Sodium facts for kids

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silvery white metallic

Spectral lines of sodium
General properties
Name, symbol, number Sodium, Na, 11
Pronunciation /ˈsdiəm/ SOH-dee-əm
Element category alkali metal
Group, period, block 1, 3, s
Standard atomic weight 22.98976928(2) g/mol
Electron configuration [Ne] 3s1
Electrons per shell 2,8,1 (Image)
Physical properties
Phase solid
Density (near r.t.) 0.968 g/cm3
Liquid density at m.p. 0.927 g/cm3
Melting point 370.87 K, 97.72 °C, 207.9 °F
Boiling point 1156 K, 883 °C, 1621 °F
Critical point (extrapolated)
2573 K, 35 MPa
Heat of fusion 2.60 kJ/mol
Heat of vaporization 97.42 kJ/mol
Specific heat capacity (25 °C) 28.230 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 554 617 697 802 946 1153
Atomic properties
Oxidation states +1, -1
(strongly basic oxide)
Electronegativity 0.93 (Pauling scale)
Ionization energies
1st: 495.8 kJ/mol
2nd: 4562 kJ/mol
3rd: 6910.3 kJ/mol
Atomic radius 186 pm
Covalent radius 166±9 pm
Van der Waals radius 227 pm
Crystal structure body-centered cubic
Magnetic ordering paramagnetic
Electrical resistivity (20 °C) 47.7 nΩ·m
Thermal conductivity (300 K) 142 W/(m·K)
Thermal expansion (25 °C) 71 µm/(m·K)
Speed of sound (thin rod) (20 °C) 3200 m/s
Young's modulus 10 GPa
Shear modulus 3.3 GPa
Bulk modulus 6.3 GPa
Mohs hardness 0.5
Brinell hardness 0.69 MPa
CAS registry number 7440-23-5
Most stable isotopes
Main article: Isotopes of Sodium
iso NA half-life DM DE (MeV) DP
22Na trace 2.602 y β+γ 0.5454 22Ne*
1.27453(2) 22Ne
ε→γ - 22Ne*
1.27453(2) 22Ne
β+ 1.8200 22Ne
23Na 100% 23Na is stable with 12 neutrons
Sodium pellets in a container

Sodium (symbol Na, from the Latin name natrium) is the chemical element number 11 in the periodic table of elements. It follows that its nucleus includes 11 protons, and 11 electrons orbit around it (according to the simplified model known as "Niels Bohr atom"). Even if a relatively large number of isotopes can be artificially produced, all decay in a short time. As a consequence all sodium found in nature (mainly in sea water) has the composition 11Na23, meaning that the nucleus includes 12 neutrons. The atomic mass of sodium is 22.9898; if it is rounded, it would be 23.


Sodium is a light, silver-coloured metal. Sodium is so soft that it can be easily cut with a knife. When it is cut, the surface will become white after a bit of time. This is because it reacts with air to form sodium hydroxide and sodium carbonate. Sodium is a little lighter than water; when it reacts with water it floats. This reaction is very fast. Hydrogen and sodium hydroxide are produced. The hydrogen may ignite. Since sodium melts at a low temperature, it melts when it reacts with water. It has one valence electron which is removed easily, making it highly reactive.

Compared with other alkali metals (metals in the first column of the periodic table), sodium is usually less reactive than potassium and more reactive than lithium.

Chemical compounds

These are chemical compounds that contain sodium ions. Sodium only exists in 1 oxidation state: +1.

Discovery and name

Sodium was discovered by Sir Humphrey Davy, an English scientist, back in 1807. He made it by the electrolysis of sodium hydroxide. It is named after soda, a name for sodium hydroxide or sodium carbonate.

Use as element

It is used in the preparation of organic compounds. It is also used in the street lights that are orange, and ultra violet lights.

Use as compounds

Sodium compounds are used in soaps, toothpaste, baking and antiacids. .

Occurrence and production

Sodium does not exist as an element in nature; its easily removed valence electron is too reactive. It exists as an ion in chemical compounds. Sodium ions are found in the ocean. It is also found as sodium chloride in the earth's crust, where it is mined.

Sodium is normally made by electrolysis of very hot sodium chloride that was melted.

Use in organisms

Sodium ion in the form of sodium chloride is needed in the human body, but large amounts of it cause problems, which is why one should not eat too much salt. Many organisms in the ocean depend on the proper concentration of ions in sea water to live.

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Sodium Facts for Kids. Kiddle Encyclopedia.