What is an element?

An element is defined as a pure substance that cannot be broken down into simpler substances through chemical means. Elements are the fundamental building blocks of matter and are made up of only one type of atom. Each element is identified by its specific number of protons in the nucleus of its atoms, known as the atomic number. This property distinguishes one element from another.

In contrast to elements, organic compounds, which consist of carbon in combination with other elements (often hydrogen and oxygen), are more complex and can be broken down into simpler substances. Similarly, mixtures involve a combination of two or more substances that retain their individual properties and can be separated physically. Lastly, a complex structure made of various compounds refers to materials formed from multiple components, which also do not qualify as elements. These concepts outline clearly why C is the accurate definition of an element in chemistry.