Tag Archives: periodic table

These researchers want to rearrange the periodic table, and it looks trippy

Organizing chemical elements in a system that makes sense is not an easy feat. We take the periodic table (the bane of many a highschool student) for granted today, but when it was first invented, it was truly groundbreaking. Not only did Russian chemist Dmitri Mendeleev find a way to arrange the elements by their properties, but he even predicted the properties of then-undiscovered elements.

When Mendeleev first published his table in 1869, there were many gaps in it — after all, evidence for the existence of atoms had only recently emerged. So in addition to providing structure to the emerging science of chemistry, the table also helped predict new elements.

In a recent paper, researchers propose a novel way to arrange chemical elements, in a way that would also facilitate the discovery of new materials during our times.

Snippet from Mendeleev’s periodic table.Image credits: International Council of Science.

Researchers love arranging and sorting things in an orderly fashion. But in chemistry, this fashion was hard to find. For instance, noble gases (Helium, Neon, Argon, Krypton, Xenon, Radon), have different masses but they’re all noble gasses: odorless, colorless gases that don’t like to react with the ‘commoners’ of the periodic table. So Mendeleev arranged the noble gases one under another to mark this as a vertical similarity.

There are also horizontal similarities. Horizontally, elements are arranged by the number of protons in the nucleus. Between some groups, vertical similarities are more powerful, while other times, horizontal similarities describe the group. That’s why generally, the periodic table is also colored to mark distinctive groups.

It can all a bit confusing, but if you’re trying to arrange all the elements in the known universe, things are bound to get complex.

A new atomic table from Russia

Now, in a new study, researchers thought ‘what if we take this one step further’. One hundred and fifty years after Mendeleev, researchers Zahed Allahyari and Artem Oganov from the Skolkovo Institute of Science and Technology in Moscow built on earlier work to rearrange the periodic table. Instead of using the number of protons, they use two other properties: the atomic radius and a property called electronegativity, which measures the tendency of an atom to attract another atom and share a pair of electrons.

If you use these two properties and merge them together into just one, you get what’s called a Mendeleev Number (or MN). If you then order elements by their MN, you unsurprisingly end up with neighboring chemical elements having a similar MN. But if you take things further and construct the same list for two-element compounds (compounds consisting of two elements), you end up with something like this:

Image credits: Allahyari et al., Journal of Physical Chemistry, 2020.

If you have no idea what this means — don’t worry. The table isn’t aimed at chemistry hobbyists or students, but rather at specialized chemists and material science. Just like how Mendeleev’s table predicted the properties of elements, this trippy table predicts the materials’ properties. Properties such as hardness or magnetization are what’s represented here, and that’s what may be useful for material scientists to create new materials.

This could come in handy, for instance, if you’re looking for a substitute for one material (which may be expensive or scarce). You’d just look for something with similar properties and see what may be more readily available or cheaper. You could find alternatives for the rare elements used in batteries or electronics, for instance.

Similar ideas have been debated in the past. For instance, one such table shows the abundance of various elements on Earth and how likely they are to become scarce in the near future.

A modified periodi table showing the relative abundance of elements. Image credits: European Chemical Society/Wikipedia/CC BY-SA.

Ultimately, this shows that tables aren’t just useful for memorizing and structuring things. Similar to how the periodic table paved the way for future discoveries, new tables such as these can help researchers understand and develop the new generation of materials.

Four new elements officially added to the periodic table

In January, four new elements were introduced to the periodic table, but they didn’t have a name. Now, they will be officially added to the periodic table, with proper names.

Adapted from IUPAC by C. Smith/Science

The new elements have the atomic number (Z) of 113, 115, 117 and 118 respectively. Teams of researchers from US, Russia, and Japan have decided that the elements will be called:

  • Nihonium with the symbol Nh, for the element with Z =113, named after Japan.
  • Moscovium with the symbol Mc, for the element with Z = 115, named after Moscow.
  • Tennessine with the symbol Ts, for the element with Z = 117, named after Tennessee.
  • Oganesson with the symbol Og, for the element with Z = 118, named after Yuri Oganessian, a nuclear physics professor at the Joint Institute for Nuclear Research.

“It is a pleasure to see that specific places and names (country, state, city, and scientist) related to the new elements is recognized in these four names. Although these choices may perhaps be viewed by some as slightly self-indulgent, the names are completely in accordance with IUPAC rules”, commented Jan Reedijk, who corresponded with the various laboratories and invited the discoverers to make proposals.

“In fact, I see it as thrilling to recognize that international collaborations were at the core of these discoveries and that these new names also make the discoveries somewhat tangible.”

These elements were synthesized artificially and are not found in nature. They’re only stable for extremely short periods of time, which is why we don’t know too much about them and we can’t really perform any chemical experiments with them.

But with these four additions, the last row of the periodic table is complete — but that’s not to say that we can’t add another! Researchers will likely start synthesizing new, different elements, but we’ll need to add another row for that — or rather, a new block. This is truly something exciting and groundbreaking which could open new doors in modern chemistry. But of course, we’ll have to wait for scientists to actually create new elements before we can know.

This is the coolest periodic table you’ll see on the internet

We all know what the periodic table is – a simple arrangement of all the chemical elements based on their atomic structure. But what if I asked you to tell me a bit about noble gases or transitional metals? What if I asked you what an iron atom looks like?

[LINK HERE]

period-table1

With that in mind, programmer Sarath Saleem created a really cool interactive visualization of the periodic table, where you can simply click on an element and see how an atom looks like, and also explore its electron shells. You can view it in 3D, turn it around and make the electrons spin or stop spinning.

table2

I’m really impressed, I just wished I found this when I was in highschool.

How Albert Einstein broke the Periodic Table

In a study published in the January 19, 2016 issue of the Journal of the American Chemical Society (JACS), scientists at Tsinghua University in China confirmed that something very unusual is happening inside extremely heavy atoms, causing them to deviate from their expect chemical behavior predicted by their place on the Periodic Table of Elements. Due to the velocity of electrons in these heavy elements getting so close to the speed of light, the effects of special relativity begin to kick-in, altering the chemical features observed.

The study shows that the behavior of the element Seaborgium (Sg) does not follow the same pattern as the other members of its group, which also contain Chromium (Cr), Molybdenum (Mo), and Tungsten (W). Where these other group members can form diatomic molecules such as Cr2, Mo2, or W2, using 6 chemical bonds, diatomic Sg2 forms using only 4 chemical bonds, going unexpectedly from a bond order of 6 to a bond order of only 4. This is not predicted by the periodic nature of the table, which itself arises from quantum mechanical considerations of electrons in energy shells around the nucleus. So what’s happening here? How does relativity throw off the periodic pattern seen in our beloved table of elements?

The Periodic Table of elements was initially conceived by Dmitri Mendeleev in the mid-19th century, well before many of the elements we know today had been discovered, and certainly before there was even an inkling of quantum mechanics and relativity lurking beyond the boundaries of classical physics. Mendeleev recognized that certain elements fell into groups with similar chemical features, and this established a periodic pattern to the elements as they went from light weight elements like hydrogen and helium, to progressively heavier ones. In fact, Mendeleev could predict the very specific properties and features of, as yet, undiscovered elements due to blank spaces in his unfinished table. Many of these predictions turned out to be correct when the elements filling the blank spots were finally discovered. See figure 1.

 

Mendeleev's 1871 version of the periodic table. Blank spaced were provided where predicted new elements would be found.

Figure 1.   Mendeleev’s 1871 version of the periodic table. Blank spaced were provided where predicted new elements would be found.

 

Once quantum theory was developed in the early 20th century, the explanation for the periodic behavior of the table became apparent. The electrons in the atom are arranged in orbital shells around the nucleus. There are several different orbital types, again based on predictions from quantum mechanics, and each type of orbital can hold only a specified number of electrons before the next orbital has to be used. As you go from top to bottom in the Periodic Table, you use orbitals of progressively higher energy levels. Periodic behavior arrises because, although the energy levels keep getting higher, the number of electrons in each orbital type are the same for each group, going from top to bottom. See figure 2.

 

Figure 2. Group 1 as an example of a group in the Periodic Table. As the group goes from top to bottom the energy levels get higher and the elements get heavier.

Figure 2.   Group 1 as an example of a group in the Periodic Table. As the group goes from top to bottom the energy levels get higher and the elements get heavier.

 

The other great area of physics developed in the early 20th century was relativity, which didn’t seem to have much importance on the scale of the very small. Albert Einstein published his ground breaking paper on Special Relativity (SR) in 1905, which described the effects on an object moving close to the speed of light. In 1915 he developed the General Theory of Relativity (GTR), describing the effects due to a massive gravitational field. It is SR that becomes an important consideration in the very heavy elements due their electrons reaching velocities at a significant percentage of the speed of light.

Einstein showed that as the velocity of an object approaches the speed of light its mass increases. This effect is too small to be noticeable at everyday speeds, but becomes pronounced near light speed. It can also be shown that the velocity of an electron in orbit around an atom, is directly proportional to the atomic number of the atom. In other words, the heavier the atom, the faster its outer electrons are moving. For the element hydrogen, with atomic number 1, the electron is calculated to be moving at 1/137 the speed of light, or 0.73% of light speed. For the element gold (Au) with atomic number 79, the electrons are moving at 79/137 the speed of light, or 58% of light speed, and for Seaborgium (Sg) with atomic number 106, the electron is going at an impressive 77% of light speed. At these speeds the crazy effects of special relativity kick-in making the electron mass significantly heavier than it is at rest. For gold this makes the electron 1.22 times more massive than at rest, and for Seaborgium the electron’s mass comes out to be 1.57 times the electron rest mass. This, in turn, has an effect on the radius of the electron’s orbit, squeezing it down closer to the nucleus.

Some relativistic effects have already been known for certain heavy elements. The color of gold, for instance, arises due to the effects of relativity acting on it’s outer electrons, altering the energy spacing between two of it’s orbitals where visible light is being absorbed, and giving gold it’s characteristic color. If not for these relativistic effects, gold would be predicted to appear whitish.

For the elements in Group 6 of the Periodic Table (Cr, Mo, and W) (see Figure 3.) that were studied in the JACS article, they each have five d-orbitals and one s-orbital capable of forming bonds with another atom. Sg breaks the periodic pattern because it’s highest energy s-orbital is so stabilized by the effects of it’s relativistically moving electron, it doesn’t contribute to bonding. Due to the intricacies inherent in molecular orbital theory, this drops the number of bonding orbitals from 6 in Cr, Mo, and W, to only 4 in Sg (even though Sg is a group 6 member). It also means that the bond between Sg and Sg in the Sg2 molecule is 0.3 angstroms longer than expected, even though the Sg radius is only 0.06 angstroms bigger than W. If relativity didn’t have an effect, then the Sg2 molecule would be joined together by 6 orbital bonds, like any respectable Group 6 element should be! The same effect was also found in the Group 7 elements, with Hassium (Hs) showing the drop in bond order due to relativistic effects, just as Sg.

 

Figure 3. A modern version of the Periodic Table of Elements. Notice the Group 6 elements Cr, Mo, W, and Sg.

Figure 3.   A modern version of the Periodic Table of Elements. Notice the Group 6 elements Cr, Mo, W, and Sg.

 

The periodic table of elements is an impressive scientific achievement, who’s periodicity reveals an underlying order in nature. While this periodicity works remarkably well, the few exceptions to the rule also uncover important principles at work. Einstein’s theory of relativity breaks the periodic table in some interesting and unexpected ways. It’s the very heavy elements on the chart that don’t show good “table” manners, thanks to Einstein.

 

Journal Reference and other reading:
1. Relativistic Effects Break Periodicity in Group 6 Diatomic Molecules Yi-Lei Wang, Han-Shi Hu*, Wan-Lu Li, Fan Wei, and Jun Li*
Department of Chemistry & Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Tsinghua University, Beijing 100084, China  J. Am. Chem. Soc., 2016, 138 (4), pp 1126–1129 DOI: 10.1021/jacs.5b11793 Publication Date (Web): January 19, 2016

2. Relativistic effects in structural chemistry Pekka Pyykko Chem. Rev., 1988, 88 (3), pp 563–594 DOI: 10.1021/cr00085a006 Publication Date: May 1988

3. Why is mercury liquid? Or, why do relativistic effects not get into chemistry textbooks? Lars J. Norrby J. Chem. Educ., 1991, 68 (2), p 110
DOI: 10.1021/ed068p110 Publication Date: February 1991

Nucleosynthesis_Cmglee_1280

Where elements come from: this periodic table explains it all

Nucleosynthesis_Cmglee_1280

Image Credit: Cmglee (Own work) CC BY-SA 3.0 or GFDL, via Wikimedia Commons

You may have heard about how we’re all made of star dust. That’s quite accurate, considering most elements that makeup the human body including carbon, oxygen or phosphorus were made by nuclear fusion inside the core of stars. Hydrogen, however, was made during the Big Bang, as well as helium along with traces of  lithium and beryllium. Eventually, as the Universe cooled and expanded, cosmic dust and gases accreted and pressed by gravity formed stars.

For most of their time, stars are busying fusing hydrogen into helium. When they run out of hydrogen, stars begin to die. It will expand into a red giant star producing carbon atoms by fusing helium atoms. Those stars that are more massive have even more nuclear reactions and form elements ranging from oxygen to iron.

Nucleogenesis reactions

  •  3 helium atoms fusing to give a carbon atom: 3 @ 4He → 12C
  •  carbon atom + helium atom fusing to give an oxygen atom: 12C + 4He → 16O
  •  oxygen atom + helium atom fusing to give a neon atom: 16O + 4He → 20Ne
  •  neon atom + helium atom fusing to give a magnesium atom: 20Ne + 4He → 24Mg

The last stellar evolutionary stages of a massive star’s life is marked with a boom: a supernova. As the star explodes it releases a massive amount of energy and neutrons, forming elements heavier than iron: uranium, gold etc.

[YOU SHOULD DEFINITELY CHECK OUT] 112 Elements from the Period Table Illustrated as Characters

So,  4 elements were made during the Big Bang, while 86 are made by stars. The rest of 28 out of 118 are thought to be man-made. That is, these have only been detected in labs in conditions staged by humans. Of course, these must form in nature as well, but only for a couple of moments before decaying into something else.

[via NASA’s APOD]

The periodic table welcomes its new member: Copernicium

Copernicium is now officialy the newest and heaviest element in the periodic table, with an atomic number of 112 (which means that it has 112 protons in its nucleus); it’s also 277 times heavier than hydrogen.

copernicium

Named after astronomer Nicolaus Copernicus, it follows a long tradition of naming elements after famous scientists; some of the latest in this line include Einsteinium (for Albert Einstein), Fermium (for nuclear physicist Enrico Fermi), and Curium (after Marie Curie and her husband Pierre).

NOTE: Today we implement what we’ve called ‘shorties’ – just short news, without going into any details, but definitely interesting and worth noting. Any feedback is well appreciated

New chemical element in the Periodic Table!

chemimage1

Were you one of those students who used to complain about all those chemical elements you had to study at school? Well, I guess this particular piece of news will not exactly make you celebrate.

It seems that chemistry has yet a lot more to offer as the element 112 has just been recognised by the International Union of Pure and Applied Chemistry (IUPAC). Now what the scientists at the Centre for Heavy Ion Research in Darmstadt have to do it’s find it a name

The suggestion is to be submitted and in about 6 months the element will finally be “baptised”.

The new discovery has made all the scientists from Germany, Finland, Russia and Slovakia who were involved in the research extremely delighted even though it’s not the first time a chemical element has been discovered by GSI;  the elements: Bohrium(107), Hassium(108), Meitnerium(109), Darmstadtium(110) and Roentgenium(111) are also their discoveries.

The new element has already set a new record as it is the heaviest one in the periodic table, being 277 times heavier than hydrogen.

The story of the new element began in 1996 when the scientists created the first atom of the element by using an accelerator. Another atom was produced in 2002 and then more were created.

In order to give birth to the new element zinc ions were “fired” onto a lead target by using the accelerator. The resulted nuclear fusion gave birth to the nucleus of the new element 112, this number being the sum of the atomic numbers of lead (82) and zinc(30). The atomic number represents the number of protons in the nucleus of an element; neutrons are not taken into cosideration as they do not influence the classification of the elements.

So there it is: a new chemical element has been welcome by the scientific community but don’t worry: it will take some time before it gets into the Chemistry books!

source:GSI Helmholtzzentrum für Schwerionenforschung.