Periodic Table of Elements
The periodic table of elements list all of the known elements. In
addtion, the chart lists useful information such as the atomic mass, the
number of electrons in each orbit, the elements state of matter,
the characteristics of the element, and the atomic symbol. The periodic
table was first developed by the Russian Scientis Dmitry Menedeleev in
1869. Mendeleev's table included all of the 63 elements known at that time.
Since the time of Mendeleev, sceintist have discovered 90 naturally
occruing elements. In addition, scientist have created 25
Definitions
atomic mass - the average mass of an atom. Atomic mass is
measured in amu. or atomic mass units. The proton and neutron are so much
larger in mass than theelectron that the atomic mass is roughly equal to
the mass of the protons and neutrons of an atom. The number of neutrons
present in an atom can be measured by subtracting the number of protons
from the atomic mass. This calculation is helpful when determing the isotope
of an element.
atomic number - the total number of protons of an element
atomic symbol - the sequence of Capital and Lowercase
letters that represent an element on the Periodic Table.
Reading the Periodic Table
The Periodic Table of Elements
for an interactive version of the periodic table visit the Los
Alamos Laboratory web site at http://pearl1.lanl.gov/periodic/default.htm.
Some of the above information has been gathered from the Los
Alamos Laboratory Web Site.
page created by Paula Jarrett Nasta
last updated 4/27/02