87 - Francium alkali metal
Discovered by Marguerite Perey in 1939
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.
Periodic table
| Shell | Electrons | Orbitals |
|---|---|---|
| 1 | 2 | 2 in 1s |
| 2 | 8 | 2 in 2s + 6 in 2p |
| 3 | 18 | 2 in 3s + 6 in 3p + 10 in 3d |
| 4 | 32 | 2 in 4s + 6 in 4p + 10 in 4d + 14 in 4f |
| 5 | 18 | 2 in 5s + 6 in 5p + 10 in 5d |
| 6 | 8 | 2 in 6s + 6 in 6p |
| 7 | 1 | 1 in 7s |
Electron shells
223 u Atomic Mass
950 K Boiling Point
1 Group
1 Common Oxidation States
2.6 Å Covalent Radius
1.87 g/cm³ Density
46.9 kJ/mol Electron Affinity
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s1 Electron Configuration
[Rn] 7s1 Electron Configuration (semantic)
0.7 Electronegativity
87 Electrons
4.07 eV First Ionization Energy
380 kJ/mol Ionization Energies
300 K Melting Point
7 Mendeleev Number
7 Number of Shells
1 Electron Valency
136 Neutrons
87 Atomic Number
21 Number of Isotopes
1 Oxidation States
7 Period
Solid Phase
87 Protons