Francium

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Francium

Atomic Mass	223
Electron Configuration	[Rn]7s1
Oxidation States	+1
Year Discovered	1939

Francium

Atomic Mass	223
Electron Configuration	[Rn]7s1
Oxidation States	+1
Year Discovered	1939

Identifiers

Element Name	Francium
Element Symbol	Fr
InChI	InChI=1S/Fr
InChIKey	KLMCZVJOEAUDNE-UHFFFAOYSA-N

Properties

Atomic Weight	223 223 [223]
Electron Configuration	[Rn]7s¹
Atomic Radius	Van der Waals Atomic Radius : 348 pm (Van der Waals) Covalent Atomic Radius : 260 pm (Covalent)
Oxidation States	+1 1
Ground Level	²S_1/2
Ionization Energy	3.9 eV 4.0727411 ± 0.0000011 eV
Electronegativity	Allen Scale Electronegativity : 0.67(Allen Scale)
Electron Affinity	0.47eV
Atomic Spectra	Lines Holdings Levels Holdings
Physical Description	Solid
Element Classification	Metal
Element Period Number	7
Element Group Number	1 - Alkali Metal
Melting Point	300 K (27°C or 81°F) 30°C
Boiling Point	680°C
Estimated Crustal Abundance	Not Applicable
Estimated Oceanic Abundance	Not Applicable

History

Francium was discovered by Marguerite Catherine Perey, a French chemist, in 1939 while analyzing actinium's decay sequence. Although considered a natural element, scientists estimate that there is no more than one ounce of francium in the earth's crust at one time. Since there is so little naturally occurring francium on earth, scientists must produce francium in order to study it. Francium can be produced by bombarding thorium with protons or by bombarding radium with neutrons. Francium's most stable isotope, francium-223, has a half-life of about 22 minutes. It decays into radium-223 through beta decay or into astatine-219 through alpha decay.

Discovered in 1939 by Mlle. Marguerite Perey of the Curie Institute, Paris. Francium, the heaviest known member of the alkali metals 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-three isotopes of francium are recognized. The longest lived 223Fr (Ac, K), a daughter of 227Ac, has a half-life of 22 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 resemble cesium.

Description

Francium was discovered in 1939 by Marguerite Perey, a physicist at the Curie Institute in Paris, France (Fig. IUPAC.87.1). ²²³Fr (with a half-life of 22 min) occurs naturally in uranium minerals as a result of actinium decay. However, it is estimated that no more than approximately 30 g of francium is present in the Earth’s crust at any time. Francium can be produced artificially for research by bombarding thorium with protons. Francium was named in honor of Perey’s home country, France [575], [576], [577]. Francium has no known isotopic applications outside of scientific research.

Fig. IUPAC.87.1: Francium was discovered in 1939 by Marguerite Perey, a physicist at the Radium Institute in Paris, France. Photo kindly provided by Musée Curie (Coll. ACJC), Institut Curie, Centre National de la Recherche Scientifique, Paris, France.

[575] E. Scerri. Nature Chem.1, 679 (2009).

[576] Science Education at Jefferson Lab. It’s Elemental – The Element Francium, Science Education at Jefferson Lab (2014), Feb. 25; http://education.jlab.org/itselemental/ele087.html.

[577] S. Soubrian. AIP History Newsletter36, (2004).

Compounds

See more information at the Francium compound page.

Element Forms

CID	Name	Formula	SMILES	Molecular Weight
6328145	francium	Fr	[Fr]	223.01973
10242604	francium-221	Fr	[221Fr]	221.01425
6337087	francium-223	Fr	[223Fr]	223.01973
6337674	francium-222	Fr	[222Fr]	222.01758
44154898	francium-220	Fr	[220Fr]	220.01233

Isotopes

Stable Isotope Count	0

Isotope Mass and Abundance

Isotope	Atomic Mass (uncertainty) [u]	Abundance (uncertainty)
²²³Fr	223.0197360(25)

Atomic Mass, Half Life, and Decay

Nuclide	Atomic Mass and Uncertainty [u]	Half Life and Uncertainty	Discovery Year	Decay Modes, Intensities and Uncertainties [%]
¹⁹⁷Fr	197.011008086 ± 0.000060584	2.3 ms ± 1.9	2013	α≈100%
¹⁹⁸Fr	198.010282081 ± 0.000033419	15 ms ± 3	2013	α≈100%
¹⁹⁸Fr^m	198.010282081 ± 0.000033419	1.1 ms ± 0.7	2013	α≈100%
¹⁹⁹Fr	199.007269384 ± 0.000014734	6.6 ms ± 2.2	1999	α≈100%; β⁺ ?
¹⁹⁹Fr^m	199.007269384 ± 0.000014734	6.5 ms ± 0.9	2013	α≈100%; β⁺ ?
¹⁹⁹Frⁿ	199.007269384 ± 0.000014734	2.2 ms ± 1.2	2013	α≈100%; β⁺ ?
²⁰⁰Fr	200.006584666 ± 0.000032769	47.5 ms ± 2.8	1995	α=100%; β⁺ ?; β⁺SF ?
²⁰⁰Fr^m	200.006584666 ± 0.000032769	190 ms ± 120	1996	α≈100%; IT ?
²⁰⁰Frⁿ	200.006584666 ± 0.000032769	790 ns ± 360	2014	IT ?
²⁰¹Fr	201.003852491 ± 0.000009747	62.8 ms ± 1.9	1980	α≈100%; β⁺ ?
²⁰¹Fr^m	201.003852491 ± 0.000009747	24 ms ± 6	2005	α=100%
²⁰¹Frⁿ	201.003852491 ± 0.000009747	720 ns ± 40	2014	IT=100%
²⁰²Fr	202.003329637 ± 0.000006476	372 ms ± 12	1980	α≈100%; β⁺ ?
²⁰²Fr^m	202.003329637 ± 0.000006476	286 ms ± 13	1980	α≈100%; IT=?; β⁺ ?
²⁰³Fr	203.000940867 ± 0.000006689	550 ms ± 10	1967	α≈100%; β⁺ ?
²⁰³Fr^m	203.000940867 ± 0.000006689	43 ms ± 4	2013	IT=80±0.4%; α=20±0.4%
²⁰³Frⁿ	203.000940867 ± 0.000006689	370 ns ± 50	2013	IT=100%
²⁰⁴Fr	204.000651972 ± 0.000026389	1.75 s ± 0.26	1964	α=96±0.2%; β⁺ ?
²⁰⁴Fr^m	204.000651972 ± 0.000026389	2.41 s ± 0.19	1967	α=90±0.2%; β⁺ ?
²⁰⁴Frⁿ	204.000651972 ± 0.000026389	1.65 s ± 0.15	1992	α=53±1%; IT=47±1%
²⁰⁵Fr	204.998593854 ± 0.000008399	3.90 s ± 0.07	1964	α=98.5±0.4%; β⁺=1.5±0.4%
²⁰⁵Fr^m	204.998593854 ± 0.000008399	80 ns ± 20	2012	IT=100%
²⁰⁵Frⁿ	204.998593854 ± 0.000008399	1.15 ms ± 0.04	2012	IT=100%
²⁰⁶Fr	205.998661441 ± 0.000029856	~16 s	1964	α=88.4±3.3%; β⁺=11.6±3.3%
²⁰⁶Fr^m	205.998661441 ± 0.000029856	~16 s	1964	α=84.7±1.5%; β⁺ ?; IT ?
²⁰⁶Frⁿ	205.998661441 ± 0.000029856	700 ms ± 100	1983	IT=?; α=13±0.2%
²⁰⁷Fr	206.996941450 ± 0.000018847	14.8 s ± 0.1	1964	α=95±0.2%; β⁺ ?
²⁰⁸Fr	207.997139082 ± 0.000012514	59.1 s ± 0.3	1964	α=89±0.3%; β⁺=11±0.3%
²⁰⁸Fr^m	207.997139082 ± 0.000012514	432 ns ± 11	2009	IT=100%
²⁰⁹Fr	208.995939701 ± 0.000012349	50.5 s ± 0.7	1964	α=89±0.3%; β⁺=11±0.3%
²⁰⁹Fr^m	208.995939701 ± 0.000012349	420 ns ± 18	2006	IT=100%
²¹⁰Fr	209.996410596 ± 0.000014407	3.18 m ± 0.06	1964	α=71±0.4%; β⁺ ?
²¹⁰Fr^m	209.996410596 ± 0.000014407	475 ns ± 6	2016	IT=100%
²¹¹Fr	210.995555189 ± 0.000012872	3.10 m ± 0.02	1964	α=87±0.3%; β⁺=13±0.3%
²¹¹Fr^m	210.995555189 ± 0.000012872	146 ns ± 14	1986	IT=100%
²¹¹Frⁿ	210.995555189 ± 0.000012872	124.5 ns ± 1.2	1986	IT=100%
²¹²Fr	211.996225420 ± 0.000009419	20.0 m ± 0.6	1950	β⁺=57±0.2%; α=43±0.2%
²¹²Fr^m	211.996225420 ± 0.000009419	31.9 us ± 0.7	1977	IT=100%
²¹²Frⁿ	211.996225420 ± 0.000009419	604 ns ± 28	1977	IT=100%
²¹²Fr^p	211.996225420 ± 0.000009419	312 ns ± 21	1986	IT=100%
²¹²Fr^q	211.996225420 ± 0.000009419	23.6 us ± 2.1	1990	IT=100%
²¹³Fr	212.996184410 ± 0.000005053	34.14 s ± 0.06	1964	α=99.44±0.5%; β⁺=0.56±0.5%
²¹³Fr^m	212.996184410 ± 0.000005053	505 ns ± 14	1971	IT=100%
²¹³Frⁿ	212.996184410 ± 0.000005053	238 ns ± 6	1971	IT=100%
²¹³Fr^p	212.996184410 ± 0.000005053	3.1 us ± 0.2	1989	IT=100%
²¹⁴Fr	213.998971193 ± 0.000009145	5.51 ms ± 0.13	1967	α=100%
²¹⁴Fr^m	213.998971193 ± 0.000009145	3.35 ms ± 0.05	1962	α=100%
²¹⁴Frⁿ	213.998971193 ± 0.000009145	103 ns ± 4	1993	IT=100%
²¹⁴Fr^p	213.998971193 ± 0.000009145	108 ns ± 7	1994	IT=100%
²¹⁵Fr	215.000341534 ± 0.000007585	90 ns ± 4	1970	α=100%
²¹⁶Fr	216.003189523 ± 0.00000448	700 ns ± 20	1970	α=100%; β⁺ ?
²¹⁶Fr^m	216.003189523 ± 0.00000448	850 ns ± 30	2007	α≈100%; β⁺ ?
²¹⁷Fr	217.004631980 ± 0.000007011	22 us ± 5	1968	α=100%
²¹⁸Fr	218.007578620 ± 0.000004546	1.4 ms ± 0.5	1949	α=100%
²¹⁸Fr^m	218.007578620 ± 0.000004546	21.9 ms ± 0.5	1982	α≈100%; IT ?
²¹⁹Fr	219.009250664 ± 0.00000738	22.5 ms ± 1.7	1948	α=100%
²²⁰Fr	220.012326789 ± 0.000004324	27.4 s ± 0.3	1948	α≈100%; β^-=0.35±0.5%
²²¹Fr	221.014253714 ± 0.000005245	4.801 m ± 0.005	1947	α≈100%; β^-=0.0048±1.5%; 14C=8.8e-11±1.1%
²²²Fr	222.017582615 ± 0.000008	14.2 m ± 0.3	1975	β^-=100%
²²³Fr	223.019734241 ± 0.000002073	22.00 m ± 0.07	1939	β^-≈100%; α=0.006%
²²⁴Fr	224.023348096 ± 0.000012	3.33 m ± 0.10	1969	β^-=100%
²²⁵Fr	225.025572466 ± 0.000012847	3.95 m ± 0.14	1969	β^-=100%
²²⁶Fr	226.029544512 ± 0.000006688	48.5 s ± 0.7	1969	β^-=100%
²²⁷Fr	227.031865413 ± 0.000006332	2.47 m ± 0.03	1972	β^-=100%
²²⁸Fr	228.035839433 ± 0.000007226	38 s ± 1	1972	β^-=100%
²²⁸Fr^m	228.035839433 ± 0.000007226	180 s ± 110	2008	IT ?; β^- ?
²²⁹Fr	229.038291443 ± 0.000005368	50.2 s ± 0.4	1975	β^-=100%
²³⁰Fr	230.042390787 ± 0.000007022	19.1 s ± 0.5	1987	β^-=100%
²³¹Fr	231.045175353 ± 0.0000083	17.6 s ± 0.6	1985	β^-=100%
²³²Fr	232.049461219 ± 0.000015	5.5 s ± 0.6	1990	β^-=100%; β^-SF ?
²³³Fr	233.052517833 ± 0.000021	900 ms ± 100	2010	β^-=100%; β^-n ?

Information Sources

Francium

View products including Francium ➡︎

Identifiers

Properties

History

Description

Users

Compounds

Element Forms

Isotopes

Isotope Mass and Abundance

Atomic Mass, Half Life, and Decay

Information Sources