Standard atomic weights

"The atomic mass, m_a, of an unbound neutral atom of carbon-12, m_a(¹²C), in its nuclear and electronic ground states is 12 Da exactly, where Da is the symbol for unified atomic mass unit. The atomic mass of ¹²CC is 12 Da, and the atomic weight of ¹²CC is 12 exactly. All other atomic weight values are ratios to the ¹²C standard value and thus are dimensionless numbers."

Units

atomic mass units

Notes

Literature sources

J. Meija, T.B. Coplen, M. Berglund, W.A. Brand, P. De Bi�vre, M. Gr�ning, N.E. Holden, J. Irrgeher, R.D. Loss, T.Walczyk, and T. Prohaska, Atomic weights of the elements 2013 (IUPAC Technical Report), Pure Appl. Chem., 88, 265-291. doi:10.1515/pac-2015-0305.

Explore the element of your choice through this periodic table.
1	2		3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18
1 H			2 He
3 Li	4 Be		5 B	6 C	7 N	8 O	9 F	10 Ne
11 Na	12 Mg		13 Al	14 Si	15 P	16 S	17 Cl	18 Ar
19 K	20 Ca		21 Sc	22 Ti	23 V	24 Cr	25 Mn	26 Fe	27 Co	28 Ni	29 Cu	30 Zn	31 Ga	32 Ge	33 As	34 Se	35 Br	36 Kr
37 Rb	38 Sr		39 Y	40 Zr	41 Nb	42 Mo	43 Tc	44 Ru	45 Rh	46 Pd	47 Ag	48 Cd	49 In	50 Sn	51 Sb	52 Te	53 I	54 Xe
55 Cs	56 Ba	*	71 Lu	72 Hf	73 Ta	74 W	75 Re	76 Os	77 Ir	78 Pt	79 Au	80 Hg	81 Tl	82 Pb	83 Bi	84 Po	85 At	86 Rn
87 Fr	88 Ra	**	103 Lr	104 Rf	105 Db	106 Sg	107 Bh	108 Hs	109 Mt	110 Ds	111 Rg	112 Cn	113 Nh	114 Fl	115 Mc	116 Lv	117 Ts	118 Og

*Lanthanoids	*	57 La	58 Ce	59 Pr	60 Nd	61 Pm	62 Sm	63 Eu	64 Gd	65 Tb	66 Dy	67 Ho	68 Er	69 Tm	70 Yb
**Actinoids	**	89 Ac	90 Th	91 Pa	92 U	93 Np	94 Pu	95 Am	96 Cm	97 Bk	98 Cf	99 Es	100 Fm	101 Md	102 No

Explore the element of your choice through this periodic table.

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

*Lanthanoids

**Actinoids

100

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102