Manufacturing Bits: Sept. 11

Periodic table for molecules; upside down chemistry; chem art.


Periodic table for molecules
In what could propel the development of new materials, the Tokyo Institute of Technology has developed a periodic table for molecules.

If the proposed concept is developed and adopted, the table could one day be used for creating new materials. It also may predict new materials for future use.

This table is somewhat akin to the periodic table of elements, which is a display of the chemical elements that are arranged by atomic number. In fact, 2019 marks the 150th anniversary of the periodic table of elements. Recently, the United Nations proclaimed 2019 as the International Year of the Periodic Table of Chemical Elements. In 1869, Russian chemist Dmitri Mendeleev published the first periodic table.

The periodic table of elements serves as an invaluable tool for science. So why not one for molecules?

In the past, various researchers have considered the idea, but many of those concepts were limited.

Taking the idea to a new level, researchers from the Tokyo Institute of Technology have devised a periodic table for molecules with multiple types of symmetries.

The approach is based on the behavior of the valence electrons of atoms, which form molecular clusters. “When multiple atoms form a cluster with a symmetrical shape, their valence electrons tend to occupy specific molecular orbitals called as ‘super-atomic orbitals,’ in which they behave almost exactly as if they were the electrons of a huge atom,” according to the Tokyo Institute of Technology.

Using this concept, researchers have proposed the idea of “symmetry-adapted orbital (SAO) models.” The new molecular periodic table would be created for each SAO type. The molecules are classified based on four parameters: groups, periods, species, and families.

This table only serves as a starting point and can be further developed. “Modern synthesis techniques enable us to produce many innovative materials based on the SAO model, such as lightweight magnetic materials,” said Kimihisa Yamamoto, a professor at the Tokyo Institute of Technology. “Among the infinite combinations of constitutive elements, the proposed periodic table will be a significant contribution to the discovery of novel functional materials.”

Orbital patterns for different structural symmetries (Source: Tokyo Institute of Technology)

A periodic table for various types of tetrahedral molecules (Source: Tokyo Institute of Technology)

Upside down chemistry
The University of Nottingham, the University of Liverpool and the University of Manchester recently proposed an idea to make the periodic table of elements easier to understand.

The answer: Turn the table upside down.

Researchers believe that turning the table 180 degrees with the figures right side up makes more sense. It would read more like a graph, where the values increase from bottom to top. In other words, the lighter elements would be at the bottom. The heavy ones are on top.

“Think of the periodic table from the viewpoint of children looking for the first time at Mendeleev’s table hanging on the classroom wall. The teacher rarely mentions any of the elements that are typically closest to the children’s eye-level and talks mostly about those high up near the top of the table. The current layout also makes it harder to understand one of the key concepts underlying the structure of the periodic table, namely the order of the filling of electron shells. In Mendeleev’s table, these fill from the top to the bottom while most everyday objects like beakers, baths and waste bins fill from the bottom up,” said Martyn Poliakoff, a professor of chemistry at the University of Nottingham.

Chem art
Art. Lebedev Studio, a Moscow-based design company, has released a new periodic table that can be adapted for any task. The table can be arranged to handle over 100,000 permutations. You can create your own table for free.

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