Happy International Year of the Periodic Table! 150 years ago, Dmitry Mendeleev published his periodic table, giving order and meaning to the elements that build our world. We'll be celebrating this and other chemistry achievements all year. #IYPT2019 . "When the elements are arranged in vertical columns according to increasing atomic weight, so that the horizontal lines contain analogous elements again according to increasing atomic weight, an arrangement results from which several general conclusions may be drawn." —Dmitry Mendeleev, 1869 . . . . . . . . . #periodictable #internationalyearoftheperiodictable #yearoftheperiodictable #chemistry #science #chem #scienceclass #sciencegeek #scienceiscool #stem #elements #organization #electron #neutron #table #chart #atomicnumbers #atom #chemical #group #understand #metals #history #sciencehistory