Lithium vs Sodium
Lithium and Sodium sit in the same column of the periodic table — same family, one period apart — so almost every difference between them comes from one thing: the extra electron shell Sodium wears.
Side by side
| Property | Lithium | Sodium |
|---|---|---|
| Symbol | Li | Na |
| Atomic number (Z) | 3 | 11 |
| Atomic mass | 6.94 u | 22.990 u |
| Category | Alkali metal | Alkali metal |
| Group | 1 | 1 |
| Period | 2 | 3 |
| Phase at room temp | solid | solid |
| Electron configuration | [He] 2s^1 | [Ne] 3s^1 |
| Valence electrons | 1 | 1 |
| Atomic radius | 167 pm | 190 pm |
| Electronegativity | 0.98 | 0.93 |
| First ionisation energy | 520 kJ/mol | 496 kJ/mol |
The verdicts
- Bigger atom: Sodium — the lower an element sits in its group, the more shells it wears.
- Greedy electron-taker: Lithium — higher electronegativity means it pulls shared electrons harder.
- Heavier: Sodium — compare the atomic masses in the table above.
Want the visual version with bars for radius, electronegativity and ionisation energy? Open the interactive compare tool with this pair already loaded.