Barry Gofstein, age 11, of Portland, Maine, for his questions

Exactly how many elements are there?

All the things in our everyday world are made from 92 different chemical elements. The scientists have discovered a few more in the laboratory and a few existing only during the fury of an atomic explosion. This has brought the number of known elements up to 102. On the basis of what is already known of these elements, scientists predict that elements 103, 104 and 105 will soon be found. After that, they may discover another series of elements and the number will then climb even higher. The fact is, we do not know the exact number of different elements in the universe,

Though our world makes use of 92 different elements, some of them are abundant and some are very scarce. Oxygen makes up the bulk of the world's water, much of the air and almost half of the rocks of the earth's crust. Platinum is a scarce and precious element. Gallium is a very rare element found only in traces in certain zinc ores.

Each element, of course, is made of atoms all of one kind. The oxygen atom has eight protons in its nucleus, each bearing a single charge of positive electricity. Platinum has 78 protons and gallium has 31. Each element has an atomic number, depending upon the number of protons in the nucleus of its atom. The atomic number of oxygen is 8. Platinum has the atomic number 78 and gallium 31. In our everyday world, the atomic numbers run from 1, which is hydrogen,all the way up to 92, which is uranium.

The elements were not, however, discovered in this neat order from 1 to 92. Scientists started to arrange them in order after about 50 of them were discovered.

Almost 100 years ago, the Russian chemist Dimitri Mendeleev arranged the lists in the lines and columns which we call the Periodic Table. He saw family relationships between certain atoms and predicted that more would be discovered to fill certain gaps in the chart.

A whole new series of atoms was discovered with  radioactivity and the list of known elements reached 92. The development of nuclear fission and nuclear fusion revealed a series of atoms heavier than uranium. Element 93 was found in 1940 and named neptunium in honor of the planet Neptune. Plutonium, element 94, was found in the same year and named for Pluto.

In 1944, elements 95 and 96 were found. They were named americium, for the Americas and curium for the French scientists Marie and Pierre Curie. Berklium, atomic number 97, was found in 1949 and named for Berkeley, Calif. Californium, atomic number 98, was found in 1950 and. einsteinium, element 99, was found in 1952.

Element 100 was found in 1953 and named fermium in honor of the Italian scientist Enrico Fermi. Element 101, found in 1955, was named mendelevium, in honor of Mendeleev, Element 102 has been found, but the discovery is not yet verified. It has been tentatively named nobelium, in honor of Alfred Nobel who invented dynamite. Maybe in the next two years or ten years we will have found elements up to 105.