period of an element signifies the highest energy level
an electron in that element occupies in an unexcited
state. Generally, within a given period, the chemical
activity of metals increases with the group number ,
while the chemical activity of non-metals within a given
period decreases with the group number.
and the first Periodic Table
Mendeleev was born on February 7th 1834 in Tobolsk, a Town in Siberia.
In 1869 at the age of 35 the famous Russian Scientist perceived a
totally new classification Method "the periodic table", he
included all the 65 elements
known in his time by their atomic weights and chemical valency.