I believe it to be by the number of protons in the nucleus.
five hundred dollars
The elements in the periodic table are arranged by their atomic number, which represents the number of protons in the nucleus of an atom. This arrangement helps to group elements with similar properties together in columns known as groups or families.
I'd return that tablet.
Phosphorus
meercury , lead
Copper
J
Francium
Dmitri Mendeleev in 1869
2
7 periods.
I think it was Mendaleev's periodic table.