uniform movement of celestial objects. This fifth substance distinguished the flawless, eternal heavens from the mutable world of Earth, completing the ancient philosophical model.
Defining a Modern Chemical Element
The modern scientific definition of an element is radically different and is based on the subatomic structure of an atom. A chemical element is a species of atom uniquely defined by the number of protons contained within its nucleus. This number is known as the atomic number, represented by the symbol Z. Every atom with the same number of protons belongs to the same element, regardless of how many neutrons or electrons it possesses.
For example, every atom of carbon possesses exactly six protons, giving it an atomic number of Z=6. Changing the number of neutrons results in a different isotope, but the atom remains carbon. Only a change in the number of protons—which occurs through nuclear reactions—transforms the atom into a different element altogether. This proton-based definition provides a clear standard for classification, formalized and organized by the Periodic Table. The table arranges elements sequentially by their increasing atomic number, allowing scientists to predict chemical behavior based on position.
The Current Number of Elements
Based on the modern scientific definition, the total number of recognized elements is currently 118. These elements are organized on the Periodic Table, beginning with hydrogen (Z=1) and ending with oganesson (Z=118). This total count includes elements found naturally on Earth and those artificially created in laboratories.
The majority of known elements, specifically the first 94, occur naturally on Earth, though some exist only in trace amounts due to radioactive decay. The remaining 24 elements, from atomic number 95 (Americium) onward, are synthetic. These are produced by scientists using nuclear accelerators, a process that involves smashing atomic nuclei together at high speeds to create new, heavier elements, which are often highly unstable. Since the process of creating new elements is ongoing, the number 118 is not a final figure and may increase as researchers synthesize heavier atoms.