Francium

Francium is a chemical element with the symbol Fr and atomic number 87. It is the second-least electronegative element, behind only caesium, and is the second rarest naturally occurring element (after astatine). Francium is a highly radioactive metal that decays into astatine, radon, and polonium. It has no known uses.

Overview

English Name:

Francium

Latin Name:

Francium

Year Discovered:

1939

Discovered By:

Marguerite Perey

Group:

1

Period:

7

Electrons:

87

CAS Number:

7440-73-5

Cost Per 100 Grams:

$1 billion

Atomic Properties

Electronic Configuration:

[Rn] 7s¹

Ion Charge:

+1

Ionisation Energies:

392 kJ/mol

Atomic Radius (Empirical):

348 pm

Atomic Radius (Calculated):

348 pm

Covalent Radius:

223 pm

Van Der Waals Radius:

348 pm

Ionisation Potential of An Atom:

4.0 eV

Electrons Per Layer:

2, 8, 18, 32, 18, 8, 1

Atomic Multiplicities Of The Gas:

1

Atomic Weight:

223

Oxidation States

+1

Reactivity

Electron Affinity:

-46.9 kJ/mol

Valence:

1

Electronegativity:

0.7

Thermal Properties

Melting Point:

27 °C

Boiling Point:

677 °C

Critical Point:

Pressure: N/A

Temperature: N/A

Thermal Conductivity:

0.0023 W/(m·K)

Heat Capacity:

Specific: 0.028 J/(g·K)

Molar: 6.3 J/(mol·K)

Thermal Coefficient:

0.00004

Enthalpy:

Fusion: 2.1 kJ/mol

Vaporisation: 65 kJ/mol

Atomization: 393 kJ/mol

Curie Temperature:

N/A

Neel Temperature:

N/A

Superconductivity Point:

N/A

Physical and Chemical Properties

State of matter (25° C/ 77°F):

Solid

Density:

Solid: 2.8 g/cm³

Molar Volume (Vmol):

79.8 cm³/mol

Speed of Sound (Vs):

Not applicable

Hardness:

N/A

Bulk Modulus (K):

Not available

Shear Modulus (G):

N/A

Young's Modulus (E):

N/A

Color:

Silvery-white

Brinell Hardness (MPa):

N/A

Liquid Density (Kg/m^3):

1.87 kg/m³

Hardness of Mohs:

N/A

Refractive Index:

N/A

Vickers Hardness (MPa):

N/A

Crystal Structure:

Body-centered cubic (bcc)

Electromagnetic Properties

Electrical Type:

Conductor

Resistivity:

2.2 × 10^-7 Ω·m

Magnetic Type:

Paramagnetic

Superconductivity:

Not applicable

Volume Magnetic Susceptibility:

+1.0 × 10^-9

Mass Magnetic Susceptibility:

+3.6 × 10^-10 m³/kg

Molar Mass Susceptibility:

+8.0 × 10^-8 m³/mol

Electrical Conductivity:

4.5 × 10^6 S/m

Mass (γmass):

3.8 × 10-25 kg

Mass (γmol):

3.8 × 10-22 mol

Volume (γvol):

79.8 L

Grid Parameters

Crystal Structure:

Body-centered cubic (bcc)

Grid Parameters:

a = 7.8 Å

Attitude:

N/A

Debye Temperature:

N/A

Safety and Precautions

Signal Word:

Danger

Hazard Statements:

H300, H310, H330

Precautionary Statements:

P201, P202, P280, P308 + P313

RTECS Number:

Not available

Risk:

Flammability: Non-flammable
Health Risk: Highly toxic
Reactivity: Unstable
Specific Risk: Radioactive

Importance

Main sources:

Uranium ores

Main Usage:

No known uses

Nuclear Properties

Radioactive:

Yes

Isotopes:

Fr-223, Fr-221, Fr-220

Neutron Cross Sectional:

3.8 barns

Half Life (s):

21.8 minutes

Lifetime:

Stable

Prevalence

Universe:

0.00000000001%

Sun:

0.00000000001%

Oceans:

0.0000000000001%

Humans:

0.00000000000001%

Earth's Crust:

0.00000000001%

Meteorites:

0.00000000001%