Description of the Experience
Hydrogen is the first of the elements to be taught in a systematic chemistry. It results from the fact that it is the simplest atom. It is also the first one in a periodic system. The students should already have a detailed knowledge of the periodic table and chemical bonding.
For the time period of 36 years when I have been teaching chemistry, I feel that the students are unable to understand what a chemical bonding constitutes of. My helping tool is writing down the formula of water in the form of structural formula. There they can see 2 bonds. I stress that something must bring those atoms in the molecules together, like when two people give a hand to each other. What is worse, the students do not understand the importance of the genius of the periodic system. They simply perceive it as a guide tool.
They are not able to write notes by themselves. Some I write on the board and the extremely important parts I dictate them. It is a classroom teaching in a form of speaking or telling a "story". The students can freely intervene and ask when they have questions or difficulties with understanding the topic.
First, I ask, what symbol is used for hydrogen. About a third of students react to this question. Then I explain that the translation of the scientific name means "the one who forms water." After follow a few dry facts: it is a gas, in which compounds it is located etc.
Then I start talking about what they could be interested in: it is the most abundant element in the universe, it is a part of stars and nebulae. I point out that Sun is a star as well and that it is filled with hydrogen. Thanks to the reactions that take place there the sun shines. This way I wander off a little into physics.
The history of the discovery is motivational. Hydrogen (H) was discovered in 1766 by an English scientist Cawendish who was a very unique person. He was known to be the most educated out of the richest and the richest out of the scientists.
If he pulled out a book from his own library, he marked it down for himself. He was communicative a very little, lived alone with only a housekeeper in his house. He strictly divided the house into two parts. One only he could move in and the other one where the housekeeper could be moving. Thereby he prevented them to meet each other. However one time it did happen and Cawendish fled with screams of terror.
After his death, his manuscripts were found. They testify how wide his interest also in other fields of science was, but he did not talk with anyone about it. The emphasis of his importance as a scientist is visible in a way that some of the most important physical laboratories are being named after him.
Students also take an interest in learning the way of communicating and information transfer of that time. Because there was no technique, which currently allows instant disclosure of the information, knowledge was disseminated in the form of letters that were usually carried by a messenger on a horseback. A major progress of the issue was marked by the existence of "journals", where new facts were made public, but making these was time consuming and in limited quantity.
The discovery of H shifted the development of natural sciences in a big way. It is the simplest element so therefore it was possible to find out the structure of the atom, which is incidentally named wrongly because "atomos" means indivisible.
The class is also interested when learning that H atom emits energy with a wavelength of 21 cm, on which it would be hypothetically possible to contact extraterrestrial civilizations.
Practical uses of Hydrogen: oxy-hydrogen flame cutting metal in automobile accidents, for example. Here the students recall their experiences and the latest sensations in this area.
This type of experience I consider to be a success-positive. The above-mentioned form of communication interests them.
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Date: 2014.09.30
Posted by Elena Margheri (Italy)
I find this kind of approach to chemistry and science in general very useful, in particular in the first classes of the higher secondary school.
In fact, teenagers of the first and the second years like very much to listen to stories about science, scientists and important discoveries.
It is also a way to let them know how different lives and conditions of scientists and people were in the past centuries.
I usually follow this approach introducing Dalton, Marie Curie and Pauling’s lives describing the experiments about the discovery of subatomic particles.
