158:
72:
1454:
1466:
135:. For example, Aston discovered that neon has two isotopes with masses very close to 20 and 22 as per the whole number rule, and proposed that the non-integer value 20.2 for the atomic weight of neon is due to the fact that natural neon is a mixture of about 90% neon-20 and 10% neon-22). A secondary cause of deviations is the
20:
1259:
1269:
1319:
431:
William Prout (1816). Correction of a mistake in the essay on the relation between the specific gravities of bodies in their gaseous state and the weights of their atoms.
1416:
1294:
1299:
1274:
720:
1254:
970:
119:. He then hypothesized that the hydrogen atom was the fundamental object and that the other elements were a combination of different numbers of hydrogen atoms.
1383:
1393:
1388:
1329:
1289:
1284:
1244:
1304:
1239:
1025:
1398:
1378:
1165:
1234:
1198:
1279:
1229:
173:
During the 1920s, it was thought that the atomic nucleus was made of protons and electrons, which would account for the disparity between the
1324:
1249:
1160:
327:
758:
713:
1193:
1150:
413:
William Prout (1815). On the relation between the specific gravities of bodies in their gaseous state and the weights of their atoms.
464:
1469:
1366:
1314:
1188:
1351:
706:
1343:
1264:
1154:
189:. The fact that the atomic nucleus is composed of protons and neutrons was rapidly accepted and Chadwick was awarded the
1373:
80:
87:
around 1800 and states that all samples of a chemical compound will have the same elemental composition by mass. The
1491:
1208:
1141:
63:, of isotopes, in a large number of non-radioactive elements, and for his enunciation of the whole-number rule."
286:"On the relation between the specific gravities of bodies in their gaseous state and the weights of their atoms"
743:
152:
602:
1496:
1457:
1426:
935:
930:
925:
920:
877:
748:
636:"The Separation of Chlorine into Isotopes (Isotopic Elements) and the Whole Number Rule for Atomic Weights"
241:
Budzikiewicz H, Grigsby RD (2006). "Mass spectrometry and isotopes: a century of research and discussion".
947:
774:
631:
221:
190:
693:
220:
and isotopes with an error of at most 1%, with most of the error explained by the mass deficit caused by
23:
Francis W. Aston received the 1922 Nobel Prize in
Chemistry for his enunciation of the whole-number rule.
1421:
1002:
44:
1103:
787:
647:
606:
574:
520:
415:
290:
250:
343:
1020:
1108:
1068:
1203:
1073:
675:
460:
323:
317:
266:
185:
discovered an uncharged particle of approximately the mass as the proton, which he called the
166:
128:
60:
1438:
1361:
1356:
1180:
1132:
997:
955:
915:
910:
905:
900:
895:
890:
885:
837:
832:
827:
665:
655:
582:
565:
528:
493:
351:
258:
209:
157:
56:
131:
that apparent deviations from Prout's hypothesis are predominantly due to the existence of
1309:
1170:
822:
817:
812:
807:
802:
797:
792:
59:
who was awarded the Nobel Prize in
Chemistry in 1922 "for his discovery, by means of his
651:
578:
524:
254:
99:
with one kind of atom for each element combined in fixed proportions to form compounds.
71:
1118:
1113:
1083:
1078:
1063:
729:
670:
635:
182:
136:
36:
19:
1485:
448:
174:
162:
112:
108:
88:
84:
48:
212:(approximate mass of a proton, neutron, or hydrogen-1 atom). This rule predicts the
1433:
1098:
1093:
847:
782:
436:
1213:
1088:
842:
453:
213:
205:
197:
178:
140:
92:
987:
497:
401:
380:
1043:
1012:
867:
857:
852:
420:
285:
28:
679:
660:
270:
51:
are multiples of the weight of the hydrogen atom. It is also known as the
1035:
992:
132:
116:
40:
862:
217:
201:
186:
532:
262:
587:
560:
95:
expanded this concept and explained matter as consisting of discrete
481:
979:
156:
70:
18:
698:
96:
702:
115:
of the elements were whole multiples of the atomic weight of
127:
In 1920, Francis W. Aston demonstrated through the use of a
161:
James
Chadwick, discoverer of the neutron, with General
511:
Brown, Laurie M. (1978). "The idea of the neutrino".
196:
The modern form of the whole number rule is that the
545:
Friedlander G., Kennedy J.W. and Miller J.M. (1964)
387:, Cambridge, MA: Harvard, 1952. Accessed 2008-05-08.
1409:
1342:
1222:
1179:
1140:
1131:
1056:
1034:
1011:
978:
968:
946:
876:
773:
766:
757:
736:
383:, in Henry M. Leicester and Herbert S. Klickstein,
319:
Academic Press
Dictionary of Science and Technology
452:
75:John Dalton's list of atomic weights and symbols
322:. Gulf Professional Publishing. pp. 169–.
714:
398:A New System of Chemical Philosophy, volume 1
8:
371:Proust, J.-L. (1799). Researches on copper,
208:(number of protons plus neutrons) times an
35:states that the masses of the isotopes are
1137:
975:
770:
763:
721:
707:
699:
669:
659:
586:
549:(2nd edition), Wiley, pp. 22–23 and 38–39
43:atom. The rule is a modified version of
233:
482:"The constitution of atmospheric neon"
385:A Source Book in Chemistry, 1400-1900
122:
111:reported on his observation that the
47:proposed in 1815, to the effect that
7:
694:1922 Nobel Prize Presentation Speech
1465:
344:"The Nobel Prize in Chemistry 1922"
14:
561:"Possible Existence of a Neutron"
1464:
1453:
1452:
783:1 (Hydrogen and alkali metals)
316:Christopher G. Morris (1992).
1:
1325:Thermal expansion coefficient
1021:Lists of metalloids by source
123:Aston's discovery of isotopes
39:multiples of the mass of the
640:Proc. Natl. Acad. Sci. U.S.A
603:"James Chadwick – Biography"
143:of the individual isotopes.
1064:Platinum-group metals (PGM)
767:By periodic table structure
193:in 1935 for his discovery.
81:law of definite proportions
67:Law of definite proportions
1513:
1209:Goldschmidt classification
547:Nuclear and Radiochemistry
480:Aston, Francis W. (1920).
150:
102:
16:Rule of thumb in chemistry
1447:
788:2 (Alkaline earth metals)
498:10.1080/14786440408636058
243:Mass Spectrometry Reviews
559:Chadwick, James (1932).
153:Discovery of the neutron
147:Discovery of the neutron
1427:systematic element name
1399:in East Asian languages
749:Extended periodic table
284:Prout, William (1815).
53:Aston whole number rule
1270:Electron configuration
1260:Electrical resistivity
1199:Electron configuration
1003:Post-transition metals
661:10.1073/pnas.11.10.624
486:Philosophical Magazine
404:. Accessed 2008-05-08.
222:nuclear binding energy
191:Nobel Prize in Physics
170:
76:
24:
1104:Transuranium elements
204:is approximately the
200:of a given elemental
160:
74:
22:
1320:Thermal conductivity
1295:Heat of vaporization
737:Periodic table forms
607:The Nobel Foundation
433:Annals of Philosophy
419:, 6: 321–330.
416:Annals of Philosophy
291:Annals of Philosophy
1352:Element discoveries
1109:Superheavy elements
1069:Rare-earth elements
652:1925PNAS...11..624H
579:1932Natur.129Q.312C
525:1978PhT....31i..23B
435:, 7: 111–13.
396:Dalton, J. (1808).
255:2006MSRv...25..146B
177:of an atom and its
171:
165:, director of the
103:Prout's hypothesis
83:was formulated by
77:
45:Prout's hypothesis
25:
1492:Mass spectrometry
1479:
1478:
1338:
1337:
1300:Ionization energy
1275:Electronegativity
1265:Electron affinity
1204:Electronegativity
1194:Crystal structure
1189:Aqueous chemistry
1166:Nuclear stability
1161:Atomic properties
1127:
1126:
1074:Refractory metals
1052:
1051:
998:Transition metals
964:
963:
533:10.1063/1.2995181
329:978-0-12-200400-1
263:10.1002/mas.20061
167:Manhattan Project
129:mass spectrometer
61:mass spectrograph
33:whole number rule
1504:
1468:
1467:
1456:
1455:
1439:Dmitri Mendeleev
1367:1869 predictions
1357:Dmitri Mendeleev
1138:
976:
956:Aufbau principle
868:18 (Noble gases)
771:
764:
759:Sets of elements
723:
716:
709:
700:
683:
673:
663:
618:
617:
615:
613:
599:
593:
592:
590:
588:10.1038/129312a0
556:
550:
543:
537:
536:
508:
502:
501:
477:
471:
470:
458:
455:The God Particle
445:
439:
429:
423:
411:
405:
394:
388:
369:
363:
362:
360:
359:
352:Nobel Foundation
340:
334:
333:
313:
307:
306:
304:
303:
281:
275:
274:
238:
210:atomic mass unit
57:Francis W. Aston
1512:
1511:
1507:
1506:
1505:
1503:
1502:
1501:
1482:
1481:
1480:
1475:
1443:
1405:
1334:
1310:Oxidation state
1218:
1175:
1123:
1119:Minor actinides
1114:Major actinides
1079:Precious metals
1048:
1030:
1007:
960:
942:
872:
858:16 (Chalcogens)
853:15 (Pnictogens)
753:
732:
727:
690:
630:
627:
625:Further reading
622:
621:
611:
609:
601:
600:
596:
558:
557:
553:
544:
540:
510:
509:
505:
479:
478:
474:
467:
447:
446:
442:
430:
426:
412:
408:
395:
391:
370:
366:
357:
355:
342:
341:
337:
330:
315:
314:
310:
301:
299:
283:
282:
278:
240:
239:
235:
230:
155:
149:
125:
105:
69:
17:
12:
11:
5:
1510:
1508:
1500:
1499:
1497:Periodic table
1494:
1484:
1483:
1477:
1476:
1474:
1473:
1461:
1448:
1445:
1444:
1442:
1441:
1436:
1431:
1430:
1429:
1424:
1413:
1411:
1407:
1406:
1404:
1403:
1402:
1401:
1396:
1391:
1386:
1381:
1371:
1370:
1369:
1364:
1359:
1348:
1346:
1340:
1339:
1336:
1335:
1333:
1332:
1330:Vapor pressure
1327:
1322:
1317:
1315:Speed of sound
1312:
1307:
1302:
1297:
1292:
1290:Heat of fusion
1287:
1282:
1277:
1272:
1267:
1262:
1257:
1252:
1247:
1245:Critical point
1242:
1237:
1232:
1226:
1224:
1220:
1219:
1217:
1216:
1211:
1206:
1201:
1196:
1191:
1185:
1183:
1177:
1176:
1174:
1173:
1168:
1163:
1158:
1146:
1144:
1135:
1129:
1128:
1125:
1124:
1122:
1121:
1116:
1111:
1106:
1101:
1096:
1091:
1086:
1084:Coinage metals
1081:
1076:
1071:
1066:
1060:
1058:
1054:
1053:
1050:
1049:
1047:
1046:
1040:
1038:
1032:
1031:
1029:
1028:
1023:
1017:
1015:
1009:
1008:
1006:
1005:
1000:
995:
990:
984:
982:
973:
966:
965:
962:
961:
959:
958:
952:
950:
944:
943:
941:
940:
939:
938:
933:
928:
918:
913:
908:
903:
898:
893:
888:
882:
880:
874:
873:
871:
870:
865:
860:
855:
850:
845:
840:
835:
830:
825:
820:
815:
810:
805:
800:
795:
790:
785:
779:
777:
768:
761:
755:
754:
752:
751:
746:
740:
738:
734:
733:
730:Periodic table
728:
726:
725:
718:
711:
703:
697:
696:
689:
688:External links
686:
685:
684:
626:
623:
620:
619:
594:
551:
538:
503:
492:(6): 449–455.
472:
465:
449:Lederman, Leon
440:
437:Online reprint
424:
421:Online reprint
406:
400:, Manchester.
389:
364:
348:nobelprize.org
335:
328:
308:
276:
232:
231:
229:
226:
183:James Chadwick
151:Main article:
148:
145:
137:binding energy
124:
121:
113:atomic weights
104:
101:
68:
65:
49:atomic weights
15:
13:
10:
9:
6:
4:
3:
2:
1509:
1498:
1495:
1493:
1490:
1489:
1487:
1472:
1471:
1462:
1460:
1459:
1450:
1449:
1446:
1440:
1437:
1435:
1432:
1428:
1425:
1423:
1420:
1419:
1418:
1415:
1414:
1412:
1408:
1400:
1397:
1395:
1392:
1390:
1387:
1385:
1384:controversies
1382:
1380:
1377:
1376:
1375:
1372:
1368:
1365:
1363:
1360:
1358:
1355:
1354:
1353:
1350:
1349:
1347:
1345:
1341:
1331:
1328:
1326:
1323:
1321:
1318:
1316:
1313:
1311:
1308:
1306:
1305:Melting point
1303:
1301:
1298:
1296:
1293:
1291:
1288:
1286:
1285:Heat capacity
1283:
1281:
1278:
1276:
1273:
1271:
1268:
1266:
1263:
1261:
1258:
1256:
1253:
1251:
1248:
1246:
1243:
1241:
1240:Boiling point
1238:
1236:
1235:Atomic radius
1233:
1231:
1228:
1227:
1225:
1221:
1215:
1212:
1210:
1207:
1205:
1202:
1200:
1197:
1195:
1192:
1190:
1187:
1186:
1184:
1182:
1178:
1172:
1169:
1167:
1164:
1162:
1159:
1156:
1152:
1148:
1147:
1145:
1143:
1139:
1136:
1134:
1130:
1120:
1117:
1115:
1112:
1110:
1107:
1105:
1102:
1100:
1099:Native metals
1097:
1095:
1092:
1090:
1087:
1085:
1082:
1080:
1077:
1075:
1072:
1070:
1067:
1065:
1062:
1061:
1059:
1055:
1045:
1042:
1041:
1039:
1037:
1033:
1027:
1026:Dividing line
1024:
1022:
1019:
1018:
1016:
1014:
1010:
1004:
1001:
999:
996:
994:
991:
989:
986:
985:
983:
981:
977:
974:
972:
967:
957:
954:
953:
951:
949:
945:
937:
934:
932:
929:
927:
924:
923:
922:
919:
917:
914:
912:
909:
907:
904:
902:
899:
897:
894:
892:
889:
887:
884:
883:
881:
879:
875:
869:
866:
864:
863:17 (Halogens)
861:
859:
856:
854:
851:
849:
846:
844:
841:
839:
836:
834:
831:
829:
826:
824:
821:
819:
816:
814:
811:
809:
806:
804:
801:
799:
796:
794:
791:
789:
786:
784:
781:
780:
778:
776:
772:
769:
765:
762:
760:
756:
750:
747:
745:
742:
741:
739:
735:
731:
724:
719:
717:
712:
710:
705:
704:
701:
695:
692:
691:
687:
681:
677:
672:
667:
662:
657:
653:
649:
646:(10): 624–8.
645:
641:
637:
633:
629:
628:
624:
608:
604:
598:
595:
589:
584:
580:
576:
573:(3252): 312.
572:
568:
567:
562:
555:
552:
548:
542:
539:
534:
530:
526:
522:
518:
514:
513:Physics Today
507:
504:
499:
495:
491:
487:
483:
476:
473:
468:
466:9780385312110
462:
457:
456:
450:
444:
441:
438:
434:
428:
425:
422:
418:
417:
410:
407:
403:
399:
393:
390:
386:
382:
378:
374:
368:
365:
353:
349:
345:
339:
336:
331:
325:
321:
320:
312:
309:
297:
293:
292:
287:
280:
277:
272:
268:
264:
260:
256:
252:
249:(1): 146–57.
248:
244:
237:
234:
227:
225:
223:
219:
215:
211:
207:
203:
199:
194:
192:
188:
184:
180:
176:
175:atomic number
168:
164:
163:Leslie Groves
159:
154:
146:
144:
142:
138:
134:
130:
120:
118:
114:
110:
109:William Prout
100:
98:
94:
90:
89:atomic theory
86:
85:Joseph Proust
82:
73:
66:
64:
62:
58:
54:
50:
46:
42:
38:
34:
30:
21:
1463:
1451:
1434:Trivial name
1422:nomenclature
1094:Heavy metals
1089:Noble metals
848:14 (Tetrels)
744:Alternatives
643:
639:
610:. Retrieved
597:
570:
564:
554:
546:
541:
519:(9): 23–28.
516:
512:
506:
489:
485:
475:
454:
443:
432:
427:
414:
409:
397:
392:
384:
376:
372:
367:
356:. Retrieved
347:
338:
318:
311:
300:. Retrieved
295:
289:
279:
246:
242:
236:
195:
172:
126:
106:
78:
52:
37:whole number
32:
26:
1470:WikiProject
1214:Term symbol
1044:Noble gases
988:Lanthanides
971:metallicity
843:13 (Triels)
214:atomic mass
206:mass number
198:atomic mass
181:. In 1932,
179:atomic mass
141:mass defect
93:John Dalton
1486:Categories
1394:for people
1389:for places
1362:1871 table
1255:Elasticity
1223:Data pages
1181:Properties
1057:Other sets
1013:Metalloids
632:Harkins WD
373:Ann. chim.
358:2014-08-13
302:2007-09-08
228:References
1379:etymology
1230:Abundance
1155:in humans
1151:Abundance
1036:Nonmetals
993:Actinides
298:: 321–330
107:In 1815,
29:chemistry
1458:Category
1410:See also
1280:Hardness
1133:Elements
680:16587053
634:(1925).
612:21 April
451:(1993).
379::26-54.
271:16134128
218:nuclides
133:isotopes
117:hydrogen
41:hydrogen
1344:History
1250:Density
878:Periods
671:1086175
648:Bibcode
575:Bibcode
521:Bibcode
402:Excerpt
381:Excerpt
251:Bibcode
202:isotope
187:neutron
1374:Naming
1171:Symbol
980:Metals
948:Blocks
936:Pyykkö
931:Fricke
926:Aufbau
775:Groups
678:
668:
566:Nature
463:
354:. 1922
350:. The
326:
269:
55:after
31:, the
1417:IUPAC
1142:Lists
97:atoms
1149:By:
676:PMID
614:2013
461:ISBN
324:ISBN
267:PMID
79:The
969:By
666:PMC
656:doi
583:doi
571:129
529:doi
494:doi
259:doi
216:of
139:or
91:of
27:In
1488::
921:8+
838:12
833:11
828:10
674:.
664:.
654:.
644:11
642:.
638:.
605:.
581:.
569:.
563:.
527:.
517:31
515:.
490:39
488:.
484:.
459:.
377:32
375:,
346:.
294:.
288:.
265:.
257:.
247:25
245:.
224:.
1157:)
1153:(
916:7
911:6
906:5
901:4
896:3
891:2
886:1
823:9
818:8
813:7
808:6
803:5
798:4
793:3
722:e
715:t
708:v
682:.
658::
650::
616:.
591:.
585::
577::
535:.
531::
523::
500:.
496::
469:.
361:.
332:.
305:.
296:6
273:.
261::
253::
169:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
