The United Nations announced 2019 as the International Year of the Periodic Table of the Chemical Elements to highlight its first publication in 1869.  

• The periodic table as we know it today was first designed by the Russian scientist Dmitri Ivanovich Mendeleev.  
• This year marks the 150th anniversary of the first publication of the periodic table by Mendeleev.  
• Since its creation, the periodic table has been at the centre of a lot of vivid debates and is now considered as “one of the most important and influential achievements in modern science reflecting the essence not only of chemistry, but also of physics, biology and other disciplines.” 

• Mendeleev’s genius lies in the acknowledgement that at the time, not all the elements were known yet, so he left gaps in the table for undiscovered elements.  
• At that time, only 63 elements had been identified. Still the properties of five other elements (the gaps brilliantly added to complete the table) could already been determined using the table. 

Source: NCERT and Indian Express