Element: Sodium
General data
| Element name | Sodium |
|---|---|
| Chemical symbol | Na |
| Atomic number Z | 11 |
| Year discovered | 1807 |
| Standard state (25°C) | Solid |
| Category | Alkali metal |
| Block | s |
| Atomic mass | 22.990 |
| CPK color | #AB5CF2 |
Physical properties
| Melting point | 370.95 K (97.80 °C) |
|---|---|
| Boiling point | 1156 K (883 °C) |
| Density | 0.97 g/cm³ |
Energy properties
| First ionization energy | 5.139 eV |
|---|---|
| Electron affinity | 0.548 eV |
Atomic structure
| Protons | 11 (Atomic number) |
|---|---|
| Neutrons (Na-23, most abundant isotope) | 12 |
| Electrons | 11 |
| Electron configuration | [Ne] 3s¹ |
| Oxidation states | +1 |
| Electronegativity (Pauling) | 0.93 |
| Atomic radius (van der Waals) | 227 pm |
Ionization energies - NIST ASD (11 states)
| State | Charge | Ioniz. energy (eV) | Type |
|---|---|---|---|
| Na I | 0+ | 5.13907696 ± 0.00000025 | measured |
| Na II | 1+ | 47.28636 ± 0.00025 | measured |
| Na III | 2+ | 71.62 ± 0.0012 | semi-empirical |
| Na IV | 3+ | 98.936 ± 0.012 | semi-empirical |
| Na V | 4+ | 138.404 ± 0.012 | measured |
| Na VI | 5+ | 172.23 ± 0.05 | semi-empirical |
| Na VII | 6+ | 208.504 ± 0.012 | semi-empirical |
| Na VIII | 7+ | 264.192 ± 0.022 | semi-empirical |
| Na IX | 8+ | 299.856 ± 0.007 | calculated |
| Na X | 9+ | 1465.0992 ± 0.0007 | calculated |
| Na XI | 10+ | 1648.702285 ± 0.000005 | calculated |
Value type as given by NIST ASD: measured - from evaluated experimental data; calculated - from ab initio calculations (mostly highly ionised atoms that have not been measured; for the simplest ones, e.g. H I, the calculation is more accurate than measurement); semi-empirical - from interpolation, extrapolation or another semi-empirical method.
Photos
Isotopes (20)
| A | N | Half-life | Decay |
|---|---|---|---|
| Na-17 | 6 | unknown | p |
| Na-18 | 7 | unbound (resonance) | p |
| Na-19 | 8 | unbound (resonance) | p |
| Na-20 | 9 | 448 ms | EC/β⁺ |
| Na-21 | 10 | 22.455 s | EC/β⁺ |
| Na-22 | 11 | 2.6019 a | EC/β⁺ |
| Na-23 | 12 | stable | - |
| Na-24 | 13 | 14.9578 h | β⁻ |
| Na-25 | 14 | 58.9 s | β⁻ |
| Na-26 | 15 | 1.0713 s | β⁻ |
| Na-27 | 16 | 301 ms | β⁻ |
| Na-28 | 17 | 34.6 ms | β⁻ |
| Na-29 | 18 | 43.2 ms | β⁻ |
| Na-30 | 19 | 44.8 ms | β⁻ |
| Na-31 | 20 | 17.0 ms | β⁻ |
| Na-32 | 21 | 13.2 ms | β⁻ |
| Na-33 | 22 | 8.2 ms | β⁻ |
| Na-34 | 23 | 5.5 ms | β⁻ |
| Na-35 | 24 | 2.4 ms | β⁻ |
| Na-37 | 26 | unknown | β⁻ |
Data sources
- PubChem Periodic Table API - Retrieved on 29 June 2026 - licence: CC0
- IUPAC CIAAW - Abridged Standard Atomic Weights 2024 - Table version: 2024 - licence: Public domain
- NNDC Wallet Cards 2023 - Data as of 15 October 2024 - licence: Public domain
- NIST Atomic Spectra Database (ASD) - Retrieved on 29 June 2026 - licence: © U.S. Secretary of Commerce
- Images of Elements - Retrieved on 29 June 2026 - licence: CC BY 3.0