| Unit 2: Chemistry |
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From the table of chemical formulas, you can see that carbon dioxide is a compound of carbon and oxygen. There are two atoms of oxygen for every atom of carbon. Sodium hydrogen carbonate (sodium bicarbonate) is a compound of sodium, hydrogen, carbon, and oxygen. There are three atoms of oxygen for every atom of the other elements. Also, there are a total of three atoms in the carbon dioxide formula and a total of six atoms in sodium hydrogen carbonate.
To generate the gas to fill the empty eggshell in this activity (the teacher demonstration), zinc was placed in hydrochloric acid. Zinc is an element. Hydrochloric acid (HCl) is a compound of hydrogen and chlorine. The reaction of the zinc and hydrochloric acid created a gas. Given the explosion you observed, you can guess that the gas produced was hydrogen. The hydrogen gas came from the hydrogen in the hydrochloric acid.
There’s much more to the structure of matter than you can discover in just one activity. However, this activity may have raised some new questions in your mind. For example:
- Can all compounds be decomposed into their elements?
- What techniques can be used to decompose compounds?
- What are elements made of?
- What are atoms?
- What are molecules?
These questions and many more will be explored in other Active Chemistry activities. |
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Checking Up
1. In your own words, explain the difference between an element and a compound.
2. Why are symbols useful in describing chemical elements?
3. What are the symbols for the following elements: carbon, copper, gold, and helium?
4. What information does a chemical formula of a compound provide?
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| Reflecting on the Activity and the Challenge |
| Part of the problem you are facing in creating a special effect is understanding what matter is made of and how it can change. In this activity you broke a chemical compound down into its component elements using electrolysis. In another part of the activity a compound was made from chemical elements through a fast and noisy reaction. There are only about one |
hundred elements, but there are many thousand compounds. You should begin thinking of ways in which some of the reactions you observe could be made to appear more dramatic on screen, without making them any larger in real life. You can now use the concepts of elements and compounds to provide the chemistry description of what is occurring. |
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