Hi Gavin,

maybe you have solved your problem yet.

\startformula
 {\null}^^{194}__{38}{\rm Sr}
or  {\hbox{Xe}}^^{140}__{54}.
\stopformula

Better, ConTeXt way could be the variation on \chem:

\unexpanded\def\isotope#1#2#3{\dontleavehmode\begingroup\null\lohi[left]{#2}{#3}#1\endgroup}
\isotope{Sr}{38}{194}
or (with more logical order of parameters)
\unexpanded\def\isotope#1#2#3{\dontleavehmode\begingroup\null\lohi[left]{#1}{#2}#3\endgroup}
\isotope{38}{999}{Sr}

Or for text and math modes together:

\unexpanded\def\isotope#1#2#3{%
\ifmmode\begingroup\null^^{#1}__{#2}{\rm#3}\endgroup%
   \else\dontleavehmode\begingroup\null\lohi[left]{\tfx #1}{\tfx#2}\rm#3\endgroup%
\fi}

\isotope{999}{38}{Sr}
\startformula
\isotope{999}{38}{Sr}
\stopformula

You can do it either way, whichever way suits you better.

Tomáš


________________________________
Od: ntg-context <ntg-context-bounces@ntg.nl> za uživatele Hans Åberg via ntg-context <ntg-context@ntg.nl>
Odesláno: sobota 15. dubna 2023 22:41
Komu: mailing list for ConTeXt users <ntg-context@ntg.nl>
Kopie: Hans Åberg <haberg-1@telia.com>
Předmět: Re: [NTG-context] Nuclear reactions


> On 15 Apr 2023, at 19:19, Gavin via ntg-context <ntg-context@ntg.nl> wrote:
>
> I’m writing nuclear reactions. When add prescripts to atomic symbols with two letters, (Be, Sr, Xe, etc.) the prescripts split the atoms!

One can use Unicode superscript and subscript numbers, as in ²³⁵₉₂U, which is easier to read. For input, an editor supporting text substitutions might be used.


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