/usr/share/gromacs/top/elements.dat is in gromacs-data 4.5.5-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 | ??? H 1
??? He 2
??? Li 3
??? Be 4
??? B 5
??? C 6
??? N 7
??? O 8
??? F 9
??? Ne 10
??? Na 11
??? Mg 12
??? Al 13
??? Si 14
??? P 15
??? S 16
??? Cl 17
??? Ar 18
??? K 19
??? Ca 20
??? Sc 21
??? Ti 22
??? V 23
??? Cr 24
??? Mn 25
??? Fe 26
??? Co 27
??? Ni 28
??? Cu 29
??? Zn 30
??? Ga 31
??? Ge 32
??? As 33
??? Se 34
??? Br 35
??? Kr 36
??? Rb 37
??? Sr 38
??? Y 39
??? Zr 40
??? Nb 41
??? Mo 42
??? Tc 43
??? Ru 44
??? Rh 45
??? Pd 46
??? Ag 47
??? Cd 48
??? In 49
??? Sn 50
??? Sb 51
??? Te 52
??? I 53
??? Xe 54
??? Cs 55
??? Ba 56
??? La 57
??? Ce 58
??? Pr 59
??? Nd 60
??? Pm 61
??? Sm 62
??? Eu 63
??? Gd 64
??? Tb 65
??? Dy 66
??? Ho 67
??? Er 68
??? Tm 69
??? Yb 70
??? Lu 71
??? Hf 72
??? Ta 73
??? W 74
??? Re 75
??? Os 76
??? Ir 77
??? Pt 78
??? Au 79
??? Hg 80
??? Tl 81
??? Pb 82
??? Bi 83
??? Po 84
??? At 85
??? Rn 86
??? Fr 87
??? Ra 88
??? Ac 89
??? Th 90
??? Pa 91
??? U 92
??? Np 93
??? Pu 94
??? Am 95
??? Cm 96
??? Bk 97
??? Cf 98
??? Es 99
??? Fm 100
??? Md 101
??? No 102
??? Lr 103
??? Rf 104
??? Db 105
??? Sg 106
??? Bh 107
??? Hs 108
??? Mt 109
??? Hydrogen 1
??? Helium 2
??? Lithium 3
??? Beryllium 4
??? Boron 5
??? Carbon 6
??? Nitrogen 7
??? Oxygen 8
??? Fluorine 9
??? Neon 10
??? Sodium 11
??? Magnesium 12
??? Aluminum 13
??? Silicon 14
??? Phosphorus 15
??? Sulfur 16
??? Chlorine 17
??? Argon 18
??? Potassium 19
??? Calcium 20
??? Scandium 21
??? Titanium 22
??? Vanadium 23
??? Chromium 24
??? Manganese 25
??? Iron 26
??? Cobalt 27
??? Nickel 28
??? Copper 29
??? Zinc 30
??? Gallium 31
??? Germanium 32
??? Arsenic 33
??? Selenium 34
??? Bromine 35
??? Krypton 36
??? Rubidium 37
??? Strontium 38
??? Yttrium 39
??? Zirconium 40
??? Niobium 41
??? Molybdenum 42
??? Technetium 43
??? Ruthenium 44
??? Rhodium 45
??? Palladium 46
??? Silver 47
??? Cadmium 48
??? Indium 49
??? Tin 50
??? Antimony 51
??? Tellurium 52
??? Iodine 53
??? Xenon 54
??? Cesium 55
??? Barium 56
??? Lanthanum 57
??? Cerium 58
??? Praseodymium 59
??? Neodymium 60
??? Promethium 61
??? Samarium 62
??? Europium 63
??? Gadolinium 64
??? Terbium 65
??? Dysprosium 66
??? Holmium 67
??? Erbium 68
??? Thulium 69
??? Ytterbium 70
??? Lutetium 71
??? Hafnium 72
??? Tantalum 73
??? Tungsten 74
??? Rhenium 75
??? Osmium 76
??? Iridium 77
??? Platinum 78
??? Gold 79
??? Mercury 80
??? Thallium 81
??? Lead 82
??? Bismuth 83
??? Polonium 84
??? Astatine 85
??? Radon 86
??? Francium 87
??? Radium 88
??? Actinium 89
??? Thorium 90
??? Protactinium 91
??? Uranium 92
??? Neptunium 93
??? Plutonium 94
??? Americium 95
??? Curium 96
??? Berkelium 97
??? Californium 98
??? Einsteinium 99
??? Fermium 100
??? Mendelevium 101
??? Nobelium 102
??? Lawrencium 103
??? Rutherfordium 104
??? Dubnium 105
??? Seaborgium 106
??? Bohrium 107
??? Hassium 108
??? Meitnerium 109
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