Academic journal article The Science Teacher

Our Molecular Selves

Academic journal article The Science Teacher

Our Molecular Selves

Article excerpt

Have you heard about the amazing physical properties attributed to an elderly hermit living in the Andes Mountains of South America? When he inhales, approximately 10,000,000, 000,000,000,000,000 ([10.sup.22]) atomic particles make up each full breath he takes. This is astounding, for that many particles greatly exceeds the total number of humans who ever walked on Earth!

Still more atomic particles, some [10.sup.23] of them, exist in each cubic centimeter of his bones. That is more than the number of drops of water in all the lakes and rivers of the world. Furthermore, each of these skeletal particles dances continually in a state of perpetual motion expected to continue even after the hermit dies.

Is this hermit extraordinary? Maybe in some ways, but his physical properties are ordinary. You and all your students possess the same physical properties.

We are Stardust

The universe as we know it has approximately 100 different kinds of atoms. The lightest and most numerous is hydrogen, followed by helium, then in succession to the heavier atoms of uranium. Our bodies are composed of atoms. Where do these atoms originate? Most were made in the innards of stars that exploded eons ago in faraway galaxies, long before the birth of our solar system. The atoms comprising our bodies are the dust of ancient stars. So we are but dust, and unto dust we shall return. You can truthfully say that special someone is literally stardust (Figure 1).

We are all one

Atoms combine to become molecules. About 80% of the molecules in the atmosphere are nitrogen, and most of the rest are oxygen. Molecules composing Earth's atmosphere are so numerous that on average about [10.sup.22] molecules are in each liter of air. Remarkably, Earth's entire atmosphere consists of the same number ([10.sup.22]) of liters. So there are almost as many molecules in a breath of air as there are breaths of air in Earth's atmosphere (Figure 2).

Even more remarkable, the molecules you exhale are not the exact same ones you inhale. Some inhaled molecules stick to your insides and become part of you, many of which you later exhale. The sniff of a dog who recognizes your smell verifies that your exhaled breath is indeed part of you. This becomes fascinating: In each breath you inhale are molecules exhaled by those around you and by others. …

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