Dalton’s atomic theory. The main ideas of this theory (model) can be stated as follows:Dalton’s Atomic Theory1. Elements are made of tiny particles called atoms.2. All atoms of a given element are identical.3. The atoms of a given element are different from those of any other element.4. Atoms of one element can combine with atoms of other elements to form compounds. A given compound always has the same relative numbers and types of atoms.5. Atoms are indivisible in chemical processes. That is, atoms are not created or destroyed in chemical reactions. A chemical reaction simply changes the way the atoms are grouped together.Dalton’s model successfully explained important observations such as the law of constant composition. This law makes sense because if a compound always contains the same relative numbers of atoms, it will always contain the same proportions by mass of the various elements.Like most new ideas, Dalton’s model was not accepted immediately. However, Dalton was convinced he was right and used his model to predict how a given pair of elements might combine to form more than one compound. For example, nitrogen and oxygen might form a compound containing one atom of nitrogen and one atom of oxygen (written NO), a compound containing two atoms of nitrogen and one atom of oxygen (written N2O), a compound containing one atom of nitrogen and two atoms of oxygen (written NO2), and so on (Fig. 4.2). When the existence of these substances was verified, it was a triumph for Dalton’s model. Because Dalton was able to predict correctly the formation of multiple compounds between two elements, his atomic theory became widely accepted.