Blog #6

This past week we started understanding what positive and negative charges looked like in atoms. We did a sticky tape lab where we charged pieces of tape to see what they attracted. On the hanging dowel we had a piece of foil, paper, and two pieces of charged tape (one that was on top and one on bottom). We then took two other pieces of tape, stuck them together and then ripped them apart to give them a charge. We took the top piece labeled T and put it near the samples on the dowel. We noticed that it attracted the foil, paper, and bottom tape, but repelled the top tape. We then took our bottom charged tape and saw that it attracted the foil, paper, and top tape, but repelled the bottom tape. From this we made some conclusions. There are three rules: 1. The same charged substances repel each other. 2. Opposite charges attract. 3. Neutral charged substances like foil and paper do nothing when they are put next to each other. We found this last rule by putting a piece of paper closer to the hanging foil and other piece of paper on the dowel. When doing this nothing happened, showing that they are neutral. From this lab, we concurred when charging the two pieces of tape together, the top piece has a positive charge and the bottom piece has a negative charge. When we put our hand close the the two tapes before they become charged, they don’t attract or repel because our hands are neutral, and the tape stuck together is neutral as well. However when we put our hand closer to the charge tapes after they have been taken apart they attract each other, since opposites attract! Below is a picture of us conducting the experiment.

Along with this experiment we looked at compounds that combine metal and nonmetal particles that do not conduct electricity as solids. We came up with formulas for many different compounds such as CaO, Al2S3, BeS, and Na2s. After writing them out, w e drew particle drawings for each. After this we looked at a portion of the periodic table that covered all of the elements we used. We wrote all of the chemical formulas we came up with in their corresponding element boxes. For example for the chemical formula CaO, we wrote in in the Ca box and the O box. This helped us find a pattern that wasn’t so easy to see at first. What we found is that the elements in the first row on the table have a +1 positive charge, then the next row was +2, then +3, +4, and then switched to -3, -2, -1, and finally 0. I saw that in a formula such as Li20, both elements have to equal out, so if there are +2 Li’s then there has to be -2 O’s, so they cancel each other out. Below is a picture of what the periodic table looked like with all of the formulas in it. You can take any formula and figure out what charge the elements have by making sure they equal each other out.

In all, my understanding of how charge works if definitely a lot better than when we started this unit. By understanding the basic rules of charge, I can predicted and hypothesize if two things will repel, attract, or do nothing. I would rate my overall understanding at a 7 probably, because there still are some aspects I don’t completely understand: like how many atoms have to be in particles that are oppositely attracted to each other.