Facts Periodic Table..

• Periodic table contains 7 horizontal rows called periods and 18 vertical columns called groups.
• Father of periodic table is Mendeleev.  
• Dmitri Mendeleev is generally credited with the publication, in 1869, of the first widely recognized periodic table.
• Mendeleev’s periodic table is based on atomic weight.
• Modern periodic table is based on atomic number elements.
• A British physicist named Henry Moseley developed the first periodic table based on atomic number.
• Elements of group 1 are called Alkali metals. Elements of group 2 are called Alkaline earth metals. Elements of group 17 are called Halogens.
• There are 116 elements known today out by which 90 naturally existing.
• First period contains only 2 elements, this is the shortest period.
• Elements of group zero show little reactivity and are termed noble gas.
• Element of atomic number 87 to 105 are radioactive elements.
• The first man mad element is Technetium (atomic no 43)
• Promethium is also a manmade element (atomic no 63)
• Element from atomic number 93 onwards do not occur in nature. So they are called synthetic or transuranic elements.
• Manmade elements are known as transuranic.
• Element from atomic number 58 to 71 are lanthanides or rare earths.
• Elements from atomic number 90 to 103 are termed as actinides.  
• Noble gas is listed in group 18 of modern periodic table.