Table 5. Mean bond-length statistics for the five common alkaline-earth-metal ions.

Ion	Coordination number	Number of coordination polyhedra	Grand mean bond length (Å)	Standard deviation (Å)	Mean bond-length range (Å)	Maximum mean bond length (Å)	Minimum mean bond length (Å)	Skewness	Kurtosis
Be2+	3	8	1.550	0.012	0.031	1.566	1.535	–	–
	4	161	1.637	0.017	0.114	1.719	1.605	1.744	6.011
Mg2+	4	12	1.939	0.017	0.054	1.966	1.912	–	–
	5	24	1.966	0.091	0.309	2.087	1.777	–	–
	6	426	2.089	0.024	0.185	2.223	2.038	1.179	3.051
	8	7	2.255	0.035	0.080	2.284	2.203	–	–
Ca2+	6	211	2.371	0.034	0.217	2.471	2.254	−0.261	0.236
	7	287	2.447	0.038	0.225	2.591	2.366	0.735	0.761
	8	519	2.498	0.048	0.259	2.663	2.404	0.216	−0.238
	9	115	2.559	0.039	0.215	2.694	2.479	0.761	0.927
	10	16	2.632	0.048	0.137	2.686	2.549	–	–
	11	7	2.614	0.060	0.139	2.690	2.551	–	–
	12	13	2.668	0.073	0.228	2.777	2.549	–	–
Sr2+	6	13	2.477	0.034	0.118	2.542	2.424	–	–
	7	38	2.639	0.054	0.188	2.738	2.549	–	–
	8	113	2.658	0.061	0.310	2.871	2.561	1.298	1.633
	9	101	2.703	0.051	0.266	2.871	2.604	1.119	1.523
	10	50	2.769	0.070	0.436	3.053	2.617	–	–
	11	8	2.798	0.027	0.075	2.830	2.755	–	–
	12	53	2.825	0.055	0.213	2.930	2.716	–	–
Ba2+	6	21	2.689	0.054	0.197	2.794	2.597	–	–
	7	21	2.792	0.033	0.121	2.855	2.733	–	–
	8	88	2.816	0.049	0.254	2.952	2.698	–	–
	9	142	2.860	0.055	0.307	3.036	2.729	0.111	0.302
	10	193	2.915	0.053	0.295	3.091	2.796	0.282	−0.022
	11	82	2.944	0.039	0.187	3.035	2.849	–	–
	12	302	2.965	0.058	0.289	3.133	2.845	0.467	−0.299
	13	6	3.010	0.051	0.137	3.070	2.934	–	–
	14	1	3.080	–	–	3.080	3.080	–	–