In 1843, Leopold Gmelin worked with the Dobereiner’s system and developed a table of 55 elements that contained many of the similar relationships later found in the modern periodic table. Then in 1857 ...

The modern periodic table is based closely on the ideas he used. Cal: And how is it ordered? Mrs Roberts: So, the elements are arranged in order of increasing atomic number. The horizontal rows ...

So how has the periodic table been put together? Mrs Roberts: Well, the modern periodic table shows us all of the elements arranged in rows, which are called periods. It has changed a lot over the ...

img src="https://img.jagranjosh.com/images/2024/May/3152024/periodic-table-of-elements-chemistry.jpg" width="1200" height="675" /> Periodic Table Chemistry: The ...