Average atomic weight: 39.0983(1) u
| Isotope | Fraction | Atomic weight/u |
| 39 | 0.932581(44) | 38.9637064864(49) |
| 40 | 0.000117(1) | 39.963998166(60) |
| 41 | 0.067302(44) | 40.9618252579(41) |
Atomic weights and isotopic compositions were obtained from NIST Database 144
K I (K -like): 282 levels, 15194 lines (E1: 14309 IC: 885), transition probabilities for 4914 lines
K II (Ar-like): 29 levels, 141 lines (E1: 94 IC: 42 M1: 2 E2: 2 M2: 1), transition probabilities for 131 lines
K III (Cl-like): 39 levels, 280 lines (E1: 126 IC: 153 M1: 1), transition probabilities for 203 lines
K IV (S -like): 37 levels, 118 lines (E1: 61 IC: 48 M1: 5 E2: 4), transition probabilities for 107 lines
K V (P -like): 39 levels, 159 lines (E1: 74 IC: 72 M1: 7 E2: 6), transition probabilities for 154 lines
K VI (Si-like): 26 levels, 84 lines (E1: 41 IC: 31 M1: 5 E2: 7), transition probabilities for 78 lines
K VII (Al-like): 35 levels, 85 lines (E1: 80 M1: 2 E2: 3), transition probabilities for 40 lines
K VIII (Mg-like): 69 levels, 444 lines (E1: 422 IC: 18 M1: 2 E2: 2), transition probabilities for 190 lines
K IX (Na-like): 45 levels, 347 lines (E1: 347), transition probabilities for 347 lines
K X (Ne-like): 12 levels, 11 lines (E1: 5 IC: 6), transition probabilities for 7 lines
K XI (F -like): 28 levels, 77 lines (E1: 52 IC: 23 M1: 1 E2: 1), transition probabilities for 41 lines
K XII (O -like): 32 levels, 108 lines (E1: 53 IC: 43 M1: 5 E2: 7), transition probabilities for 103 lines
K XIII (N -like): 24 levels, 62 lines (E1: 54 IC: 2 M1: 2 E2: 4), transition probabilities for 2 lines
K XIV (C -like): 27 levels, 125 lines (E1: 55 IC: 53 M1: 5 E2: 7 M2: 5), transition probabilities for 121 lines
K XV (B -like): 24 levels, 79 lines (E1: 67 IC: 8 M1: 3 E2: 1), transition probabilities for 21 lines
K XVI (Be-like): 18 levels, 34 lines (E1: 26 IC: 4 M1: 2 E2: 2), transition probabilities for 24 lines
K XVII (Li-like): 25 levels, 115 lines (E1: 115), transition probabilities for 37 lines
K XVIII (He-like): 25 levels, 102 lines (E1: 68 IC: 33 M1: 1), transition probabilities for 69 lines
K XIX (H -like): 100 levels, 910 lines (E1: 910), transition probabilities for 910 lines
(Atomic Line List v3.00b5)
