diff --git a/CGRtools/periodictable/groupXV.py b/CGRtools/periodictable/groupXV.py
index <HASH>..<HASH> 100644
--- a/CGRtools/periodictable/groupXV.py
+++ b/CGRtools/periodictable/groupXV.py
@@ -33,11 +33,11 @@ class N(Element, PeriodII, GroupXV):
 
     @property
     def isotopes_distribution(self):
-        return FrozenDict({14: 0.99632, 15: 0.00368})
+        return FrozenDict({13: .0, 14: 0.99632, 15: 0.00368})
 
     @property
     def isotopes_masses(self):
-        return FrozenDict({14: 14.003074, 15: 15.000109})
+        return FrozenDict({13: 13.005738, 14: 14.003074, 15: 15.000109})
 
     @property
     def _common_valences(self):
Updated nitrogen

Updated nitrogen with isotope <I>