What is the chemical definition of an element?

The chemical definition of elements refers to more than one hundred basic metal and non-metallic substances in nature. They are composed of only one kind of atom, and their atomic nuclei have the same number of protons. They cannot be made by ordinary chemical methods. Decomposes and can constitute all matter.

Some examples of common elements are hydrogen, nitrogen and carbon. As of 2012, 118 elements have been discovered worldwide, 94 of which exist on earth. The nuclei of elements with atomic numbers ≧83 (bismuth and later) are unstable and undergo radioactive decay.

Elements 43 and 61 (technetium and promethium) do not have stable isotopes and will decay. However, even elements with atomic numbers as high as 95 and without stable nuclei can be found in nature. This is the natural decay of uranium and thorium.

Extended information:

Historical origins of elements:

The idea of ??elements originated very early. The ancient Babylonians and ancient Egyptians once regarded water (and later regarded it as Air and earth), regarded as the main elements of the world, formed the three-element theory. The ancient Indians had four major theories, and the ancient Chinese had the five elements theory.

The theory of elements, that is, the theory that regards elements as the simplest components that constitute all real objects in nature, has been produced as early as ancient times. However, the modern concept of elements as concrete forms of matter did not exist in ancient times. Whether in ancient Chinese philosophy or in ancient Indian or Western philosophy, elements are regarded as an expression of abstract, primitive spirit.

Ancient Greek natural philosophy proposed the famous theory of four elements. This was not created by Greek philosophers. The theory of the four elements existed in the traditional folk beliefs of ancient Greece, but it did not have a (relatively speaking) solid theoretical system support. Ancient Greek philosophers "borrowed" the concepts of these elements as essences.

Baidu Encyclopedia—Elements