CESIUM

Atomic Number: 55
Mass Number: 132.90543
Electron Configuration: 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d¹⁰5p⁶6s¹
Crystal Structure: Body-Centered Cubic
Density: 1.87 g/cm³
Melting Point: 28^oC
First Ionization Energy: 376 kJ/mol
Atomic Radius: 265 pm
Ionic Radius: 167 pm
Standard Reduction Potential: -2.93 V (Cs⁺ + e^- = Cs)