Week 2 Reflective Post

Kicking off the week, we dove into the history of the discovery and theories of matter.  We learned that one of the first theories to describe the "stuff" around us was presented by Empedocles, a Greek philosopher and scientist.  He proposed that everything around us was made up of four basic elements.  Fire, Water, Earth, and Air.  Although back then people didn't have our current understanding of matter, this theory was an important development in scientific thinking because it was the first one to say that things were mad up from a combination of different elements.  The rest of this article on matter summarized the discoveries and theories other older chemists and philosophers had.  One of the most important theories in this packet was Dalton's theory of matter which had four main concepts.
1. All matter is composed of indivisible particles called atoms.
2. All atoms of a given element are identical; atoms of different elements have different properties.
3. Chemical reactions involve the combination of atoms, not the destruction of atoms.
4.When elements react to form compounds, they react in defined, whole-number ratios.
Dalton's theory was a very important stepping stone for the future discoveries in the concept of matter.

Unit 4 Worksheet 3 was a very important part of this week.  It was the first worksheet we had that covered mass ratios in different compounds.  During this worksheet, we compared two different compounds which had different ratios per atom.  Then we compared the ratio of the first compound with the ratio of the second.  For example, in the first problem the ratio of the first compound was 4/3.  That meant that for every 4 oxygen atoms there was 3 carbon atoms.  We then compared this to the ratio of the second compound which was 8/3.  After comparing the two we concluded that the first compound and the second compound are related by a ratio of 2:1.  After this first problem we did a couple more of these problems which helped solidify our understanding of the comparing of mass ratios.

Yet another important science history lesson we covered was the story behind the discovery of Iodine.  To summarize the article, there was a race between two scientists to uncover the element of Iodine.  Humphrey Davy was an english scientist who along with Joseph-Louis Gay-Lussac discovered Iodine.  I thought this article was very interesting because it portrayed the conflicts between the two scientists and also the differences in their learning/discovery methods.  It really helped me in learning the scientific material because I had plenty of background material that made the learning more interesting for me.

One of the last things we covered was Worksheet 4 of unit 4.  Fairly similar to worksheet 3, it covered ratios and percentages of elements in a compound.  We were able to find the percentages of certain elements in a specific compound by knowing how many grams of each element were in the compound.  This worksheet was very helpful as it gave me specific examples of how compounds are composed of different elements.  It was really informative and I'm glad we did it.

Overall, these concepts all connect with each other and help us finish our comprehension of chapter 4.  The beginning articles on the discovery of what matter really, is helped shape our understanding into a better picture.  From there, the worksheets helped us use that new knowledge of matter and apply it to scientific problems.  I think that this week I learned and understood some of the concepts better than I did last week because I engaged more in the learning process.  This also helped because almost all of the questions I had were answered by these different articles and worksheets.  I'm excited to journey into our next unit of chemistry.