And now we're done with our lesson. Does anyone have any questions?
Could you give us a brief history on the periodic table?
So you see... in 1869, a chemist named Dimitri Mendeleev began the development of the periodic table. He arranged all elements based on their atomic mass, and left spaces for more undiscovered elements.
Over time, more discoveries were made; like of radioactivity and noble gases...
Sir William Ramsay
Then came the discoveries of the electrons, the nucleus, neutrons, and isotopes...
...And all of that led us to the periodic table that we use now!