Final answer:
An example of a pure substance that is an element is copper (Cu), a metallic element with its own set of unique properties, unlike compounds like water (H2O) which are made of two or more atoms and exhibit new characteristics.
Step-by-step explanation:
Example of a Pure Substance of an Element
When discussing pure substances in chemistry, we categorize them as either elements or compounds. An example of a pure substance that is an element is copper (Cu). Elements are the simplest forms of matter and cannot be broken down into any simpler substance through chemical means. Copper, for instance, is a metallic element with a characteristic reddish-brown color and is used in various applications such as electrical wiring and coins. It is one of the 118 elements known to science, which include other familiar ones like iron, carbon, and gold. Unlike mixtures, pure elements have a fixed composition and a unique set of physical and chemical properties that remain unchanged throughout the sample.
Contrast this with compounds, which are substances formed by chemical bonds between two or more different types of atoms. Water (H2O), for example, is a compound made of hydrogen and oxygen atoms in a fixed ratio. Whereas elements showcase their own definitive characteristics, compounds can exhibit entirely new properties not reflected by their individual elemental components. To understand the distinction, imagine combining sodium, a reactive metal, with chlorine, a toxic gas, to form sodium chloride (table salt), which bears neither the reactivity of sodium nor the toxicity of chlorine.