Table 4. Mean bond-length statistics for the five common alkali-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
Li+	3	4	1.913	0.032	0.070	1.958	1.888	–	–
	4	419	1.972	0.039	0.287	2.162	1.875	0.803	2.171
	5	91	2.108	0.050	0.214	2.226	2.012	–	–
	6	173	2.178	0.052	0.311	2.360	2.048	0.886	1.192
	7	2	2.331	0.008	0.012	2.337	2.326	–	–
	8	1	2.513	–	–	2.513	2.513	–	–
Na+	3	7	2.307	0.045	0.112	2.360	2.248	–	–
	4	131	2.359	0.049	0.285	2.537	2.252	0.784	0.937
	5	142	2.413	0.049	0.269	2.561	2.292	0.209	−0.034
	6	920	2.441	0.056	0.466	2.682	2.216	0.295	2.367
	7	193	2.541	0.056	0.313	2.718	2.404	0.423	0.021
	8	201	2.599	0.071	0.458	2.880	2.422	0.574	1.160
	9	50	2.686	0.065	0.382	2.936	2.553	–	–
	10	17	2.741	0.054	0.183	2.830	2.647	–	–
	12	21	2.795	0.074	0.254	2.940	2.686	–	–
K+	4	24	2.708	0.056	0.234	2.852	2.618	–	–
	5	59	2.796	0.078	0.438	3.084	2.646	–	–
	6	119	2.828	0.103	0.652	3.099	2.447	0.022	1.007
	7	67	2.861	0.064	0.295	3.009	2.715	–	–
	8	284	2.894	0.053	0.299	3.081	2.781	0.619	0.462
	9	308	2.955	0.061	0.503	3.174	2.671	−0.003	2.167
	10	243	3.013	0.065	0.382	3.209	2.827	0.384	0.493
	11	87	3.089	0.066	0.306	3.242	2.936	–	–
	12	194	3.095	0.092	0.543	3.337	2.794	−0.708	1.232
	13	35	3.149	0.094	0.327	3.293	2.966	–	–
	14	24	3.239	0.068	0.288	3.374	3.085	–	–
	15	35	3.182	0.064	0.246	3.332	3.086	–	–
Rb+	4	12	2.776	0.634	2.252	3.018	0.765	–	–
	5	3	2.864	0.040	0.078	2.899	2.821	–	–
	6	14	2.989	0.084	0.286	3.122	2.836	–	–
	7	20	3.002	0.083	0.371	3.213	2.842	–	–
	8	60	3.033	0.058	0.260	3.182	2.922	–	–
	9	75	3.079	0.064	0.321	3.287	2.966	–	–
	10	108	3.142	0.064	0.302	3.279	2.977	−0.262	−0.405
	11	44	3.188	0.054	0.226	3.296	3.070	–	–
	12	70	3.228	0.084	0.373	3.410	3.037	–	–
	13	19	3.293	0.042	0.138	3.350	3.212	–	–
	14	20	3.301	0.061	0.235	3.400	3.164	–	–
	15	13	3.338	0.110	0.337	3.545	3.208	–	–
	17	1	3.456	–	0.000	3.456	3.456	–	–
	18	5	3.478	0.078	0.217	3.582	3.364	–	–
Cs+	6	17	3.124	0.032	0.113	3.175	3.062	–	–
	7	10	3.193	0.061	0.206	3.312	3.106	–	–
	8	25	3.244	0.064	0.216	3.359	3.143	–	–
	9	48	3.251	0.054	0.232	3.366	3.134	–	–
	10	93	3.304	0.056	0.348	3.455	3.107	–	–
	11	68	3.333	0.054	0.261	3.479	3.218	–	–
	12	90	3.377	0.072	0.335	3.542	3.207	–	–
	13	40	3.426	0.063	0.267	3.552	3.285	–	–
	14	51	3.444	0.064	0.229	3.539	3.310	–	–
	15	47	3.503	0.066	0.289	3.661	3.372	–	–
	16	14	3.550	0.068	0.230	3.672	3.442	–	–
	17	4	3.530	0.029	0.062	3.549	3.487	–	–
	18	36	3.570	0.062	0.229	3.715	3.487	–	–
	20	1	3.723	–	–	3.723	3.723	–	–