FRANCIUM

Introduction

Atomic Number: 87
Group: 1 or I A
Atomic Weight: 223
Period: 7
CAS Number: 7440-73-5

Classification

Chalcogen
Halogen
Noble Gas
Lanthanoid
Actinoid
Rare Earth Element
Platinum Group Metal
Transuranium
No Stable Isotopes
Solid
Liquid
Gas
Solid (Predicted)

Description • Uses/Function

Discovered in 1939 by Mlle. Marguerite Perey of the Curie Institute, Paris. Francium, the heaviest known member of the alkali metal series, occurs as a result of an alpha disintegration of actinium. It can also be made artificially by bombarding thorium with protons. While it occurs naturally in uranium minerals, there is probably less than an ounce of francium at any time in the total crust of the earth. It has the highest equivalent weight of any element, and is the most unstable of the first 101 elements of the periodic system. Thirty-five isotopes and isomers of francium are recognized. The longest lived 223Fr(Ac, K), a daughter of 227Ac, has a half-life of 21.8 min. This is the only isotope of francium occurring in nature. Because all known isotopes of francium are highly unstable, knowledge of the chemical properties of this element comes from radiochemical techniques. No weighable quantity of the element has been prepared or isolated. The chemical properties of francium most closely resemble cesium. 1

Physical Properties

Melting Point:2*  27 °C = 300.15 K = 80.6 °F
Boiling Point:2
Sublimation Point:2 
Triple Point:2 
Critical Point:2 
Density:   g/cm3

* - at 1 atm

Electron Configuration

Electron Configuration: [Rn] 7s1
Block: s
Highest Occupied Energy Level: 7
Valence Electrons: 1

Quantum Numbers:

n = 7
ℓ = 0
m = 0
ms = +½

Bonding

Electronegativity (Pauling scale):3 0.7
Electropositivity (Pauling scale): 3.3
Electron Affinity:4 0.46 eV
Oxidation States: +1

Ionization Potential   eV 5  kJ/mol  
Ionization Potential   eV 5  kJ/mol  
Ionization Potential   eV 5  kJ/mol  
1 4.0727    393.0

Thermochemistry

Specific Heat: 
Thermal Conductivity: 15 (W/m)/K, 27°C 6
Heat of Fusion: 
Heat of Vaporization: 
State of Matter Enthalpy of Formation (ΔHf°)7 Entropy (S°)7 Gibbs Free Energy (ΔGf°)7
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s) 0 0 22.50 94.14 0 0
(g) 17.40 72.8016 43.48 181.92032 11.15 46.6516

Isotopes

Nuclide Mass 8 Half-Life 8 Nuclear Spin 8 Binding Energy
199Fr 199.00726(4) 16(7) ms 1/2+# 1,538.13 MeV
200Fr 200.00657(8) 24(10) ms 3+# 1,546.20 MeV
201Fr 201.00386(8) 67(3) ms (9/2-) 1,554.27 MeV
202Fr 202.00337(5) 290(30) ms (3+) 1,562.34 MeV
203Fr 203.000925(17) 0.55(2) s (9/2-)# 1,570.41 MeV
204Fr 204.000653(26) 1.7(3) s (3+) 1,578.48 MeV
205Fr 204.998594(8) 3.80(3) s (9/2-) 1,595.87 MeV
206Fr 205.99867(3) ~16 s (2+,3+) 1,603.94 MeV
207Fr 206.99695(5) 14.8(1) s 9/2- 1,612.01 MeV
208Fr 207.99714(5) 59.1(3) s 7+ 1,620.08 MeV
209Fr 208.995954(16) 50.0(3) s 9/2- 1,628.15 MeV
210Fr 209.996408(24) 3.18(6) min 6+ 1,636.22 MeV
211Fr 210.995537(23) 3.10(2) min 9/2- 1,644.30 MeV
212Fr 211.996202(28) 20.0(6) min 5+ 1,652.37 MeV
213Fr 212.996189(8) 34.6(3) s 9/2- 1,660.44 MeV
214Fr 213.998971(9) 5.0(2) ms (1-) 1,668.51 MeV
215Fr 215.000341(8) 86(5) ns 9/2- 1,667.27 MeV
216Fr 216.003198(15) 0.70(2) μs (1-) 1,675.34 MeV
217Fr 217.004632(7) 16.8(19) μs 9/2- 1,683.41 MeV
218Fr 218.007578(5) 1.0(6) ms 1- 1,691.48 MeV
219Fr 219.009252(8) 20(2) ms 9/2- 1,699.55 MeV
220Fr 220.012327(4) 27.4(3) s 1+ 1,698.31 MeV
221Fr 221.014255(5) 4.9(2) min 5/2- 1,706.38 MeV
222Fr 222.017552(23) 14.2(3) min 2- 1,714.45 MeV
223Fr 223.0197359(26) 22.00(7) min 3/2(-) 1,722.52 MeV
224Fr 224.02325(5) 3.33(10) min 1- 1,721.28 MeV
225Fr 225.02557(3) 4.0(2) min 3/2- 1,729.35 MeV
226Fr 226.02939(11) 49(1) s 1- 1,737.42 MeV
227Fr 227.03184(11) 2.47(3) min 1/2+ 1,736.18 MeV
228Fr 228.03573(22)# 38(1) s 2- 1,744.25 MeV
229Fr 229.03845(4) 50.2(4) s (1/2+)# 1,752.32 MeV
230Fr 230.04251(48)# 19.1(5) s 1,751.08 MeV
231Fr 231.04544(50)# 17.6(6) s (1/2+)# 1,759.15 MeV
232Fr 232.04977(69)# 5(1) s 1,767.22 MeV
Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses. 8

Abundance

Safety Information


Material Safety Data Sheet - ACI Alloys, Inc.

For More Information

External Links:

Sources

(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:12.
(2) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(3) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 10:147-10:148.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(6) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(7) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(8) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(9) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).