Sodium
Appearance | silvery white metallic
Standard atomic weight Ar, std(Na) | 22.989769 28(2)
Atomic number (Z) | 11
Group | group 1: H and alkali metals
Period | period 3
Block | s-block
Element category | Alkali metal
Electron configuration | [Ne] 3s1
Electrons per shell | 2, 8, 1
Phase at STP | solid
Melting point | 370.944 K ​(97.794 °C, ​208.029 °F)
Boiling point | 1156.090 K ​(882.940 °C, ​1621.292 °F)
Density (near r.t.) | 0.968 g/cm3
when liquid (at m.p.) | 0.927 g/cm3
Critical point | 2573 K, 35 MPa (extrapolated)
Heat of fusion | 2.60 kJ/mol
Heat of vaporization | 97.42 kJ/mol
Molar heat capacity | 28.230 J/(mol·K)
Oxidation states | −1, +1 (a strongly basic oxide)
Electronegativity | Pauling scale: 0.93
Ionization energies | 1st: 495.8 kJ/mol 2nd: 4562 kJ/mol 3rd: 6910.3 kJ/mol (more)
Atomic radius | empirical: 186 pm
Covalent radius | 166±9 pm
Van der Waals radius | 227 pm
Natural occurrence | primordial
Speed of sound thin rod | 3200 m/s (at 20 °C)
Thermal expansion | 71 µm/(m·K) (at 25 °C)
Thermal conductivity | 142 W/(m·K)
Electrical resistivity | 47.7 nΩ·m (at 20 °C)
Magnetic ordering | paramagnetic
Magnetic susceptibility | +16.0·10−6 cm3/mol (298 K)
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 Number | 7440-23-5
Discovery and first isolation | Humphry Davy (1807)