Ne
Mg
11Na22.990
Wikimedia Commons
Drop a piece of this metal into water and it bursts into flames. Sodium is so soft you can slice it with a butter knife. It floats on water, lighter than a cork. And it burns with a brilliant yellow flame. That same yellow glow lights up highways around the world through sodium vapor lamps.
But most sodium hides in plain sight — as table salt, NaCl. Humans have traded salt for thousands of years. Roman soldiers were partly paid in salt. Today, sodium works inside every cell of your body. Without it, nerves couldn't fire and muscles couldn't move.
Sodium is the sixth most abundant element in Earth's crust (2.3%). Its compounds are everywhere: baking soda, soap, glass, bleach. In industry, liquid sodium cools nuclear reactors — it conducts heat far better than water.
Scientists are now developing sodium-ion batteries as a cheaper alternative to lithium. Sodium is thousands of times more abundant than lithium on Earth. If the technology scales up, it could make electric vehicles and grid storage far more affordable.
11
Atomic Number
22.990u
Atomic Mass
[Ne] 3s1
e-config
0.93
Electroneg.
sodiumwhat is sodiumsodium propertiessodium usessodium elementNa
Properties
Physical Properties
371 K
98°C
Melting point
1156 K
883°C
Boiling point
0.97
g/cm³
Density
0.93
Pauling
Electronegativity
Atomic Structure
Group
1
Period
3
Block
S
Electron configuration
[Ne] 3s1
Bohr Model
K=2L=8M=1
Extended Properties
Structure
Crystal Structure
body-centered cubic (BCC)
Magnetic Ordering
paramagnetic
Mohs Hardness
0.5
Bulk Modulus
6.3GPa
Shear Modulus
3.3GPa
Poisson Ratio
0.32
Brinell Hardness
0.69MPa
Vickers Hardness
0.42MPa
Physical Properties
Thermal Conductivity
142W/(m·K)
Electrical Resistivity
47.7nΩ·m
Speed of Sound
3200m/s
Young's Modulus
10GPa
Specific Heat
1.228J/(g·K)
Heat of Fusion
2.6kJ/mol
Heat of Vaporization
97.42kJ/mol
Electron Affinity
52.8kJ/mol
Molar Volume
23.78cm³/mol
Atomic Properties
Atomic Radius
186pm
Covalent Radius
166pm
Van der Waals Radius
227pm
First Ionization Energy
495.8kJ/mol
Abundance
Earth Abundance
2.3%
Universe Abundance
0.002%
Ocean Abundance
1.08%
Human Body
0.14%
General
Atomic number11
Atomic mass22.9900u
Group1
Period3
BlockS
Standard stateSolid
Physical properties
Density0.968g/cm³
Melting point370.95 K (98°C)
Boiling point1156.00 K (883°C)
Speed of sound3200m/s
Young's modulus10GPa
Mohs hardness0.5
Molar volume23.78cm³/mol
Bulk modulus6.3GPa
Shear modulus3.3GPa
Poisson ratio0.32
Brinell hardness0.69MPa
Vickers hardness0.42MPa
Thermal properties
Thermal conductivity142W/(m·K)
Specific heat1.228J/(g·K)
Heat of fusion2.6kJ/mol
Heat of vaporization97.42kJ/mol
Atomic properties
Electron configuration[Ne] 3s1
Electronegativity0.93Pauling
Atomic radius186pm
Covalent radius166pm
Van der Waals radius227pm
Electromagnetic
First ionization energy495.8kJ/mol
Electron affinity52.8kJ/mol
Electrical resistivity47.7nΩ·m
Crystal structurebody-centered cubic (BCC)
Magnetic orderingparamagnetic
Abundance
Earth abundance2.3%
Universe abundance0.002%
Ocean abundance1.08%
Human body abundance0.14%
Numbers & Comparisons
0.97 g/cm³
lighter than water
Sodium floats in water — its density is below 1. One of only three metals that do this
0.5
Mohs hardness
Softer than a fingernail (2.5). You can easily cut sodium with an ordinary kitchen knife
97.8 °C
melting point
Melts near the boiling point of water. You could melt it in a pot on the stove
2.3%
of Earth's crust
Sixth most abundant element on Earth. More common than potassium or magnesium
Applications
🍽️
Food industry: table salt (NaCl), baking soda (NaHCO₃), and MSG — sodium compounds flavor and preserve food worldwide
💡
Street lighting: sodium vapor lamps produce bright yellow light and remain the most efficient option for highways
☢️
Nuclear energy: liquid sodium cools fast breeder reactors — it transfers heat more efficiently than water
⚙️
Metallurgy: sodium reduces titanium and zirconium from their chlorides (Kroll process) — no sodium means no titanium jets
🧪
Chemical industry: caustic soda (NaOH) is essential for making soap, paper, textiles, and aluminum
🩺
Medicine: saline solution (0.9% NaCl) is the first fluid given for dehydration — it closely matches blood plasma
🔍
Glass making: soda ash (Na₂CO₃) lowers the melting point of glass from 1700 °C to about 1000 °C
🔋
Energy storage: sodium-ion batteries are being developed as a cheap alternative to lithium for electric vehicles
Where to find in everyday life
Table salt
Sodium chloride (NaCl) is the most familiar sodium compound. Humans have mined salt for over 8,000 years
Baking soda
Sodium bicarbonate (NaHCO₃) makes dough rise, cleans stovetops, and even relieves heartburn
Bar soap
Every bar of soap is made using caustic soda (NaOH). Sodium is what makes soap solid
Street lamp
That yellow glow on evening streets comes from sodium lamps. They still light highways around the world
Saline drip
A 0.9% NaCl IV drip is the first thing given for dehydration. Its composition matches blood plasma
Safety & Warnings
Metallic sodium is extremely dangerous. It reacts violently with water, releasing hydrogen that immediately ignites. In moist air, sodium oxidizes within seconds. It must be stored under kerosene or mineral oil at all times. Never pour water on a sodium fire — it will explode. Use only dry sand or special powder extinguishers. Sodium hydroxide (NaOH) can burn through skin and eyes in seconds.
Dangerous
Fun Facts
Sodium floats on water and instantly catches fire. The metal skitters across the surface, hissing and burning yellow. The reaction 2Na + 2H₂O → 2NaOH + H₂ releases hydrogen, which ignites.
The word 'salary' comes from Latin 'sal' — salt. Roman legionaries received part of their pay in salt. Hence the phrase 'worth your salt.'
Sodium lamps emit yellow light at exactly 589 nm wavelength. They are the most efficient gas-discharge lamps — using 40% less energy than conventional streetlights.
Your body contains about 100 grams of sodium. The sodium-potassium pump in every cell fires 60 times per second. Without it, you couldn't think or move.
Sodium is twice as light as water — its density is just 0.97 g/cm³. It's one of only three metals that float in water (along with lithium and potassium).
Over 100,000 tons of metallic sodium are produced worldwide each year. Most goes into making titanium metal and industrial sodium compounds.