“A recurrent theme that’s oft taught in
Gen Chem 1 is the theory of Dalton.
In a chemical change,
Matter will rearrange:
One of key points presented each autumn.”
In the 27 April 2019 limerick, I returned to discussing common themes of my introductory chemistry lecture course. In this case, the subject is Dalton’s Atomic Theory. John Dalton was an English scientist who completed many fundamental studies in chemistry, biology, and meteorology in the late 1700s and early 1800s.
“A recurrent theme that’s oft taught in /
Gen Chem 1 is the theory of Dalton.”
General Chemistry 1 introduces three perspectives on chemistry: the particulate-level (what are atoms and molecules in a chemical sample doing?); the macroscopic-level (what can we observe about that sample in the laboratory, as a result of the behaviors of the component atoms and molecules?); and the symbolic (how do we represent both of these levels via equations and other notation, to best communicate with other scientists?). These three perspectives are summarized as Johnstone’s Triangle (or the chemistry triplet) and learning to translate among the three can be a challenge for students. Dalton’s Atomic Theory is a common theme in General Chemistry 1 and highlights some links between each of the three “sides” of this triangle.
“In a chemical change, / Matter will rearrange: /
One of key points presented each autumn.”
Dalton’s Atomic Theory is a set of statements about chemical behavior. Several of these statements rationalized behaviors about chemical species that had already been observed by other scientists. Others predicted behaviors that would later be observed, leading to the theory’s acceptance. The theory rationalizes matter’s behavior (macroscopic perspective) through the concepts of atoms and compounds (particulate perspective). The theory is generally presented as a set of multiple postulates, one of which states that a chemical reaction rearranges matter but does not create or destroy it. This idea is a statement of the conservation of mass and is summarized by the last three lines of the limerick; further, it is only one of several “key points.” These chemical changes are represented (symbolic perspective) with balanced chemical reactions, as described in the 3 April 2019 limerick.
Chemphasis 