Table 2. Bond-length statistics for the five common alkaline-earth-metal ions.

Ion	Coordination number	Number of bonds	Number of coordination polyhedra	Mean bond length (Å)	Standard deviation (Å)	Range (Å)	Maximum bond length (Å)	Minimum bond length (Å)	Skewness	Kurtosis
Be2+	3	24	8	1.550	0.018	0.081	1.587	1.506	–	–
	4	644	161	1.637	0.040	0.346	1.887	1.541	1.988	8.529
	Total	668	169
Mg2+	4	48	12	1.939	0.020	0.068	1.977	1.909	–	–
	5	120	24	2.044	0.066	0.342	2.249	1.907	0.643	0.271
	6	2556	426	2.089	0.059	0.562	2.497	1.935	1.976	8.608
	8	56	7	2.255	0.122	0.568	2.582	2.014	–	–
	Total	2780	469
Ca2+	6	1266	211	2.371	0.069	0.637	2.847	2.210	1.636	5.908
	7	2009	287	2.448	0.133	1.016	3.140	2.124	1.828	4.607
	8	4152	519	2.498	0.151	1.027	3.176	2.149	1.430	2.739
	9	1035	115	2.559	0.196	0.956	3.197	2.241	1.247	0.939
	10	160	16	2.632	0.215	0.902	3.122	2.220	0.478	−0.400
	11	77	7	2.614	0.177	0.686	2.965	2.279	–	–
	12	156	13	2.668	0.175	0.791	3.117	2.326	0.724	0.379
	Total	8855	1168
Sr2+	6	78	13	2.477	0.050	0.244	2.591	2.347	–	–
	7	266	38	2.638	0.151	0.937	3.306	2.369	1.553	3.693
	8	904	113	2.656	0.163	1.019	3.368	2.349	1.711	3.740
	9	909	101	2.704	0.178	1.088	3.397	2.309	1.545	3.094
	10	500	50	2.769	0.213	1.033	3.399	2.366	0.962	0.456
	11	88	8	2.798	0.198	0.837	3.319	2.482	–	–
	12	636	53	2.825	0.181	0.953	3.358	2.405	0.744	0.613
	Total	3381	376
Ba2+	6	126	21	2.689	0.094	0.400	2.866	2.466	−0.404	−0.665
	7	147	21	2.792	0.135	0.855	3.369	2.514	1.133	2.916
	8	704	88	2.816	0.129	0.846	3.376	2.530	0.962	1.273
	9	1278	142	2.860	0.154	1.074	3.554	2.480	1.000	1.330
	10	1930	193	2.915	0.155	1.014	3.498	2.484	0.783	1.072
	11	902	82	2.944	0.181	1.023	3.612	2.589	0.667	0.074
	12	3624	302	2.965	0.152	0.988	3.624	2.636	1.239	1.951
	13	78	6	3.010	0.206	0.922	3.463	2.541	–	–
	14	14	1	3.080	0.242	0.879	3.553	2.674	–	–
	Total	8813	856