Arrangement of Atoms in Crystals. 



181 





Atomic 



Sums of radii, 



Observed 



Difference, 



Compound. 



Element Na. 



NaF. 



NaCl. 



NaBr. 



NaT. 



NaN0 3 . 



centres, 



Na,F, 



Na,Cl. 

 Na,Bi*. 

 Na,I. 

 Na,0. 



in A. Distance, in A. 

 3'55 3*72 

 1-77+0-67= 2'44 239 

 1-77 4- 1-05= 2-82 2-80 

 1-77 + 1*19=2-96 2-97 

 1-77+1*40=3-37 3-23 

 1-77+0-65=2-42 2-33 



in A. 



+017 

 -005 



+0-02 

 +0-01 

 -0-14 

 -0 09 



Element Mg. 



MgO. 



MgC0 3 . 



MgS. 



Mg.O. 

 Mg.O. 



Mg.S. 



2-85 

 1-42 + 000 = 2-07 

 ] -42 + 0-65 = 207 

 142 + 1-02 = 2-44 



3-22 

 210 

 2-00 

 254 



+ 0-37 

 +003 

 -0-07 

 +010 



Element Al. 

 A1 2 3 . 



Al.O. 



2-70 

 1-35+0-65=2-00 



2-87 

 2 02 



+0-17 

 +0-02 



KF. 

 KC1, 

 KBr. 

 KI. 



K,F. 



K.C1. 

 K,Br. 

 K,I. 



2-07+0-67=2-74 

 2 07 + 105 = 312 

 2-07+119=3-26 



2-07 + 1-40=347 



2-78 

 313 

 3-28 

 3-52 



+ 004 

 +0-01 

 +0-02 

 +0-05 



CaO. 

 CaC0 3 . 

 CaS. 

 CaF 2 . 



Ca,0. 



Ca,0. 

 Ca,S. 

 Ca,F. 



l-70+0-65=2-35 



1-70+0-65 = 2-35 

 1-70 +102 =2-72 

 1-70+0 65=2-35 



2-40 

 2-30 



277 

 2-34 



+0 05 

 - 005 

 +0-05 

 -0-01 



MnC0 3 . 



MnS 2 . 



Mn.O. 



Mn,S. 



1-47+0-65=2-11 



147+1-02=249 



210 



2-59 



-0-01 

 +0-10 



Element Fe. 

 FeC0 3 . 

 Fe„O v 

 Fe 3 C 4 . 



FeS 2 . 



Fe,0. 

 Fe,0. 

 Fe,0. 

 Fe,S. 



2-80 

 1-40+0-65=2*05 

 1-40+0-65=205 



1-40 +0-65 = 2-05 

 1-40 + 1-02 = 2-42 



247 

 2 04 

 2 10app 

 2-00 

 2-28 



-0-33 



-001 



>, +0-05 



-0-05 



-0-14 



Element Cu. 

 Cu,0. 



Cu,0. 



275 



1-37+0-65=2-02 



2-55 



1-87 



-0-20 

 -0-15 



ZnO. 

 ZnCO.,. 



ZnS. ' 



Zn.O. 

 Zn,0. 



Zn,S. 



1-32+0-65=1-97 

 1*32+0-65=1-97 

 1-32 + 1 -02=2-32 



1-97 

 1-99 

 2-35 



o-oo 



+0-02 

 +0-03 



EbCl. 

 RbBr, 

 Ebl. 



Eb.CI. 

 Eb,B>'. 

 EbJ. 



2-25 + 105 =3-30 

 2-25+119=3-44 

 2-25+1-40=3-65 



3-28 

 344 

 3-66 



-002 



o-oo 



+0-01 



SrO. 

 SrS. 



Sr.O. 



Sr,S. 



1-95+0-65=2-60 



1-95 + 1-02 = 2-97 



2-63 

 2-99 



+ 003 

 +0-02 



CdC0 3 . 

 CdS. 



Cd,0. 



Cd,S. 



1-60+0-65 = 2-25 

 160+102=2-62 



2-21 

 2-67 



-004 

 +0-05 



CsCl. 

 CsBr. 

 Osl. 



Cs,Cl. 

 Cs,Br. 

 Cs,I. 



237 + 1-05 =3-42 

 2-37 + 1-19=3*56 



2-37 + 140=3-77 



326 

 340 

 3C1 



-014 

 -0-16 



-0-16 



BaO. 

 BaS. 



Ba.O. 



Ba ; S. 



2-15+065=2-80 

 215+102=3-17 



2*81 



3-20 



+001 

 +003 



