John Dalton was an 18th-century scientist who made several significant contributions to his field. One of his most prominent works was his Atomic theory. Dalton’s Atomic theory is a major concept in the study of chemistry. In this post, we will look at this theory and share some of the misunderstandings that Dalton had at his time.
Dalton’s Atomic Theory has four propositions to it.
- All matter is made of atoms that cannot be divided or destroyed
- All atoms of an element are identical in all their properties
- Compounds are formed by a combo of two or more different kinds of atoms
- A chemical reaction is a rearrangement of the atoms in the substance
There is little to explain here. Part one states that atoms cannot be divided or destroyed. In other words, the atom is the fundamental unit of the universe. Part 2 states that all atoms are identical in their properties, which implies that every atom of an element has the same number of protons, neutrons, and electrons.
The third component states that compounds are formed by two or more different atoms. For example, one compound would be H2O which is water. Since there are two elements in H2O, it meets the definition of a compound. We also call such a compound a molecule. Component four states that a chemical reaction is a rearrangement of the atoms in the substance. An example of this would be digestion which involves significant chemical changes to the food.
Problems with Dalton’s Theory
Despite the brilliance of Dalton’s theory, several problems have arisen as researchers have continued to explore the mysteries of chemistry. For example, the first proposition of Dalton states that atoms cannot be divided or destroyed. Both of these claims are false. We now know that atoms are made of protons, neutrons, and electrons. In addition, atoms can be destroyed, which happens at any nuclear power plant through fission. Nuclear fission involves neutrons hitting atoms which causes them to split.
Dalton was also incorrect regarding his second proposition about the same atoms having the same properties. With the discovery of the neutron, it became clear that atoms may have the same chemical properties but not the same physical properties. The reason for this is that having a different number of neutrons affects the atom’s weight. When atoms of the same element have different neutrons, we call these isotopes.
Dalton’s work in the study of atoms is something to be praised. It is understandable that perhaps he got some things wrong. The purpose of science is to grow and improve over time, and this means that sometimes great scientists are right, but they must also be wrong.