Tecken	Fr
Atomnummer	87
Grupp	1 (Alkalimetaller)
Period	7
Block	s
Ämnesklass	Alkalimetall

Utseende	-
Färg	Silver

Antal protoner	87 p+
Antal neutroner	136 n0
Antal elektroner	87 e-

Från Wikipedia, den fria encyklopedinFrancium är ett radioaktivt grundämne med atomnummer 87 och kemiskt tecken Fr som tillhör gruppen alkalimetaller. Francium är starkt radioaktivt och mycket sällsynt i jordskorpan. Francium förekommer i uran- och toriummalm. Francium är det mest elektropositiva av alla grundämnen. Francium är dessutom så sällsynt att det brukar utelämnas när alkalimetallerna beskrivs. Man beräknar att det som allra mest finns 20 till 30 g francium i hela jordskorpan.

Fas vid STP	Fast
Densitet	1.87 g/cm3
Relativ atommassa	223 u

Smältpunkt	300 K 26.85 °C 80.33 °F
Kokpunkt	950 K 676.85 °C 1250.33 °F
Ångbildningsvärme	64 kJ/mol

Elektronegativitet (Paulingskalan)	0.79
Elektronaffinitet	46.89 kJ/mol
Oxidationstal	+1 (a strongly basic oxide)
Jonisationspotential	380 kJ/mol

Elektronkonfiguration Kortfattad konfiguration	[Rn] 7s1
Elektronkonfiguration Full konfiguration	1s2 2s2 2p6 3s2 3p6 3d10 4s24p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 7s1
Elektronkonfigurationsdiagram	1s2 2s2 2p6 3s2 3p6 3d10 4s24p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 7s1
Elektroner per skal	2, 8, 18, 32, 18, 8, 1
Valenselektroner	1
Valency-elektroner	1
Bohrs atommodell	Figur: Skaldiagram över Francium (Fr) atom.
Orbitaldiagram Warning: A non-numeric value encountered in /customers/a/d/1/periodictable.one/httpd.www/element.php on line 283 1s 2s 2p 3s 3p 3d 4s 4d 4f 5s 5p 5d 6s 6p 7s

Upptäckt och första isolation

Marguerite Perey (1939)

Upptäckten av francium Francium was discovered by Marguerite Perey in France (from which the element takes its name) in 1939. Prior to its discovery, it was referred to as eka-caesium or ekacaesium because of its conjectured existence below caesium in the periodic table. It was the last element discovered in nature, rather than synthesized, following hafnium and rhenium. Perey named the new isotope actinium-K (it is now referred to as francium-223) and in 1946, she proposed the name catium (Cm) for her newly discovered element, as she believed it to be the most electropositive cation of the elements. Irène Joliot-Curie, one of Perey's supervisors, opposed the name due to its connotation of cat rather than cation; furthermore, the symbol coincided with that which had since been assigned to curium. Perey then suggested francium, after France. This name was officially adopted by the International Union of Pure and Applied Chemistry (IUPAC) in 1949, becoming the second element after gallium to be named after France. It was assigned the symbol Fa, but this abbreviation was revised to the current Fr shortly thereafter.

CAS Number	7440-73-5
ChemSpider ID	4886484
EC number	-
PubChem CID Number	6328145