Rn#87 / 118Ra

87Fr[223]

Alkali Metalssolid at STPS-block

Francium

Group: 1•Period: 7•Standard Atomic Weight: [223] u

Open Full Periodic Table View Bohr Model

Why is Francium in this position?

Understanding the scientific rationale behind Francium's position in the periodic table:

Group Assignment

Group 1

Belongs to Group 1 because its outermost valence electron is 7s¹.

Period Assignment

Period 7

Belongs to Period 7 because its valence electron occupies the seventh principal shell (n=7).

Orbital Block

S-block

Belongs to the s-block because the differentiating electron enters the 7s orbital.

Chemical Category

Alkali Metals

Classified as an alkali metal due to its single valence electron and electropositive chemical nature.

Atomic Structure & Bohr Shell Model

Shell Distribution: [2, 8, 18, 32, 18, 8, 1]

Bohr Atomic Shell Model(2, 8, 18, 32, 18, 8, 1)

Hover or tap any shell orbit ring to inspect electron counts and 2n² capacities.

87 Protons (p⁺)136 Neutrons (n⁰)

Educational Note: This Niels Bohr planetary model visually illustrates principal quantum energy shells ($n=1, 2, 3\dots$) and electron counts. In modern quantum mechanics (Schrödinger model), electrons do not orbit in fixed circular planetary tracks, but exist as 3D probability clouds (orbitals: $s, p, d, f$) governed by the Heisenberg uncertainty principle.

Electron Shell Filling Breakdown

Shell K (n=1):2 / 2 electrons (100%)

Shell L (n=2):8 / 8 electrons (100%)

Shell M (n=3):18 / 18 electrons (100%)

Shell N (n=4):32 / 32 electrons (100%)

Shell O (n=5):18 / 50 electrons (36%)

Shell P (n=6):8 / 72 electrons (11%)

Shell Q (n=7):1 / 98 electrons (1%)

Aufbau Electron Configuration

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁶ 7s¹

Neutral ground state configuration. Valence electrons: 1.

Atomic & Quantum Properties

Electronegativity (Pauling)0.79 Pauling

1st Ionization Energy380 kJ/mol

Electron Affinity-44 kJ/mol

Atomic Radius (empirical)348 pm

Common Oxidation States+1

Crystal StructureBCC

Physical & Thermal Properties

Density at STP2.48 g/cm³ (predicted)

Melting Point27 °C (300 K)

Boiling Point677 °C (950 K)

Magnetic OrderingParamagnetic

Discovery Year1939

Discovered ByMarguerite Perey

Real-World Uses, Occurrence & Compounds

Major Industrial & Everyday Uses

Atomic physics precision laser trapping experiments testing the Standard Model and weak force parity violation
Nuclear structure research

Occurrence in Nature

Occurs naturally in minute traces in uranium and thorium ores as a branch decay product of Actinium-227.

Etymology & Name Origin

Named after France, the homeland of discoverer Marguerite Perey at the Curie Institute

Important Chemical Compounds

FrCl (Francium chloride, micro-scale trace chemistry)

Interesting Chemical Facts

• Marguerite Perey, a student of Marie Curie, discovered francium in Paris in 1939, naming it after her native France.
• At any given second, there is estimated to be no more than 20 to 30 grams of francium in the entire Earth's crust.
• The largest quantity of francium ever produced artificially in a laboratory was an optical trap containing approximately 300,000 francium atoms.

Safety & Handling Note

Intensely radioactive; extreme radiological danger even in microscopic quantities.