Cfrgtkky

As english is not my primary language, I don't know how describe my problem the right way. But I have a picture of what I want to type.

This is how far I have made it:

documentclass[a4paper]{article}

usepackage{tikz-cd}

begin{document}

begin{tikzcd}

    Cr & 3downarrow arrow[rd] & 2Cr: & 6downarrow \

    C & 2uparrow arrow[ru]& 3C: & 6uparrow

end{tikzcd}

end{document}

Background: At my school we use this to show how to align(?) a redox-reaction.

If you would like to think of the reaction as an equation rather than a diagram, you can also use tikz marks to do that:

documentclass{article}

usepackage{amsmath, tikz}

usetikzlibrary{decorations.pathreplacing, calc}

newcommand{tikzmathnode}[2]{tikz[remember picture, baseline]{node[inner sep=1pt, outer sep=0pt, anchor=base, minimum height=1em] (#1) {$displaystyle #2$};}}

newcommand{redoxdraw}{

  begin{tikzpicture}[overlay, remember picture]

    draw[decoration = {brace, amplitude=.3em, raise=.1em}, decorate] (redox1.north east) -- (redox2.south east);

    draw[-to, out=0, in=180] ([xshift=.8em] redox1.east) to ([xshift=2.5em] redox2.east);

    draw[-to, out=0, in=180] ([xshift=.8em] redox2.east) to ([xshift=2.5em] redox1.east);

  end{tikzpicture}

}

newcommand{redoxfirst}[1]{tikzmathnode{redox1}{#1}qquad}

newcommand{redoxsecond}[1]{tikzmathnode{redox2}{#1}qquadredoxdraw}





begin{document}

begin{equation*}

  begin{array}{rrrr}

    Cr: & redoxfirst{3downarrow} & 2Cr: & 6downarrow\[.3em]

     C: & redoxsecond{2uparrow}   & 3C: & 6uparrow

  end{array}

end{equation*}

end{document}

You can of course play around with the spacing or hard-code less of the format. You could also make redoxfirst and redoxsecond take an optional argument to name the reaction, so as to allow multiple reactions in the same line.

Try with tikzmark:

documentclass[a4paper]{article}

usepackage{tikz}

usepackage{tikz-cd}

usetikzlibrary{decorations.pathreplacing}

usetikzlibrary{calc,tikzmark}



begin{document}

  begin{tikzcd}

      Cr: & 3downarrow  tikzmark{bracebegin} hspace{4pt} arrow[rd] & hspace{4pt} 2Cr: & 6downarrow \

      C: & 2uparrow  tikzmark{braceend} hspace{4pt} arrow[ru]   & hspace{4pt} 3C: & 6uparrow

  end{tikzcd}

  begin{tikzpicture}[overlay,remember picture]

  draw[decorate,decoration={brace}] ( $ (pic cs:bracebegin) +(0, 9pt)  $ ) -- ( $ (pic cs:braceend) -(0, 4pt) $ );

  end{tikzpicture}%

end{document}

documentclass[a4paper]{article}

usepackage{tikz}

    usetikzlibrary{decorations.pathreplacing}

begin{document}

    begin{tikzpicture}[node distance = 3cm]

        node at (-1,1){Cr: 3};

        draw[->](-0.5,1.1)--(-0.5,0.8);

        node at (-1,-1){C: 2};

        draw[->](-0.5,-1.1)--(-0.5,-0.8);

        draw [->] (0,1) --(1,-1);

        draw [->]  (0,-1) -- (1,1);

        draw[decorate,decoration={brace}]  (-0.3,1.2) -- (-0.3,-1.2);

        node at (1.7, 1.0){2 Cr: 6};

        node at (1.7, -1.0){3Cr: 6};

        draw[->](2.4,-1.1)--(2.4,-0.9);

        draw[->](2.4,1.1)--(2.4,0.9);

    end{tikzpicture}

end{document}