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Krypton (Kr) Element Properties

Atomic Mass	83.8
Atomic Number	36
Name Origins	From the Greek, kryptos = "hidden."
Year Discovered	1898
Discovery Credits	Discovered by Sir William Ramsay and M. W. Travers at London, UK.
Remarks	Colorless, odorless gas present in the atmosphere. Chemically inert to everything but fluorine. ⁸⁶Kr has an orange-red line in its atomic spectrum that is used for the SI length standard where 1 meter = 1,650,763.73 wavelengths. One meter was originally defined as 1 millionth the distance from the earth's pole to the equator.
References	Emsley, J., 1991; THE ELEMENTS : Sec. Ed., Clarendon Press, Oxford, 251 p.
See Also	WebElements, ChemiCool

**Naturally Occurring Isotopes**
Symbol	Isotope Mass	Isotope Nuclide Number	Isotope Number	Natural Abundance	Half-life Units
Kr	77.9204	79	36	0.3500%	Stable
Kr	79.91638	80	36	2.2500%	Stable
Kr	81.913482	82	36	11.6000%	Stable
Kr	82.914135	83	36	11.5000%	Stable
Kr	83.911507	84	36	57.0000%	Stable
Kr	85.910616	86	36	17.3000%	Stable

Group	1	2		3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18
Period
1	1 H																		2 He
2	3 Li	4 Be												5 B	6 C	7 N	8 O	9 F	10 Ne
3	11 Na	12 Mg												13 Al	14 Si	15 P	16 S	17 Cl	18 Ar
4	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
5	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
6	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
7	87 Fr	88 Ra	**	103 Lr	104 Rf	105 Db	106 Sg	107 Bh	108 Hs	109 Mt	110 Ds
-
*Lanthanides			*	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
**Actinides			**	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