How to make this kind of arrows on Latex?

Question

Also, how to center tikz pictures? I did what I wanted with curved arrows like this:

\documentclass[a4paper]{article}

\usepackage[T1]{fontenc}    
\usepackage[utf8]{inputenc}

\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage{mathtools}
\usepackage{tikz}
\usetikzlibrary{fit,shapes.geometric,arrows}

\begin{document}

\[ \tau\tikz[overlay,remember picture] \node (1){};\  \vee\neg\in\square\tikz[overlay,remember picture] \node (2){};\ A^\prime\in\square\tikz[overlay,remember picture] \node (3){};\ A^{\prime\prime} \] 

            \begin{tikzpicture}[node distance=1.5cm, auto, text centered, overlay, remember picture]
            \draw[->,>=stealth,bend left=60,shorten <= .2cm,shorten >= .2cm] (1.north) to (2.north);
            \draw[->,>=stealth,bend left=60,shorten <= .2cm,shorten >= .2cm] (1.north) to (3.north);
            \end{tikzpicture}

\end{document}

And I tried a lot of things to get it centered, but nothing has worked so far.

Answer 1

Almost this exact example is also to be found in the manual of chemmacros. Hence I suggest you use this package. Here is the example, slightly adapted to your use-case:

\documentclass{article}
\usepackage{chemmacros}
\usechemmodule{redox}
\chemsetup[redox]{explicit-sign=true}
\begin{document}

\ch{
  2 "\OX{o1,\ox*{0,Na}}" + "\OX{r1,\ox*{0,Cl}}" {}2
  ->
  2 "\OX{o2,\ox*{+1,Na}}" {}+ + 2 "\OX{r2,\ox*{-1,Cl}}" {}-
}
\redox(o1,o2)[->]{\small oxidation}
\redox(r1,r2)[->][-1]{\small reduction}

\end{document}