A. an element and two compounds, B. two elements and a compound, QUESTION: Consider the pictorial representation shown below for the molecular composition of a mixture. Using Dalton’s atomic theory, the figure represents a mixture of A. an element and two compounds, B. two elements and a compound, C. three compounds SCRIPT: Consider the pictorial representation shown here for the molecular composition of a mixture. Using Dalton’s atomic theory, the figure represents a mixture of A. an element and two compounds, B. two elements and a compound, C. three compounds PAUSE According to Dalton’s theory, an element is only made of one kind of atom. We can see that we have One set of molecules here that are made up of just two small circles. HIGHLIGHT If we were to separate these molecules from the mixture, we would have a pure sample of an element. We also have one set of molecules that are made up of just two big circles. HIGHLIGHT If we were to separate these molecules from the mixture, we would have a pure sample of another element. Finally, we have a set of molecules consisting of one big circle and three small circles. If we were to separate these molecules from the mixture, we would have a pure sample of a compound. The molecules of the compound are made of two elements in a well defined ratio. Therefore, the correct answer is B… two elements and a compound. CLICK PAUSE END RECORDING

Video ID: 1-13-4 © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08