When many atoms combine to form a larger structure, we call this __________.

When many atoms combine to form a larger structure, the term that best describes this formation is a molecule. A molecule is defined as two or more atoms that are chemically bonded together. These atoms can be of the same element or different elements, and they can be held together by covalent bonds, where electrons are shared between the atoms.

The understanding that a molecule is the product of multiple atoms bonding together is crucial in chemistry, as it lays the foundation for understanding more complex structures. For example, water (H2O) is a molecule formed from two hydrogen atoms and one oxygen atom bonded together. This concept is distinct from other choices listed.

While elements are pure substances consisting of only one type of atom, and compounds are made up of two or more different types of atoms chemically combined, the focus here is on the combination of many atoms, which specifically refers to molecules. Ions, on the other hand, are charged particles that result from the loss or gain of electrons and are not necessarily formed by the combination of many atoms.

In summary, the creation of larger structures through the combination of multiple atoms aligns perfectly with the definition of a molecule, making it the correct answer.