According to the electronic layer structure, physical properties of rare earth elements, symbiosis in minerals and different ionic radius, the 17 rare earth elements are usually divided into two groups:
Light rare earth elements: lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, and gadolinium.
Heavy rare earth elements: terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, yttrium.
The following table shows their physical properties| Atomic number | Elements | Atomic weight | Ionic radius (Å) | Density (g/cm³) | Meltability (℃) | Boiling Point (℃) | The melting point of the oxide (℃) | Specific resistance Ω×10cm6 | Ion magnetic moment (μB) | Thermal capture cross-section (barn) |
| 57 | La | 138.9 | 1.22 | 6.19 | 920±5 | 4230 | 2315 | 56.8 | 0 | 8.9 |
| 58 | Ce | 140.1 | 1.18 | 6.768 | 804±5 | 2930 | 1950 | 75.3 | 2.56 | 0.7 |
| 59 | Pr | 140.9 | 1.16 | 6.769 | 935±5 | 3020 | 2500 | 68 | 3.62 | 11.2 |
| 60 | Nd | 144.3 | 1.15 | 7.007 | 1024±5 | 3180 | 2270 | 64.3 | 3.68 | 46 |
| 61 | Pm | 147 | 1.14 | － | － | － | － | － | 2.83 | － |
| 62 | Sm | 150.4 | 1.13 | 7.504 | 1052±5 | 1630 | 2350 | 88 | 1.55～1.65 | 5500 |
| 63 | Eu | 152 | 1.13 | 5.166 | 826±10 | 1490 | 2050 | 81.3 | 3.40～3.50 | 4600 |
| 64 | Gd | 157.26 | 1.11 | 7.868 | 1350±20 | 2730 | 2350 | 140.5 | 7.94 | 46000 |
| 65 | Tb | 158.93 | 1.09 | 8.253 | 1336 | 2530 | 2387 | － | 9.7 | 44 |
| 66 | Dy | 162.51 | 1.07 | 8.565 | 1485±20 | 2330 | 2340 | 56 | 10.6 | 1100 |
| 67 | Ho | 164.94 | 1.05 | 8.799 | 1490 | 2330 | 2360 | 87 | 10.6 | 64 |
| 68 | Er | 167.27 | 1.04 | 9.058 | 1500～1550 | 2630 | 2355 | 107 | 9.6 | 166 |
| 69 | Tm | 168.94 | 1.04 | 9.318 | 1500～1600 | 2130 | 2400 | 79 | 7.6 | 118 |
| 70 | Yb | 173.04 | 1 | 6.959 | 824±5 | 1530 | 2346 | 27 | 4.5 | 36 |
| 71 | Lu | 174.99 | 0.99 | 9.849 | 1650～1750 | 1930 | 2400 | 79 | 0 | 108 |
| 21 | Sc | 44.97 | 0.83 | 2.995 | 1550～1600 | 2750 | － | － | － | 13 |
| 39 | Y | 88.92 | 1.06 | 4.472 | 1552 | 3030 | 2680 | － | － | 1.27 |
