55Cs132.9054520
Cesium
Alkali Metal
Solid at STP
Period 6Group 1Block SDiscovered 1860
[Xe]6s1
Caesium or cesium is a chemical element with symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a melting point of 28 °C (82 °F), which makes it one of only five elemental metals that are liquid at or near room temperature. Caesium is an alkali metal and has physical and chemical properties similar to those of rubidium and potassium.
📖 Read more on Wikipedia →Atomic Properties
| Atomic Number | 55 |
| Atomic Mass | 132.9054520 u |
| Electron Configuration | [Xe]6s1 |
| Oxidation States | +1 |
| Electronegativity | 0.79 (Pauling) |
| Atomic Radius | 343 pm |
| Ionization Energy | 3.894 eV |
| Electron Affinity | 0.472 eV |
| Block | S |
Physical Properties
| Appearance | silvery gold |
| Standard State | Solid |
| Melting Point | 301.59 K (28.4 °C) |
| Boiling Point | 944 K (670.9 °C) |
| Density | 1.93 g/cm³ |
| Molar Heat | 32.21 J/(mol·K) |
| CPK Color | #57178F |
Classification
| Category | Alkali Metal |
| Group Block | Alkali metal |
| Period | 6 |
| Group | 1 |
| Block | S |
Discovery
| Year Discovered | 1860 |
| Discovered By | Robert Bunsen |
| Electron Shells | 2, 8, 18, 18, 8, 1 |