Final answer:
Compounds are held together by chemical bonds such as polar covalent bonds, non-polar covalent bonds, hydrogen bonds, and ionic bonds, forming molecules with atoms from at least two different elements.
Step-by-step explanation:
Compounds are substances that are composed of molecules consisting of atoms from at least two different elements. These elements are held together in a compound by chemical bonds. There are several types of chemical bonds that can hold compounds together, including polar covalent bonds, non-polar covalent bonds, hydrogen bonds, and ionic bonds.
A simple example of a compound is water (H₂O), where oxygen and hydrogen atoms are held together by polar covalent bonds, while a more complex compound like sodium chloride (NaCl), commonly known as table salt, is held together by ionic bonds.