NEPTUNIUM, Np (93)

Neptunium is silvery, tarnishes when exposed to air and occurs in three allotropic forms and it normally exhibits five oxidation states, ranging from +3 to +7. It is radioactive, pyrophoric, and can accumulate in bones, which makes the handling of neptunium dangerous. The most stable isotope of neptunium, neptunium-237, is a by-product of nuclear reactors and plutonium production.

ELEMENT BRIEF

1940 by Edwin McMillan and Philip H. Abelson, USA.

DISCOVERY

From the name Neptune, the planet.

ETYMOLOGY

Neptunium

ELEMENT

Np

SYMBOL

93

ATOMIC NUMBER

7439-99-8

CAS NUMBER

ELEMENTAL SPECTRUM

Silver

ELEMENTAL COLOUR

-

REFRACTIVE INDEX

-

POISSON RATIO

11.567 cm³

MOLAR VOLUME

-

BRINELL HARDNESS

-

MOHS HARDNESS

-

VICKERS HARDNESS

-

SPEED OF SOUND

-

BULK MODULUS

-

SHEAR MODULUS

-

YOUNG MODULUS

ALLOTROPES

917.15 K, 644.00 °C

MELTING POINT

4,273.15 K, 4,000.00 °C

BOILING POINT

-

AUTOMATIC IGNITION

-

FLASHPOINT

-

CRITICAL TEMPERATURE

-

CRITICAL PRESSURE

6.000'000 W/(m K)

THERMAL CONDUCTIVITY

-

THERMAL EXPANSION

-

SPECIFIC HEAT

10.000 kJ/mol

HEAT FUSION

335.000 kJ/mol

HEAT VAPORISATION

-

HEAT COMBUSTION

-

CURIE POINT

-

NEEL POINT

-

ADIABATIC INDEX

Solid

PHASE

Conductor

ELECTRICAL TYPE

830.00k S/m

CONDUCTIVITY

1.20μ Ω.m

RESISTIVITY

-

SUPERCONDUCTING POINT

-

MAGNETIC TYPE

-

MASS SUSCEPTIBILITY

-

MOLAR SUSCEPTIBILITY

-

VOLUME SUSCEPTIBILITY

Actinide

CLASSIFICATION

236.547'371'8

ATOMIC WEIGHT

140 pm

ATOMIC RADIUS

171 pm

COVALENT RADIUS SINGLE BOND

136 pm

COVALENT RADIUS DOUBLE BOND

116 pm

COVALENT RADIUS TRIPLE BOND

221 pm

VAN DER WAALS RADIUS

[Rn]7s²5f⁴6d¹

ELECTRON CONFIGURATION

Orthorhombic, Primitive

CRYSTAL STRUCTURE

20.450'00 g/cm³

DENSITY AS SOLID

-

DENSITY AS LIQUID

-

DENSITY AS GAS

Pnma

SPACE GROUP NAME

62

SPACE GROUP NUMBER

π/2, π/2 π/2

LATTICE ANGLES

666.3, 472.3 488.7 pm

LATTICE CONSTANTS

6

VALENCE

1.36

ELECTRONEGATIVITY

-

ELECTRON AFFINITY

IONISATION ENERGY