Answer:
A chemical compound
Step-by-step explanation:
When two or more elements bond together in specific proportions a chemical compound is formed.
Elements combine in a fixed ratio to form a compound. If the proportion is changed it is a different chemical compound.
Chemical compounds may be formed by combining atoms of specific elements by ionic bonds or by covalent bonds.
Most elements on Earth bond with other elements to form chemical compounds, such as Oxygen (O) and hydrogen (H), wich combined in specific proportion form water H2O. In this example the proportion is 2 atoms of hydrogen and one atom of oxygen, bonded, form water,