In chemistry: an element — a basic substance consisting of atoms with the same properties (e.g., oxygen, hydrogen) shown in the periodic table.
酸素は元素の一つで、元素記号はOです。
Oxygen is an element; its chemical symbol is O.
元素周期表を覚えるのは化学の基礎だ。
Memorizing the periodic table of elements is fundamental in chemistry.
この試料の元素分析を行った。
We performed an elemental analysis of this sample.
Classical 'elements' — in a philosophical or traditional sense, basic constituents such as earth, water, air, and fire.
古代の自然観では四元素（火・水・風・土）が重要視された。
In ancient views of nature, the four elements (fire, water, air, earth) were important.
文学作品で『元素』という言葉が象徴的に使われることがある。
In literature, the word 'elements' is sometimes used symbolically.
An archaic/literary term meaning origin or source; not commonly used in modern Japanese.
事の元素を明らかにする――というような古い表現が辞書に残っている。
An old expression like 'clarify the element/source of the matter' remains in dictionaries.