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How are chemical compounds different from chemical elements?

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Two diagrams show the three-dimensional structure of a methane molecule: panel A uses a ball-and-stick model with a central carbon atom connected to four hydrogen atoms in a tetrahedral arrangement, while panel B illustrates the bond angle of 109.5 degrees and bond length of 1.09 angstroms between carbon and hydrogen atoms. — chemical compound Methane, in which four hydrogen atoms are bound to a single carbon atom, is an example of a basic chemical compound. The structures of chemical compounds are influenced by complex factors, such as bond angles and bond length.

Chemical elements and chemical compounds are fundamental concepts in chemistry, distinguished primarily by their composition and ability to be decomposed.

A chemical element is a pure substance consisting of only one type of atom that cannot be broken down into simpler substances by ordinary chemical processes. There are 118 known elements, each defined by unique atomic characteristics.123

In contrast, a chemical compound is a substance composed of two or more different elements chemically combined in fixed ratios. When elements form a compound, they lose their individual identities, resulting in a new substance with properties distinct from its constituent elements. For example, hydrogen and oxygen are gases that combine to form water, a compound with entirely different characteristics.13

While elements are the building blocks of matter, compounds are formed through chemical reactions that alter how atoms are organized. Unlike mixtures, which can be separated by physical methods, compounds can only be decomposed into their constituent elements through chemical changes.13