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  2. Pi bond - Wikipedia

    en.wikipedia.org/wiki/Pi_bond

    A typical triple bond, for example in acetylene (HC≡CH), consists of one sigma bond and two pi bonds in two mutually perpendicular planes containing the bond axis. Two pi bonds are the maximum that can exist between a given pair of atoms. Quadruple bonds are extremely rare and can be formed only between transition metal atoms, and consist of ...

  3. Periodic table - Wikipedia

    en.wikipedia.org/wiki/Periodic_table

    The periodic table and law are now a central and indispensable part of modern chemistry. The periodic table continues to evolve with the progress of science. In nature, only elements up to atomic number 94 exist; [a] to go further, it was necessary to synthesize new elements in the laboratory.

  4. Ball-and-stick model - Wikipedia

    en.wikipedia.org/wiki/Ball-and-stick_model

    Double and triple bonds are usually represented by two or three curved rods, respectively, or alternately by correctly positioned sticks for the sigma and pi bonds. In a good model, the angles between the rods should be the same as the angles between the bonds , and the distances between the centers of the spheres should be proportional to the ...

  5. List of chemistry mnemonics - Wikipedia

    en.wikipedia.org/wiki/List_of_chemistry_mnemonics

    A mnemonic is a memory aid used to improve long-term memory and make the process of consolidation easier. Many chemistry aspects, rules, names of compounds, sequences of elements, their reactivity, etc., can be easily and efficiently memorized with the help of mnemonics.

  6. Tennessine - Wikipedia

    en.wikipedia.org/wiki/Tennessine

    Tennessine is a synthetic chemical element; it has symbol Ts and atomic number 117. It has the second-highest atomic number and joint-highest atomic mass of all known elements and is the penultimate element of the 7th period of the periodic table.

  7. Chemical bond - Wikipedia

    en.wikipedia.org/wiki/Chemical_bond

    See sigma bonds and pi bonds for LCAO descriptions of such bonding. [22] Molecules that are formed primarily from non-polar covalent bonds are often immiscible in water or other polar solvents, but much more soluble in non-polar solvents such as hexane. A polar covalent bond is a covalent bond with a significant ionic character. This means that ...

  8. Pi-interaction - Wikipedia

    en.wikipedia.org/wiki/Pi-interaction

    In chemistry, π-effects or π-interactions are a type of non-covalent interaction that involves π systems.Just like in an electrostatic interaction where a region of negative charge interacts with a positive charge, the electron-rich π system can interact with a metal (cationic or neutral), an anion, another molecule and even another π system. [1]

  9. Cation–π interaction - Wikipedia

    en.wikipedia.org/wiki/Cation–π_interaction

    The following table shows a series of Gibbs free energy of binding between benzene and several cations in the gas phase. [ 2 ] [ 6 ] For a singly charged species, the gas-phase interaction energy correlates with the ionic radius , r i o n {\displaystyle r_{\mathrm {ion} }} (non-spherical ionic radii are approximate).