Question

Mendeleev's periodic table was organized by?

Answer 1

increasing atomic mass

Answer 2

mendeleev, a russian chemist, I think. Increasing atomic NUMBER. A step of 1 in atomic number (no of electrons or protons in an atom) changes the atom by one element. H = 1, He = 2, Li = 3 and so on. You can have atoms with the same numbers of electrons, but DIFFERENT NUMBERS OF NEUTRONS, and therefore DIFFERENT ATOMIC MASSES. They are called ISOTOPES. Uranium 235 and uranium 238; carbon - 12, and carbon - 14 are useful examples of isotopes. Carbon's atomic NUMBER is 6.
Bon voyage and bon chance
http://perendis.webs.com

Answer 3

ps to last post. I'm assuming that M's periodic table is the "same" as the ones used in various textbooks and schools etc and data books, such as one that I have. If that's NOT the case, then scrub previous post. If it is the case then that's ok.

Answer 4

It was organized by John Newlands

Answer 5

John Newlands was a forerunner of Mendeleev and contributed to the ideas but not the detail.

Mendeleev arranged elements by their atomic mass (not by atomic number)

We now know that Atomic number is the 'correct' order (i.e. number of protons in the nucleus) however Mendeleev noticed the repeating nature of the groups of elements and arranged them in the correct columns.

Answer 6

@MrNood If M went by atomic mass, then who decided to go by atomic number ? Wasn't it M, again. And then make it a table, rather than a list, and as a table, it comes out with that "odd" shape ... ? For instance, ultra reactives on the left, and noble/inerts on the extreme right, H by itself, and a hole, the base of which is the transition element/metals. When all said and done, it's a useful guide for a mouse in a maze.
http://perendis.webs.com

Answer 7

@osprey

This from wikipedia

Later in 1913, Henry Moseley determined experimental values of the nuclear charge or atomic number of each element, and showed that Mendeleev's ordering actually corresponds to the order of increasing atomic number

Answer 8

@MrNood Ty for the "wiki leak". Shows you how bad my chemistry is, this does. Did Moseley get a Nobel prize or something ? So, that thing I look at was actually "designed" by whom ?

Answer 9

I think the wiki link gives a general story of the evolution of the table.
The structure was only understood once the 'electron shell' was understood.

Incidentally - there is an interesting 'spiral' version of the table that shows the transitions, the actinide and the lanthanides more clearly.

Also an arrangement by 'electron shell fill order' which also explains the actinides and lanthanides