“The Dependence Between the Properties of the Atomic Weights of the Elements.”
This is from the seminal publication of 1869, in which Dmitri Mendeleev first proposed THE predecessor to our periodic table’s organization.

Here is my favorite illustration of this series.

As you see, this chart is beginning to resemble our current periodic chart. The color and font variations are merely MY stylistic changes to remind us of the importance of the row and column groupings. Mendeleev, however, did more than just classify and group elements; his table allowed him to see such strong patterning of physical and chemical properties, that he was bold enough to call into question certain elements’ accepted atomic weights. Their lack of correspondence to the periodicity shown in the table gave the weight to his argument, and, with further investigation, he was proven correct. Not only did his insightful groupings correct atomic weights of Beryllium, Indium, Gold and Platinum, for example, but, it also allowed him to predict the existence of several unknown elements and their behavioral characteristics as governed by his chart.

IT SHOULD BE NOTED, that in 1864, 5 years prior to the publication of Mendeleev’s paper, that a Chemist name Julius Lothar Meyer had come to very similar conclusions about the periodic nature of elements. However, it wasn’t until 1870, a year after, that he formally published his version of the periodic chart! Who was truly the first frankly comes down to a matter of the publication race, a reality of the science world, even back then!

After de Chancourtois’ little known elemental organizational proposal, a chemist named John Newlands was expanding upon Dobreiner’s Law of Triad to a Law of Octaves, or 8-repeating sequences. He thus grouped them in a manner similar to the grid you see here (I couldn't find one figure to confirm what the original 56-element grid might have been). However, variation in the versions among the 5-6 references I came across included elements like Di, Ro, G, Gl and Ds....none of which exist today. Perhaps they were placeholders for undiscovered/unnamed elements? Possibly.

The key concept to take away here is that Newlands began to see similarities in physical properties having atomic weights close in range that came with groups of 8. So, the rows show the groupings based on relatively close atomic weights (designated by color). But, he also noted similarities in reactive, or chemical properties. So for these elements, he stacked these elements to form columns (designated by font), to denote that the element forms a second grouping, aside from the rows which assigned it to a first grouping.

Each element is now categorized in 2 ways: a row, or Periodic, grouping, and a column, or Group, grouping. Herein lies the foundation of the Periodic Table!

Did you guess that as more elements were discovered, that they would continue to fit Johann Dobereiner's Law of Triad pattern? That would've been the most logical guess, however, this is the 1800's, and we're dealing with science to boot, where thinking outside the box can strike gold!

So with that, take a look at this striking image circa 1862...what do you see? I hope you see a cylinder on the left-hand side that corresponds to the right-hand side, because that right-side image is the left-side cylinder that has been flattened out, or, unrolled. Alexandre-Emile Béguyer de Chancourtois was THE FIRST scientist to organize the elements known at the time by atomic weight or mass, based around the element Oxygen. He discovered this linear pattern between the known elements and their atomic mass, that could then predict where elements yet to be discovered would fall. For instance, on the flattened cylinder image, you see a gap between Beryllium (Be) and Carbon (C). Well, we know that gap is for Boron (B)! He preceded Mendeleev, who is known as the “Father” of the Periodic table, by 7 whole years.

So why are we NOT taught about him? Because apparently his publication that included this organizational graph was more about the geological properties of the elements, rather than the organization of them. He didn’t even publish this graph with the article. Chemists did acknowledge his very important contribution later, but Mendeleev is credited for many reasons, one of which was that his publication focusing on this periodic nature of the elements CAME FIRST.

Moral: It's all about timing.

At last, I’m ready to unleash the history of the development of the periodic chart!

Picture it: the year is 1829, and a scientist named Johann Dobereiner begins to notice some interesting patterns occurring within elements grouped in threes. For instance, the atomic weight of the element Strontium falls neatly in between Calcium and Barium:
Ca (AW=40) + Ba (AW 137) = 177 divided by 2 = 88 = Strontium's Atomic Weight!

He recognized these patterns in other triad sets, and this is how the race to organize the elements as they were discovered began. By identifying patterns found in their physical and chemical properties, scientists were able to predict that those elements would then have similar behavioral properties. And to make sense of these similarities, scientists then began arranging elements accordingly.

Next, you likely won’t guess in which direction elemental organization went. HINT: Do NOT (yet) look to the current periodic table for a hint!

In between my long series of posts on a certain topic, I like to sprinkle in something else that has caught my attention in the news. On one occasion it was about a local politician who was diagnosed with Non-Hodgkin Lymphoma, a type of cancer that originates in white blood cells. The cells themselves become abnormal and start to rapidly divide into tumors within the lymph nodes of our body. The resulting tumors have the potential to release abnormal white blood cells into the bloodstream, as white blood cells are a very important part of our immune system that search our bodies for foreign agents.

The main difference between Hodgkins and Non-Hodgkins lymphoma is that in Hodgkins, a very special cell called the Reed-Sternberg cell, is present. If this cell is not present, then it is classified as Non-Hodgkins, where only abnormal B-cells are present.
Staging is based upon extent of node involvement: how many AND where the affected nodes are, and how far from the point-of-origin node. Also, the presence of other tumors and where they are with respect to the original tumor is a factor.

Because staging of this cancer is dependent upon numerous factors, there are a myriad of treatment options. If the cancer is slow-growing, a wait and see approach might be adopted. Radiation, Chemotherapy, stem cell transplant, and other therapies targeted specifically to the abnormal B-cells are also viable treatments.

We end this odyssey with the O2, or oxygen molecule. This compound is made of two identical molecules that, like NaCl, come together to complete its outermost electron shell's octet rule, but accomplishes this in a very different way.

With NaCl, because Cl’s proton influence is stronger than that of Na, and that Cl has an almost-full outermost shell, Cl easily rips away Na’s singular outermost shell electron. In O2, each atom exerts the same proton strength. Furthermore, each one's outermost shell is nearly complete, with each possessing 6 of the 8 electrons needed. SO, what’s an oxygen atom to do?

SHARE. Each oxygen atom shares two of its p electrons with the other. So, NOW if you count the 2s and 2p electrons for each atom, you get 2-2s plus 6-2p electrons=8=OCTET achieved. 2 additional electrons from one oxygen atom have been shared with its partner oxygen atom. Likewise, the partner oxygen atom benefits from the sharing of two p-electrons from the first oxygen atom.

So, can anyone guess what charge each oxygen atom holds in a covalent bond?

Each oxygen atom holds no charge, or is neutral! Is this the case for all covalently bonded molecules? Certainly not, if each atom is a different atom. This means each atom will have a different number of protons, which can actually pull shared electrons closer to it, due its greater positive force of the aggregate protons! Then, the molecule will have dipole moments.