Atomic Basics :

 The Periodic Table

Tool: Interactive Periodic Table
Take a look at a Periodic Table. If you don't have one already, you can print the table available here.

The table is read just like any other written piece of information, from left to right and top to bottom. The first and simplest element is hydrogen, found in the extreme upper left corner of the table. It has an atomic number of 1. This means there is only one proton in the nucleus of any hydrogen atom. The next element in the table is located in the extreme right top corner of the table. This is helium. Helium has an atomic number of 2. There are two protons located in the nucleus of each and every helium atom or ion. In following the pattern described, you must look down one row and to the left side of the table to find the next element -- lithium. This is the same as looking back to the left side of the page and down one line to read this complete sentence.

By definition, an atom of any element has no overall charge. So as you add the protons one at a time, you are also forced to add electrons one at a time to balance the electrical charge of the atom. There are some very strict rules as to how and where these electrons have to be added to the atoms. We will be going over the rules for electron placement in the next chapter, It's Elementary.

Think you've mastered the basics? Test your knowledge with the "Name That Atom" interactive activity!