found as galena? Some important metallic minerals are: hematite (a source of iron), paarite la source of aluminum), and galina (a source of lead). Q3. (Optional) How many electrons are there in the outer shell of Carbon, Aluminum and Chlorine? These are the valence electrons: Carbon 4 valence electrons Aluminum: 3 valence elections Chlorine: 7 valence electrons Component 5: Lesson Conclusion The focus of this lesson was about pure substances in chemistry using examples of many different elements, the lesson was also about retrieving information from tables. Q1. Has this lesson helped you to better understand the differences between atoms? If so, how? Q2. Has this lesson helped you to remember the names and symbols of common elements? If so, how 3. Which questions were easy to answer - the ones in Component 48 or Component 4C? Why?