Who invented the Periodic table? And why Periodic tables are useful?

It also helps them understand how life works. It even helps them predict how new materials will behave. In 1869, Dmitri Mendeleev, a Russian chemist, proposed the periodic law and his first periodic table. He published this periodic table two years later in a textbook, The Principles of Chemistry.

Explanation:

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.