How do I take chemistry notes on Mac?
If you know LaTeX and you want to see what you are writing you can use lyx, and some TeX package like mhchem and chemfig. So you can write all the things you want and add comments. This is what I have done with my Mac just now:

Here is the code, you can make these lines as a default template:

\documentclass[12pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage[left=2cm,right=2cm,top=2cm,bottom=2cm]{geometry}
\usepackage{chemfig}
\usepackage{tikz}
\usepackage[version=4]{mhchem}
\setlewis{4pt}{0.8em}{black}


From here you have to write! The date is automatically added!

\title{Introduction to chemistry notes}
\begin{document}
\maketitle
\section{mhchem}
You know that \ce{ CH4 + 2O2 -&gt; CO2 + 2H2O}     this is a simple equation\ldots
Okay maybe you can do this with word, but if you are familiar with Chemistry S.E. you will be very fast with this notation.

\ce{Zn^2+
&lt;=&gt;[\ce{+ 2OH-}][\ce{+ 2H+}]
$\underset{\text{amphoteres Hydroxid}}{\ce{Zn(OH)2 v}}$
&lt;=&gt;C[+2OH-][{+ 2H+}]
$\underset{\text{Hydroxozikat}}{\ce{[Zn(OH)4]^2-}}$
}



\section{Chemfig}
\begin{figure}[h]
\setatomsep{1.8em}
\schemestart
\subscheme[90]{\chemfig{*6((-[@{a1}]H_2@{a2}\Lewis{26,N})=[@{r1}]-[@{r2}]=[@{b2}](-[@{b1}]N =[@{c1}] N -[@{c2}]*6(=[@{d1}]-[@{d2}] =[@{e1}](-[@{e2}] OH)-=-))-=-=)}\chemrel{&lt;-&gt;}
\chemmove[-stealth,shorten &lt;=1pt, shorten &gt;=1pt]{%
    \draw(a2)..controls +(90:5mm) and +(135:5mm)..(a1);% first arrow
    \draw(r1)..controls +(225:12mm) and +(300:12mm)..(r2);% ring arrow
    \draw(b2)..controls +(10:3mm)..(b1);% ring arrow 
    \draw(c1)..controls +(340:8mm)..(c2);% ring arrow 
    \draw(d1)..controls +(225:12mm) and +(300:12mm)..(d2);% ring arrow
    \draw(e1)..controls +(20:4mm)..(e2);% ring arrow  
    }        
\chemfig{*6((=[@{a1}]H_2@{a2}\chemabove{N}{\oplus})-[@{r1}]=[@{r2}]-[@{b2}](=[@{b1}]N-[@{c1}] N =[@{c2}]*6(-[@{d1}]=[@{d2}] -[@{e1}](=[@{e2}] \chemabove{O}{\ominus}H)-=-))-=--)}
}
\schemestop
\caption{This is a coniguated system\ldots}
\label{fig:con}
\end{figure}
Okay the lesson will end and in one hour you'll draw this figure only, maybe you should use an external software\ldots %what the professor means whit this last phrase?! 
\end{document}


Sincerely I think that is best to take handwrite notes because I think that writing and drawing chemical formula allow you to memorize better but of course this is only a thought.