Sodium Element Properties
Complete reference for Sodium (Na, element 11): atomic data, electron configuration, isotopes, physical constants, and chemical behavior.
Sodium
Alkali Metal — Period 3, Group 1
Atomic Identity
Electron Configuration
One unpaired electron in 3s
Key Isotopes of Sodium
| Isotope | Symbol | Protons | Neutrons | Mass (u) | Natural Abundance | Stability |
|---|---|---|---|---|---|---|
| Sodium-22 | ²²Na | 11 | 11 | 21.9944364 | Radioactive |
Unstable
β⁺ decay, t½ = 2.6019 yr |
| Sodium-23 | ²³Na | 11 | 12 | 22.9897693 | 100% | Stable |
| Sodium-24 | ²⁴Na | 11 | 13 | 23.9909629 | Radioactive |
Unstable
β⁻ decay, t½ = 14.957 hr |
| Sodium-25 | ²⁵Na | 11 | 14 | 24.9899540 | Radioactive |
Unstable
β⁻ decay, t½ = 59.1 s |
Sodium-23 is the only stable isotope. Sodium-24 is used in medical and industrial tracing applications due to its convenient half-life.
Physical Properties
Chemical Properties
Ground State Quantum Numbers
Notable Emission Lines
Sodium produces an intense yellow-orange flame, dominated by the famous sodium D-line doublet at 589 nm — one of the most recognizable spectral signatures in chemistry.
Common Sodium Compounds
| Compound | Formula | Common Name | Key Uses |
|---|---|---|---|
| Sodium chloride | NaCl | Table salt | Food seasoning, food preservation, de-icing roads, chlorine production |
| Sodium hydroxide | NaOH | Lye / caustic soda | Soap making, paper production, drain cleaners, chemical manufacturing |
| Sodium bicarbonate | NaHCO₃ | Baking soda | Baking leavener, antacid, fire extinguisher, odor neutralizer |
| Sodium carbonate | Na₂CO₃ | Washing soda | Glass manufacturing, water softening, laundry detergent |
| Sodium hypochlorite | NaOCl | Bleach | Disinfection, water treatment, fabric whitening |
| Sodium nitrate | NaNO₃ | Chile saltpeter | Fertilizers, food preservative, explosives, glass making |
| Sodium sulfate | Na₂SO₄ | Glauber's salt | Detergents, glass manufacturing, textile dyeing |
| Sodium acetate | CH₃COONa | Hot ice | Food flavoring (salt and vinegar), heating pads, textile dyeing |
Key Facts About Sodium
Essential for Life
Sodium ions (Na⁺) are critical for nerve impulse transmission, muscle contraction, and regulating fluid balance in the body. Cells maintain a sodium-potassium gradient using the Na⁺/K⁺-ATPase pump, consuming about 30% of the body's resting energy.
Yellow Flame Test
Sodium produces the most intense and recognizable yellow-orange flame of any element, caused by the 589 nm D-line doublet. Even trace amounts of sodium overwhelm other colors, making it both a useful analytical tool and a challenge when testing other metals.
Sixth Most Abundant
Sodium is the sixth most abundant element in Earth's crust at about 2.6% by mass, found mainly in minerals such as halite (rock salt), albite, and natron. The oceans contain roughly 1.08 kg of sodium per liter of seawater.
Street Lighting
Low-pressure sodium (LPS) vapor lamps emit the characteristic monochromatic yellow 589 nm light and were widely used for street lighting because of their exceptional energy efficiency. High-pressure sodium (HPS) lamps produce a broader golden-white light still common in road lighting.
Discovered by Electrolysis
Humphry Davy isolated sodium in 1807 by passing electricity through molten sodium hydroxide, the first time a reactive metal was isolated this way. He named it sodium from the English word soda; Berzelius coined the symbol Na from natrium.
Softer than Most Metals
With a Mohs hardness of only 0.5, sodium can be cut with a kitchen knife. Freshly cut surfaces are shiny and silvery-white but quickly tarnish to dull gray as they react with oxygen and moisture in the air, forming sodium oxide and sodium hydroxide.
Summary
Complete reference for Sodium (Na, element 11): atomic data, electron configuration, isotopes, physical constants, and chemical behavior.
How it works
- Browse the atomic identity section for symbol, atomic number, and standard atomic weight.
- Check the electron configuration panel for orbital notation and quantum numbers.
- Review the isotopes table for sodium-23 and other isotopes including natural abundance.
- Consult the physical properties panel for melting point, density, and state at STP.
- Use the chemical properties section to understand alkali metal behavior and ionization energies.
- Explore common sodium compounds and their everyday applications.
Use cases
- Look up sodium constants for chemistry homework or exams.
- Verify atomic data when writing lab reports.
- Reference isotope data for nuclear chemistry or medical imaging research.
- Check thermodynamic constants for materials science or engineering.
- Teach or learn alkali metal properties using sodium as the primary example.
- Confirm electron configuration before writing molecular orbital diagrams.
- Research sodium compounds for pharmaceutical or industrial applications.
- Quick-reference ionization energy for electrochemistry or spectroscopy work.