Christine Hickey, age 13; of Pittsburgh, For for her question:

What is the Periodic Table?

This neat chart of squares arranged in rows and columns is the ABC of chemistry and no harder to fathom than the alphabet was when you were

six  In large print, it fits nicely onto a double page, At first glance,

Table the lonely letters and the crisp figures in the squares of the Periodic look very bewildering  But every young citizen of the Age of Science is curious to learn the tricks of the puzzle, For it tells the nature of cash of the basic chemical elements  It lays bare the secrets of how certain elements can form compounds ‑ how the gas hydrogen can combine with the different gas oxygen to form liquid water, how the metal sodium can combine with the poisonous gas chlorine to form table salt 

With a few exceptions, each of the basic elements is allotted one square on the Periodic Table along with its atomic number and its atomic weight  The shorthand symbol of the element is in the middle of the square  H is for hydrogen, He is for helium  Na is for natrium which is the Latin name for sodium  You can soon learn these symbols and the reasons for them 

The atomic number is a whole number, usually at the top of the square  It gives the number of proton particles in the atoms from which the element is made  In the core or nucleus of an atom there are a definite number of protons charged with positive electricity and around the nucleus there are an equal number of swarming electrons charged with negative electricity 

Every atom of the element carbon has six protons and normally six electrons orbiting the nucleus  The atomic number for carbon, symbol C, is 6  The atomic number for helium, He, is 2 and every other‑element has a different atomic number all its own 

If you count across the rows or periods of the Periodic Tables you will find that the numbers run from left to right, from one to more than 100,

The other number in the square with each element is the atomic weight, the mass of all the particles in a normal atom of this element  All the atoms except common hydrogen contain neutrons in their nuclei  The neutrons are electrically neutral, but they add to the mass of the atom: The atomic number of carbon is 6, its mass number is a little more than 12  The atomic number of neon is 10, its mass number is a little more than 20 

The columns of squares, called gubugs, can tell us which elements resemble each other  The first two columns on the left are light metal elements  Then come groups of heavy metals and non‑metals  The last column is a group of inert gases  There is a sequence in the atomic numbers down each column which you can probably figure out for yourself  This sequence tells how a group of elements will react chemically with other elements to form compounds  There are enough of these fascinating ins and outs to fill whole books on chemistry and Andy promises to explain how some of them work in the near future  

For further Information go to: http://www.webelements.com/