Cesium

=Alkali Metals= There are five Alkali Metals; Potassium, Rubidium, Lithium, Sodium, and Cesium

Potassium is an element with a atomic number of 19 and an atomic mass of 39.098. Potassium is also essential in the human body, and we need to have a daily intake to maintain health. Potassium is a soft metal, and it can be easily cut with a regular knife.

Cesium (or Caesium) is an incredibly reactive element, with only 1 out of the 17 possible valence electrons. Cesium is liquid at about 83 degrees, almost room temperature. Its atomic number is 55, and its atomic mass is about 132.91. Like the other alkali metals, cesium reacts violently with water. Here's a video of cesium exploding in water

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