James Buch, age 11, of Lancaster, Penn., for his question:
How many elements are there?
So far, 102 different elements have been numbered and named. Some of them are so scarce that only a few ounces exist and some exist for a moment. Polonium, for example, which was discovered by Marie Curie and named for her native Poland, exists only a few seconds or minutes during the rediosetive decay of uranium. Oxygen, on the other hmd, is so abundant that it makes up 21 percent of the atmosphere and half the weight on the earths crust.
Each element is composed of a number of Identical atoms. And each element has a number, the number of proton particles in the nucleus of its item. The lightest element is hydrogen, atomic number 1. The element oxygen, with eight protons in its nucleus, is atomic number 8. The chemical elements found in nature are numbered from 1 to 92 ‑ which is uranium. No element heavier than uranium, it seams, can exist in nature.
Ten elements heavier than uranium have been discovered since 19.0, during and after the making of the atomic bomb. The last of those, nobelium, number 102, was discovered in 1957 end there is no reason why we cannot expect more to be announced. But, as of now, the list of chemical elements stands at 102, 92 of them found in nature and ten discovered in the physics laboratory.
Most of the world is made from just a few of nature’s chemical elements. The element nitrogen makes up 8 percent of the air. Over 36 percent of the weight of the solid earth is nickel and iron, those heavy metals which make up the earths core.
Only ten of the elements are at all plentiful in the earths crust. They are oxygen, found in combination with other elements, silicon, aluminum, iron, calcium, sodium, potassium, magnesium, hydrogen and titanium. Together, these few elements make up over 99 percent of the rocks to a depth of ten miles. With eight more elements, chlorine, phosphorus, mane anose, carbon, fluorine, sulphur, kaium and chromium, we have 99.90 percent of the earth's crust.
Where, then, are the gold, silver and other minerals we know to be chemical elements? All those elements together make up less than ono tenth of one percent of the earth's curst.
Our bodies, too, are made up of chemica1 elements. And here too most of the building work is done by only a few of the natural elements. Old reliable oxygen makes up 65 percent of your body. Carbon makes up 18 percent, hydrogen 10 percont, nitrogen 3 percent, calcium 2 percent and phosphorus 1 percent. These six elements make up 99 percent of your body.
However, we do not find oxygen or any other element in pure form in the body. As in nature, these elements tend to combine to form molecules zind molecules farm substances. The six most plentiful, plus traces of sume 30 other elements, combine to form a variety of body substances. Some of the substances and they way they work held the mysterious secrets of life itself.