Element vs. Compound — What's the Difference?

Elements are pure substances that cannot be broken down into simpler substances by chemical means. Each element is characterized by a unique type of atom, distinguished by its atomic number, which is the number of protons in its nucleus. Compounds, on the other hand, are substances formed when two or more elements are chemically bonded together in a fixed ratio, resulting in properties that differ from those of the individual elements.

While elements are the basic building blocks of matter, compounds are more complex structures that result from the chemical combination of these building blocks. For example, oxygen (O) is an element that consists of O atoms, whereas water (H2O) is a compound made from hydrogen and oxygen elements in a 2:1 ratio. This distinction highlights the simplicity of elements and the complexity of compounds.

The properties of an element are uniform throughout because they are made of the same type of atoms. Compounds exhibit properties that are unique and often significantly different from the elements that constitute them. For instance, sodium is a highly reactive metal, and chlorine is a poisonous gas, but combined as sodium chloride (NaCl), they form table salt, which is safe for consumption and has entirely different properties.

In terms of classification, elements are organized into the periodic table based on their atomic numbers and properties, such as metals, non-metals, and metalloids. Compounds, however, are classified based on the types of chemical bonds that hold their atoms together, such as ionic, covalent, or metallic compounds.

Elements can exist in various forms, including atoms and molecules (e.g., O2, which is molecular oxygen), but they remain the same element. Compounds require a chemical reaction for formation and another chemical reaction for separation into their constituent elements, indicating a more complex chemical behavior compared to elements.