actinium	u u	Ac	89	227 0 227 0
aluminum	s s	Al	13	26.9815385 0.0000007 26.982 0.0
americium	u u	Am	95	243 0 243 0 
antimony	g g	Sb	51	121.760 0.001 121.76 0.0
argon		gr gr	Ar	18	39.948 0.001 39.948 0.0
arsenic		s s	As	33	74.921595 0.000006 74.922 0.0
astatine	u u	At	85	210 0 210 0
barium		n n	Ba	56	137.327 0.007 137.33 0.0
berkelium	u u	Bk	97	247 0 247 0
beryllium	s s	Be	4	9.0121831 0.0000005 9.0122 0.0
bismuth		s s	Bi	83	208.98040 0.00001 208.98 0.0
bohrium		u u	Bh	107	270 274 0 0
boron		bm bm	B	5	10.806 10.821 10.806 10.821
bromine		b b	Br	35	79.901 79.907 79.901 79.907
cadmium		g g	Cd	48	112.414 0.004 112.41 0.0
cesium		s s	Cs	55	132.90545196 0.00000006 132.91 0.0
calcium		g g	Ca	20	40.078 0.004 40.078 0.004
californium	u u	Cf	98	251 0 251 0
carbon		b b	C	6	12.0096 12.0116 12.009 12.012 
cerium		g g	Ce	58	140.116 0.001 140.12 0.0
chlorine	bm bm	Cl	17	35.446 35.457 35.446 35.457
chromium	n n	Cr	24	51.9961 0.0006 51.996 0.0
cobalt		s s	Co	27	58.933194 0.000004 58.933 0.0
copernicium	u u	Cn	112	285 0 285 0
copper		r r	Cu	29	63.546 0.003 63.546 0.003
curium		u u	Cm	96	247 0 247 0
darmstadtium	u u	Ds	110	281 0 281 0 
dubnium		u u	Db	105	268 270 268 270
dysprosium	g g	Dy	66	162.500 0.001 162.50 0.0
einsteinium	u u	Es	99	252 0 252 0
erbium		g g	Er	68	167.259 0.003 167.26 0.0
europium	g g	Eu	63	151.964 0.001 151.96 0.0
fermium		u u	Fm	100	257 0 257 0
flerovium	u u	Fl	114	289 0 289 0
fluorine	s s	F	9	18.998403163 0.000000006 18.998 0.0
francium	u u	Fr	87	223 0 223 0
gadolinium	g n	Gd	64	157.25 0.03 157.25 0.03
gallium		n n	Ga	31	69.723 0.001 69.723 0.0
germanium	n n	Ge	32	72.630 0.008 72.630 0.008
gold		s s	Au	79	196.966569 0.000005 196.97 0.0
hafnium		n n	Hf	72	178.49 0.02 178.49 0.02
hassium		v v	Hs	108	269 277 269 277 
helium		gr n	He	2	4.002602 0.000002 4.0026 0.0
holmium		s s	Ho	67	164.93033 0.00002 164.93 0.0
hydrogen	bm bm	H	1	1.00784 1.00811 1.0078 1.0082
indium		n n	In	49	114.818 0.001 114.82 0.0
iodine		s s	I	53	126.90447 0.00003 126.90 0.0
iridium		n n	Ir	77	192.217 0.003 192.22 0.0
iron		n n	Fe	26	55.845 0.002 55.845 0.002
krypton		gm gm	Kr	36	83.798 0.002 83.798 0.002
lanthanum	g n	La	57	138.90547 0.00007 138.91 0.0
lawrencium	u u	Lr	103	262 0 262 0
lead		gr gr	Pb	82	207.2 0.1 207.2 0.0
lithium		bm bm	Li	3	6.938 6.997 6.938 6.997
livermorium	u u	Lv	116	293 0 293 0
lutetium	g g	Lu	71	174.9668 0.0001 174.97 0.0
magnesium	b b	Mg	12	24.304 24.307 24.304 24.307
manganese	s s	Mn	25	54.938044 0.000003 54.938 0.0
meitnerium	v v	Mt	109	276 278 276 278
mendelevium	u u	Md	101	258 0 258 0
mercury		n n	Hg	80	200.592 0.003 200.59 0.0
molybdenum	g g	Mo	42	95.95 0.01 95.95 0.0
neodymium	g g	Nd	60	144.242 0.003 144.24 0.0
neon		gm m	Ne	10	20.1797 0.0006 20.180 0.0
neptunium	u u	Np	93	237 0 237 0
nickel		r r	Ni	28	58.6934 0.0004 58.693 0.0
niobium		s s	Nb	41	92.90637 0.00002 92.906 0.0
nitrogen	b b	nn	7	14.00643 14.00728 14.006 14.008
nobelium	u u	No	102	259 0 259 0
osmium		g g	Os	76	190.23 0.03 190.23 0.03
oxygen		b b	O	8	15.99903 15.99977 15.999 16.000
palladium	g g	Pd	46	106.42 0.01 106.42 0.0
phosphorus	s s	P	15	30.973761998 0.000000005 30.974 0.0
platinum	n n	Pt	78	195.084 0.009 195.08 0.0
plutonium	u u	Pu	94	244 0 244 0
polonium	u u	Po	84	209 0 209 0
potassium	n n	K	19	39.0983 (1) 39.098 0.0
praseodymium	s s	Pr	59	140.90766 (2) 140.91 0.0
promethium	u u	Pm	61	145 0 145 0 
protactinium	s s	Pa	91	231.03588 (2) 231.04 0.0
radium		u u	Ra	88	226 0 226 0
radon		u u	Rn	86	222 0 222 0
rhenium		n n	Re	75	186.207 (1) 186.21 0.0
rhodium		s s	Rh	45	102.90550 (2) 102.91 0.0
roentgenium	u u	Rg	111	281 0 281 0
rubidium	g g	Rb	37	85.4678 (3) 85.468 0.0
ruthenium	g g	Ru	44	101.07 (2) 101.07 (2)
rutherfordium	u u	Rf	104	267 0 267 0
samarium	g g	Sm	62	150.36 (2) 150.36 (2)
scandium	s s	Sc	21	44.955908 (5) 44.956 0.0
seaborgium	v v	Sg	106	269 271 269 271 
selenium	r r	Se	34	78.971 (8) 78.971 (8)
silicon		b b	Si	14	28.084 28.086 28.084 28.086
silver		g g	Ag	47	107.8682 (2) 107.87 0.0
sodium		s s	Na	11	22.98976928 (2) 22.990 0.0
strontium	gr gr	Sr	38	87.62 (1) 87.62 0.0
sulfur		b b	S	16	32.059 32.076 32.059 32.076
tantalum	n n	Ta	73	180.94788 (2) 180.95 0.0 
technetium	v v	Tc	43	97 98 97 98
tellurium	g g	Te	52	127.60 (3) 127.60 (3)
terbium		s s	Tb	65	158.92535 (2) 158.93 0.0
thallium	b b	Tl	81	204.382 204.385 204.38 204.39
thorium		n n	Th	90	232.0377 (4) 232.04 0.0
thulium		s s	Tm	69	168.93422 (2) 168.93 0.0
tin		g g	Sn	50	118.710 (7) 118.71 0.0
titanium	n n	Ti	22	47.867 (1) 47.867 0.0
tungsten	n n	W	74	183.84 (1) 183.84 0.0
oganesson	u u	Og	118	294 0 294 0
moscovium	u u	Mo	115	288 0 288 0
tennessine	u u	Tn	117	294 0 294 0
nihonium	u u	Nh	113	286 0 286 0
uranium		gm gm	U	92	238.02891 (3) 238.03 0.0
vanadium	n n	V	23	50.9415 (1) 50.942 0.0
xenon		gm gm	Xe	54	131.293 (6) 131.29 0.0
ytterbium	g g	Yb	70	173.054 (5) 173.05 0.0
yttrium		s s	Y	39	88.90584 (2) 88.906 0.0
zinc		r r	Zn	30	65.38 (2) 65.38 (2) 
zirconium	g g	Zr	40	91.224 (2) 91.224 (2) 

g: Geological specimens are known in which the element has an isotopic
composition outside the limits for normal material. The difference
between the atomic weight of the element in such materials and that
given in the table may exceed the stated uncertainty.

m: Modified isotopic compositions may be found in commercially
available material because the material has been subjected to an
undisclosed or inadvertent isotopic fractionation. Substantial
deviations in atomic weight of the element from that given in the
table can occur.

r: Range in isotopic composition of normal terrestrial material
prevents a more precise Ar(E) being given; the tabulated Ar(E) value
and and uncertainty should be applicable to normal material.

u: unstable

v: unstable with two longest-lived isotopes

n: normal

s: monoisotopic

b: bracketed range instead of centroid and error