What defines a compound?

A compound is defined as a substance made up of two or more different elements that are chemically bonded together. This bonding occurs through chemical reactions, resulting in a new substance with properties that are distinct from the individual elements that compose it. For example, water (H₂O) is a compound formed by the chemical combination of hydrogen and oxygen atoms.

In the context of the provided options, focusing on the definition of a compound highlights the significance of the chemical bonds formed between different elements, which distinguishes compounds from mixtures or single element substances. Mixtures involving pure substances do not involve chemical bonding and can vary in composition, while a combination of only one type of atom does not meet the criteria for being a compound. Similarly, while gases and liquids can be involved in various forms of mixtures or compounds, this does not specifically address the definition of a compound. Consequently, the correct understanding of "two or more elements chemically bonded" appropriately captures the essence of what a compound is.