The periodic table, as we know it today, is an array of
arranged in order of increasing atomic
number. When the elements are arranged in order of increasing atomic number,
the physical and chemical properties of the elements vary periodically
at regular intervals. This relationship is known as the periodic
Click on the
and find periodic table icon, .
Click and view the periodic table as we know it today. Click on a few of the
elements on the periodic table and find out the element's name, its atomic
number and its atomic mass. You'll be using the periodic table quite often
throughout the course.
There are seven periods
of elements in the periodic table.
Each period has a variation in physical and chemical properties. It starts with
reactive metals on the left side and ends with the nonreactive noble gas on
the right side.
The number of the period gives the number of the outermost
principal energy level that the valence electron(s) occupies. This is best
illustrated by reviewing the arrangement of electrons in principal energy
levels and the Bohr diagrams.