Sodium
Soft silvery reactive element belonging to group 1 of the periodic table (alkali metals). It is highly reactive, oxidizing in air and reacting violently with water, forcing it to be kept under oil. It was first isolated by Humphrey Davy in 1807.
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Emission spectrum
Physical Propertiesmass · density · phase · crystal
Atomic Mass
22.9898Da
Density
0.9700g/cm³
Phase (STP)
Solid
Melting Point
370.9K
Boiling Point
1156.1K
Molar Heat
1.2280J/(mol·K)
Crystal Structure
BCC
Lattice Constant
4.230Å
Atomic Radiiatomic · covalent · van der Waals
Atomic (Empirical)
180.00pm
Covalent
155.00pm
Van der Waals
227.00pm
Electronic Propertieselectronegativity · ionization · affinity
Electron Configuration
[Ne] 3s
Electron Shells
2, 8, 1
Electronegativity
0.93Pauling
Electron Affinity
0.5kJ/mol
1st Ionization Energy
5.1kJ/mol
Oxidation States
-1, +1
Orbital DiagramAufbau · Hund's rule · Pauli exclusion
Full: 1s2 2s2 2p6 3s1Short: [Ne] 3s
Ionization Energies (11 known)
Emission Spectrumvisible range · characteristic spectral lines
Abundanceby mass
Log scale · ppm = parts per million by mass
Biological Role
Major electrolyte. Essential for nerve impulses, muscle contraction, and fluid balance.
Discovery
Discovered By
Sir Humphrey Davy
Named By
—
Year
1807
Nuclear Data
Known Isotopes
23
Stable Isotopes
4
Stable Mass Numbers
17, 23, 36, 38
Natural isotopic abundance (IUPAC recommended values)
Isotopes of Na23 known
| Nuclide | Z | N | Mass (AMU) | Half-life | Decay | Jπ | Abundance |
|---|---|---|---|---|---|---|---|
| 17Nastable | 11 | 6 | 17.037273 | Stable | p (1%) | 1/2+ | — |
| 18Na | 11 | 7 | 18.026879 | 1.30 zs | p | 1- | — |
| 19Na | 11 | 8 | 19.013880 | Unknown | p (1%) | 5/2+ | — |
| 23Nastable | 11 | 12 | 22.989769 | Stable | stable (1%) | 3/2+ | 10000.0000% |
| 36Nastable | 11 | 25 | 36.049279 | Stable | n | — | — |
| 37Na | 11 | 26 | 37.057042 | Unknown | β⁻, β⁻n, 2n | 3/2+ | — |
| 38Nastable | 11 | 27 | 38.066458 | Stable | n | — | — |
| 39Na | 11 | 28 | 39.075123 | Unknown | β⁻, β⁻n, 2n | 3/2+ | — |
Key Compoundscontaining Na
NaCl
Sodium Chloride
Common table salt with a face-centered cubic crystal lattice
NaHCO₃
Sodium Bicarbonate
Baking soda — a mild alkali that decomposes to Na₂CO₃, H₂O, and CO₂ when heated
NaOH
Sodium Hydroxide
Caustic soda — a strong base that fully dissociates in water
NaClO
Sodium Hypochlorite
The active ingredient in household bleach (typically 3–8% solution)
NaF
Sodium Fluoride
An ionic compound used to fluorinate drinking water (typically 0