Karen Iandell, age 12, of Houston, Texas, for her question:

How do the elements get their atomic numbers?

Each of the basic chemical element has its own indisputable signature. It is a certain atomic number, a whole number that sets it apart from all other elements and decides its place on the periodic table Actually it states the exact number of protons in the nucleus of every atom of a certain element. This is the basic key to every atom in creation.

As we know, the central core of the atom is a tight fisted nucleus of assorted par¬ticles and dynamic energies. The key nuclear particles are protons and all protons are alike. And, of course, each atom has its own number of protons. It belongs to a certain chemical element and all other atoms of this element have the.same number of protons. Hence, each of the known 104 chemical elements gets its atomic number from the number of protons in the nuclei of all its atoms.

For example, the smallest of all atoms is hydrogen and the nucleus of every hydrogen atom has one, and only one, proton particle. Naturally, the element hydrogen is entitled to atomic number one. This number cann t belong to any other element. In the dynamic reaction called nuclear fusion, two hyd ogen atoms combine to form a nucleus which has two protons. This disqualifies them as hydrogen atoms. The new atom is one of helium. naturally the two nuclear protons quality the element helium as atomic number two.

Atomic number three belongs to the element lithium, because each and every lithium atom has a nucleus that contains three protons. If a lithium atom loses a proton, it becomes an atom of helium. If by chance it gains an extra proton it becomes an atom of beryllium the one and only element tat qualifies for atomic number four.

Every atom of iron has 26 protons And every atom of cobalt has 27. If you guessed that these two elements are atomic number 26 and 27, you have mastered the first basic key in nuclear physics. The known elem nts are charted on the periodic table, with their atomic numbers. Fewer than 100 of the known elements are used to build all the natural solids, liquids and gases of the earth.

An atom, of course, is built from assorted particles, only one of which is the proton. They come in larger and smaller sizes, 1harged with various energies. The proton's energy is one charge of positive electricity   equal and opposite to the negative charge of one electron particle. These opposite charges attract each other. Hence, the atomic number of an atom entitles it to an equal number of both protons and electrons.

A normal atom is electrically neutral because it has an equal number of positive protons and negative electrons. But electrons swarm around outside the nucleus and often stray from home. When a nucleus loses or gains an electron, its electrical balance is upset and it becomes a charged ion. However, this does not change its atomic number be¬cause the number of protons in its nucleus remains the same. But in radioactivity, the nucleus is remodeled. And when it gains or loses a proton it becomes a different ele¬ment with a different atomic number.