Arsenic vs Antimony
Arsenic and Antimony 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 Antimony wears.
Side by side
| Property | Arsenic | Antimony |
|---|---|---|
| Symbol | As | Sb |
| Atomic number (Z) | 33 | 51 |
| Atomic mass | 74.922 u | 121.76 u |
| Category | Metalloid | Metalloid |
| Group | 15 | 15 |
| Period | 4 | 5 |
| Phase at room temp | solid | solid |
| Electron configuration | [Ar] 3d^10 4s^2 4p^3 | [Kr] 4d^10 5s^2 5p^3 |
| Valence electrons | 5 | 5 |
| Atomic radius | 114 pm | 133 pm |
| Electronegativity | 2.18 | 2.05 |
| First ionisation energy | 947 kJ/mol | 834 kJ/mol |
The verdicts
- Bigger atom: Antimony — the lower an element sits in its group, the more shells it wears.
- Greedy electron-taker: Arsenic — higher electronegativity means it pulls shared electrons harder.
- Heavier: Antimony — 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.