Ta

Tantalum

Identification

CAS Number: 7440-25-7

Discovery Year: 1802

Discoverer: Anders Ekeberg

Discovery Location: Sweden

Properties

Atomic Mass: 180.94788 →Density: 16.4 g/cm³ →

Crust Abundance: 2 mg/kg

Crystal Structure: BCC

Atomic Dimensions

Atomic Radius: 145 pm →

Atomic Radius (Rahm): 258 pm

Covalent Radius: 170 pm →

Van der Waals Radius: 222.00000000000003 pm

Metallic Radius: 134 pm

Atomic Volume: 10.9 cm³/mol

Lattice Constant: 3.31 Å

Thermodynamics

Melting Point: 3269 K →Boiling Point: 5698 K →Specific Heat: 0.14 J/(g·K) →Thermal Conductivity: 57.5 W/(m·K) →Heat of Fusion: 24.7 kJ/mol →Heat of Vaporization: 758 kJ/mol →

Heat of Formation: 782 kJ/mol

Electronic Structure

Electron Config: [Xe] 4f14 5d3 6s2

Block: d

Period: 6 →Group: 5 →Electronegativity: 1.5 →Electron Affinity: 0.322 eV →

Oxidation States: +5

Abundance & Geochemistry

Crust Abundance: 2 mg/kg

Sea Abundance: 0.000002 mg/L

Geochemical Class: high field strength

Goldschmidt Class: litophile

About

Heavy blue-grey metallic transition element. Ta-181 is a stable isotope, and Ta-180 is a radioactive isotope, with a half-life in excess of 10^7 years. Used in surgery as it is unreactive. Forms a passive oxide layer in air. Identified in 1802 by Ekeberg and isolated in 1820 by Jons J. Berzelius.

Isotopes

Ta-181 181 99.99%

Ta-180 180 0.0120%