Periodic Table of Elements

The periodic table is the most important reference a chemist has because it puts all the known elements into a meaningful pattern. Elements are arranged left to right and top to bottom in order of increasing atomic number. This order generally goes with increasing atomic mass.

Click on an element for more information(you will be leaving this site and going to the Los Alamos National Laboratory site):

The different rows of elements are called periods. The period number of an element signifies the highest energy level an electron in that element occupies (in the unexcited state). The number of elements in a period increases as one moves down the periodic table because as the energy level of the atom increases, the number of energy sub-levels per energy level increases.

In 1869, the Russian chemist Mendeleev noted that the repeating patterns of behavior could be arranged in a sequence of elements. This led to the first "Periodic Table" of the elements.

Scientists and students who are familiar with the periodic table use the position in the table to extract information about individual elements.

Chemistry in a Nutshell

For a list of the element names and symbols in alphabetical order.