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87 Fr Francium 223

Francium

ALKALI METAL
Bohr Model: Electrons arranged in energy shells around the nucleus.

Francium is a chemical element with symbol Fr and atomic number 87. It used to be known as eka-caesium and actinium K. It is the second-least electronegative element, behind only caesium. Francium is a highly radioactive metal that decays into astatine, radium, and radon.

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Quick Facts

Atomic Number 87
Period 7
Group 1
Phase Solid
Appearance Unknown
About Alkali Metals

Alkali metals are highly reactive, soft, silver, and shiny metals found in Group 1. They readily lose their outermost electron to form positive ions (cations) with a charge of +1.

History

Discovered By Marguerite Perey
Named By Unknown

Physical Properties

Atomic Mass 223
Density 1.87 g/L
Molar Heat N/A J/(mol·K)
Phase Transition (Melting & Boiling Points)

Francium melts at 300 K and boils at 950 K.

Atomic Properties

Electron Config [Rn] 7s1
Electronegativity 0.79
Electron Affinity 46.89 kJ/mol
Ionization Energy 380 kJ/mol
Orbital Filling Diagram
This diagram visualizes electron configuration according to the Aufbau principle and Hund's rule. Boxes represent orbitals (s, p, d, f), while arrows indicate electrons with spin up or down. Electrons fill lower energy levels first and occupy orbitals singly before pairing.

Photograph

Image of Francium Source: Wikipedia

External Resources

Wikipedia PubChem Royal Society of Chemistry Periodic Videos (YouTube)

Study Guide

Atomic Number

The number of protons in the nucleus, which defines the element.

Atomic Mass

The average mass of an atom, including protons and neutrons.

Electronegativity

A measure of how strongly an atom attracts electrons in a bond.

Ionization Energy

The energy required to remove an electron from an atom.

Electron Config

The arrangement of electrons in the atom's energy shells.