query: SELECT ?element (SAMPLE(?symbol) AS ?symbol) (SAMPLE(?protons) AS ?protons) (MIN(?neutrons) AS ?minNeutrons) (MAX(?neutrons) AS ?maxNeutrons)
  WHERE
  {
    ?element wdt:P31 wd:Q11344;
             wdt:P1086 ?protons;
             wdt:P246 ?symbol.
    ?isotope wdt:P279 ?element;
             wdt:P1148 ?neutrons.
  }
  GROUP BY ?element
  ORDER BY ?protons