The periodic table is an arrangement of the elements by increasing atomic number. Since the electrons add to energy levels in a regular pattern, elements with similar chemical properties tend to repeat themselves with a set period. This allows the table to be constructed such that elements that are most alike in chemical properties are in the same column.
The first view shows an abbreviated version
of the periodic table from the Las Alomos National Laboratory.
This second table charts the elements
by electronegativities. Dark blue: highest electronegativity, red, lowest.
Electronegativity is a measure of an atom's tendency to grab electrons
from other atoms. The electronegativities run from low electronegativity
in red to high electronegativity
in blue. Elements that are strongly
electronegative such as oxygen or fluorine strongly grag and hold electrons.
Important Elements This view of the periodic tabl, high-lights
the 26 elements that are important to living things. These include the big six:
Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus(CHNOPS).
The rest are generally considered trace elements. They are often very important
but needed in much smaller amounts.