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I am preparing a presentation on Lewis dot structures. The package bohr is really good to make diagrams that help in visualizing the ionic and covalent bond.

For the ionic bond I am quite happy with the results... but for the covalent bond, I would like to stress more the fact that electrons are being "shared" between atoms. I think the first image in this wikipedia article (https://en.wikipedia.org/wiki/Covalent_bond) is good enough.

This is my code, so far:

\documentclass{beamer}
\usepackage{chemmacros}
\usepackage{bohr}

\begin{document}
\begin{frame}{Enlace iónico}
  \centering
  Antes...\par
  \bohr{11}{Na} \quad\quad \bohr{17}{Cl}\par
  Después...\par
  \setbohr{atom-style={\footnotesize\sffamily\ch}}
  \bohr{10}{Na+} \bohr{18}{Cl-}
\end{frame}
\begin{frame}{Enlace covalente}
  \centering{}
  Antes...\par
  \bohr{1}{H} \quad\quad \bohr{1}{H}\par
  \vspace{1cm}
  Después...\par
  \bohr{1}{H} \bohr{1}{H}
\end{frame}
\end{document}

enter image description here enter image description here

The question is... can I change the position (in polar coordinates, from 0 to 180 degrees) of the electron in the second H atom? That way both electrons will be at the center (between both atoms).

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  • *Welcome on tex.stackexchange.com * Non answer: Bohr model is very interesting from an an historical point if view, but not very efficient for multi-electron atom, and becomes more or less silly when you go at molecular orbitals.
    – Jhor
    Commented Jul 17, 2023 at 3:09
  • If youvreally want to o that, you could take advantage of the symmetry of 'H', and use \reflectbox(package loaded with graphicx) for the left atom.
    – Jhor
    Commented Jul 17, 2023 at 3:15
  • Thanks a lot @Jhor. It works with reflectbox Nice trick. :) Commented Jul 17, 2023 at 17:42
  • The package uses TikZ to draw the images. So, I would guess that it should be possible to rotate the whole thing (except for the text) if this is what you want? Commented Jul 17, 2023 at 18:22

2 Answers 2

5

The package is based on TikZ, and it hence allows you to set whatever tikz options you want to the relevant parts of the diagram. The package offers the \setbohr command to set options for all following \bohr diagrams. If you only want to affect the next one, you need to make sure that the \setbohr command and the relevant \bohr command are scoped properly (I used \begingroup and \endgroup in this example, but maybe you don't need this, because the relevant diagram is already inside a scope).

To add options to the electrons and this way affect their shape or position, you can use \setbohr{electron-options-add={...}} and then use rotate=180 for a rotation by 180 degrees or xscale=-1 to flip the electrons from left to right:

\documentclass[border=10pt]{standalone} 
\usepackage{bohr}

\begin{document}
    \bohr{1}{H}

    \begingroup
        \setbohr{electron-options-add={rotate=180}}    
        \bohr{1}{H}
    \endgroup
\end{document}

enter image description here

\documentclass[border=10pt]{standalone} 
\usepackage{bohr}

\begin{document}
    \bohr{5}{B}

    \begingroup
        \setbohr{electron-options-add={rotate=180}}    
        \bohr{5}{B}
    \endgroup

    \begingroup
        \setbohr{electron-options-add={xscale=-1}}    
        \bohr{5}{B}
    \endgroup
\end{document}

enter image description here

0

Thanks to @Jhor for suggesting the reflectbox command from the graphicx package in the comments! The code is (only for the second frame):

\begin{frame}{Enlace covalente}
  \centering{}
  Antes...\par
  \bohr{1}{H} \quad\quad \bohr{1}{H}\par
  \vspace{1cm}
  Después...\par
  \bohr{1}{H} \reflectbox{\bohr{1}{H}}
\end{frame}

Plus... you have to load the graphicx package in the preamble of the document.

The result.. enter image description here

Still... it would be better to know if it is possible to change the electron manually (with the bohr package). So, this works, but as pointed out by @Jhor, it is due to symmetry.

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