Final answer:
Two or more of the same atoms bonded together form a molecule, and if those atoms are different, the molecule is also called a chemical compound.
Step-by-step explanation:
Two or more of the same atoms joined together by a chemical bond is called a molecule. When the atoms are identical, as in molecular hydrogen (H₂), the result is a molecule of an element. However, if the molecule consists of two or more different types of atoms, such as water (H₂O) or methane (CH₄), it is referred to as a chemical compound. The key distinction is that molecules can be composed of the same or different elements, whereas a compound specifically refers to a molecule made of different elements.