In middle school, students are progressing in their knowledge of what matter is, what it is made of, how it behaves and changes, and how it can be manipulated. These phenomena are the nature of chemistry. So why not use the term “chemistry” with students and celebrate National Chemistry Week? This year the American Chemical Society (ACS) celebrates its 20th National Chemistry Week. Their purpose is to increase awareness of the role chemistry plays in daily life.

A good example comes to us from Science Daily, 100 Years Of Ammonia Synthesis: How A Single Patent Changed The World published October 6, 2008. This story argues that the ability to combine atmospheric nitrogen with hydrogen to make ammonia (NH₃) had a revolutionary impact on the course of human history.  This is because it made mass production of “fixed” atmospheric nitrogen possible–something up until then only bacteria could do at nature’s pace. This meant more food production in more parts of the world where agriculture had not been successful previously. Greater food availability enabled world population growth.

Structural formula for ammonia from http://www.eou.edu/chemweb/molmodel/images/nh3fc.gif

A second use for ammonia besides fertilizers is explosives. This application for ammonia can be perceived as having the opposite effect on human populations that fertilizers seemed to have had.

The process used to make ammonia is called the Haber-Bosch method, named after two individuals who perfected it in 1909. They were awarded Nobel prizes: Haber in 1918 and Bosch in 1931. Were either Haber or Bosch fully aware of the potential impacts of their technological innovation on society? Most likely no. The history of science is full of stories of unintended consequences.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

The National Science Education Standards in physical science, history and nature of science, science and society and science and technology can be tapped through use of this article. If your students have studied biogeochemical cycles, then you can activate their prior knowledge and ask them how useful atmospheric nitrogen is to living things. Facilitate their recollection of the need for soil bacteria and fungi in converting atmospheric nitrogen into useful compounds for plants. Make sure they  understand nitrogen is an important component of proteins and DNA. The only way for people to obtain needed nitrogen is through the food we eat.

If students have not studied the nitrogen cycle yet, then inform them that nitrogen makes up 70% of the air we breathe, yet we exhale it right back out, it is of not use to us. However,  nitrogen is needed for us to grow. It is an important component of proteins and DNA. The only way for people to obtain the nitrogen we need is from what we eat, because in that form it is useful to us.

Ask them if they can think of ways that farmers enhance or improve their crops in order to maximize yield. Students will probably be able to come up with the idea of adding fertilizer. Ask them if they know what the main ingredients of fertilizers are. They are nitrogen, phosphorus and potassium, three elements found on the periodic chart, and which are crucial to plant growth.  Obviously the form of nitrogen in the fertilizer is not atmospheric since it is a solid, not a gas, at room temperature. Tell them the nitrogen has been “fixed” in a chemical factory in the same way that bacteria normally fix it, in the soil. Ask if they can think of any advantage of being able to accomplish nitrogen fixation in a factory. They will realize it is the ability to mass produce it faster than bacteria can do it.

Emphasize this represents a technological innovation: a case where knowledge of the elements nitrogen and hydrogen obtained through scientific investigations was applied to enhance the quality of life, to solve a problem. Then ask if technology can also introduce unintended consequences?  Use air pollution from automobiles as an example. Could the ability to mass produce fertilizers with the compound ammonia, NH₃ also have some unintended consequences? Allow for plenty of wait time. They may not view more food as an unintended consequence. Lead them to connect more food to more people surviving and reproducing. What does that cause?

Let them know the same nitrogen compound, ammonia, found in fertilizers is also found in explosives.  What unintended consequences are seen around that issue?

Wrap the discussion up emphasizing the relationship between science and technology, the impact of science and technology on society and the impossibility of anticipating all the impacts of any scientific advancement. We must be careful not to unduly criticize former pioneers when to us it appears their contributions seem to have had unwelcome impacts. We must keep in mind those pioneers did not have the benefit of hindsight as we do today. In the same way, we have an obligation to think as creatively as we can, engage in as much conversation with as many diverse individuals as we can in order to better anticipate the probable impacts of proposed scientific or technological innovations.

Here are additional related resources from the National Science Digital Library Middle School Portal: The Nitrogen Cycle; Chemistry: Making it Real;  and Technology and the Environment

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