Itemize spacing

Question

I don't use LaTeX that much, so I'm really clumsy with this stuff.

I've being searching for what I needed but since it appears there're no examples (or maybe I'm just bad at this) I decided to ask here.

I'm using some code that was giving to me in class, but I want to modify the way the itemize is looking.

\documentclass[final,letterpaper,twocolumn,authoryear,11pt]{elsarticle}
\usepackage{geometry}
\geometry{verbose,tmargin=2.5cm,bmargin=2.5cm,lmargin=2.5cm,rmargin=2.5cm}
\usepackage{enumitem}

\begin{document}
Donde,
\begin{itemize}  
\itemsep=0ex \itemindent=1cm 
\item[$K^B_A$:]  Constante de equilibrio químico, adim.
\item[$m_{A,liquid}$:] Concentración de A en la solución, mol/m\textsuperscript{3}.
\end{itemize}
\end{document}

I would like m_{A,liquid} to start just underneath K^B_A with the same spacing and, if it is possible, to make mol/m^3 move just underneath "Concentración".

Hope you could understand my question and help me!

Answer 1

I think a table is more suitable for you:

\documentclass[final,letterpaper,twocolumn,authoryear,11pt]{elsarticle}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{geometry}
\geometry{verbose,tmargin=2.5cm,bmargin=2.5cm,lmargin=2.5cm,rmargin=2.5cm}
\usepackage[spanish]{babel}
\usepackage{enumitem}
\usepackage{siunitx}
\usepackage{tabularx}

\begin{document}


\begin{tabularx}{\columnwidth}{@{}>{$}c<{$}X@{}}
K^B_A&Constante de equilibrio químico, adim.\\
m_{A,\mathrm{liquid}}&Concentración de A en la solución \si{mol/m^{3}}\\
\end{tabularx}

\end{document}

Produces

---

Recommendations

I would recommend

1. making the environment into a float, i.e. surrounding the tabularx with \begin{table} ... \end{table}

2. Abbreviate liquid to liq.

3. Read some resource for learning basic LaTeX (browse around the most voted questions)

---

NOTES AND USAGES

I would just like to point out:

• I added spanish babel (I think the language is spanish)

• I added fontenc and inputenc to support T1 fonts and UTF-8 input encoding

• I added siunitx to space correctly the unit of measure

• I added \mathrm{liquid} because you are typesetting in math, and that's how the words come out in roman font and correctly spaced. \text would've produced the same here, but in general uses the text font, thus not always yields the roman font. (Thanks to @barbarabeeton)

• I added tabularx to have the autoexpanding X column in tables (read the package documentation)

Answer 2

Like this, with enumitem and enumerate?

\documentclass[final, letterpaper, twocolumn, authoryear, 11pt]{elsarticle}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{geometry}
\geometry{verbose,margin=2.5cm, showframe}
\usepackage{amsmath}
\usepackage{enumitem}

\begin{document}

Donde,
\begin{enumerate}[wide, itemsep=0pt, leftmargin =*,widest={$m_{A,\mathrm{liquid}}$}]
  \item[$K^B_A$:] Constante de equilibrio químico, adim.
  \item[$m_{A,\text{liquid}}$:] Concentración de A en la solución, mol/m\textsuperscript{3}.
\end{enumerate}

\end{document} 

Answer 3

Two alternatives to enuitem and tabular-like environments:

1) The desclist package:

\documentclass[twocolumn,12pt]{elsarticle}
\usepackage[utf8]{inputenc}
\usepackage{desclist}
\begin{document}

\begin{desclist}{}{:}[$m_{A,\,liquid}$ ]
\item[$K^B_A$] Constante de equilibrio químico, adim. 
\item[$m_{A,\,liquid}$] Concentración de A en la 
                        solución, mol/m\textsuperscript{3}.
\end{desclist}
\end{document}

2) Just for fun, reinvent the wheel without packages and without lists. Instead of an environment, just a macro with two arguments for each item:

\documentclass[twocolumn,12pt]{elsarticle}
\usepackage[utf8]{inputenc}
\newlength\anchod
\settowidth{\anchod}{$m_{A,\,liquid}$: }
\def\describe#1#2{{\par\noindent\makebox[\anchod][l]%
{$#1$:}#2\hangindent\anchod\par}}
\begin{document}
\describe{K^B_A}{Constante de equilibrio químico, adim.} 
\describe{m_{A,\,liquid}}{Concentración de A en la 
solución, mol/m\textsuperscript{3}.}
\end{document}

In this case there are no more vertical spaces around each fake item that those of normal paragraphs. If that is not enough, you can change it locally with:

   {\setlength{\parskip}{\itemsep} 
    \describe{...}{...}
    ...  
    \describe{...}{...} 
    Normal paragraph\par}` 

The \itemsep is to mimic the spacing of true lists, but, of course, you can change \itemsep to anything else. Or you can add some spacers like \bigskip in the macro to avoid change the paragraphs skips.