Atomic Radius (pm)
| Elements | van der Waals | Ionic | Covalent |
| H | 120-145 | 37 | |
| Li | 180 | 90 | 134 |
| C | 165-170 | 77 | |
| N | 155 | 75 | |
| O | 150 | 126 | 73 |
| F | 150-160 | 119 | 71 |
| Na | 230 | 116 | 154 |
| Cl | 170-190 | 167 | 99 |
| K | 280 | 152 | 196 |
| Br | 180-200 | 182 | 114 |
| Rb | 166 | ||
| I | 195-212 | 206 | 133 |
| Cs | 181 |
Energy Conversion Factors
| J | erg | eV | cm-1 | hartree | kcal/mol | |
| 1 J = | 1 | 107 | 6.2415x1018 | 5.0340x1022 | 2.2937x1017 | 1.4393x1020 |
| 1 erg = | 10-7 | 1 | 6.2415x1011 | 5.0340x1015 | 2.2937x1010 | 1.4393x1013 |
| 1 eV = | 1.6022x10-19 | 1.6022x10-12 | 1 | 8065.5 | 3.6749x10-2 | 23.060 |
| 1 cm-1 = | 1.9865x10-23 | 1.9865x10-16 | 1.2398x10-4 | 1 | 4.5563x10-6 | 2.8591x10-3 |
| 1 hartree = | 4.3598x10-18 | 4.3598x10-11 | 27.212 | 219474.6 | 1 | 627.51 |
| 1 kcal/mol = | 6.9478x10-21 | 6.9478x10-14 | 4.3364x10-2 | 349.75 | 1.5936x10-3 | 1 |