For today’s starter activity, students were challenged to draw the molecular structures represented by the chemical equation for cellular respiration:
C6H12O6 + O2 -> H2O + CO2 + ATP
Many students were able to draw molecular oxygen (O2, with a double bond between the two oxygen atoms), water, and carbon dioxide (also with double bonds connecting the central carbon atom to the two oxygen atoms). The molecular structure of glucose (C6H12O6) was far more challenging. We transitioned into Lesson 32, which brought together the concepts of molecular structures, valence electrons, covalent bonding, and Lewis dot symbols. We reviewed the Lesson 32 PowerPoint and then students worked in groups of four to complete the Lesson 32 worksheet. To help students visualize molecular structures, we used the molecular modeling kits. The kits were especially helpful in helping students understand double and triple bonds.
The Lesson 26 PowerPoint introduced students to the four models of chemical bonding. Students also received a handout of the models with additional information. After the PowerPoint, students worked in pairs to organize the Substance Cards and recorded their learning on the Lesson 26 worksheet (one per student pair).
Note: worksheet question #8 asked students about elemental substances. We did not have time at the end of class to explore the topic, so we will discuss briefly tomorrow during class. Examples of elemental substances are molecular oxygen (O2) and molecular hydrogen (H2), both of which consist of two covalently bound atoms of the same element. An elemental substances consists of two or more atoms of the same element.
After spending the first half of class reviewing the DNA base pairing worksheet from Tuesday, we moved ahead with a survey of molecular bonds. We focused on covalent and hydrogen bonds, with water molecules as our model molecules. Students used the molecular modeling kits to model the interactions of water molecules at different temperatures before moving on to modeling the interactions of DNA nucleotides. The lesson can be downloaded here.