Caesium 

Robert Bunsen and Gustav Kirchhoff discovered caesium in 1860 through spectral analysis of mineral water. The element's name, "caesium," is derived from the Latin word "caesius," meaning sky blue, referencing the distinctive blue lines observed in its emission spectrum. This method of discovery, using spectral analysis, was groundbreaking at the time and helped identify caesium as a new alkali metal.

1.0What Is Caesium?

Caesium (Cs) is a chemical element with an atomic number of 55 and an atomic mass of 132.91 g/mol. It belongs to the alkali metals group (Group 1) in the periodic table and is found in Period 6, within the s-blockIt possesses a single electron in its outermost shell, which makes it highly reactive. Its electron configuration is [Xe] 6s¹. Caesium is a soft, silvery metallic solid at room temperature. As an alkali metal, it shares traits like low density and high reactivity, particularly with water and air.

2.0Occurrence and Extraction

Caesium is relatively scarce in the Earth's crust, where its concentration is only three parts per million. Primarily, it is present in uncommon minerals like pollucite (CsAlSiO3), which is present in some pegmatites of granite.

The most prevalent stable isotope of caesium is caesium-133. Nuclear fission also produces the radioactive isotope caesium-137 as a byproduct. Caesium-137 is widely utilized in a wide range of industrial and medical applications, including industrial gauges that measure material density or thickness and radiation therapy for cancer treatment.

Pollucite is mined and processed to yield calcium compounds, primarily calcium chloride, which can be reduced to yield pure calcium metal. This process is done to extract calcium.

3.0Physical Properties Of Caesium 

4.0Chemical Properties Of Caesium 

 Extremely reactive, particularly toward air and water.

• Reaction with Water: When calcium and water combine explosively, hydrogen gas (H₂) and calcium hydroxide (CsOH) are produced. The heat of this reaction can cause the compounds to burn.

2Cs + 2H₂O → 2CsOH + H₂↑

• Reaction with Air: Forms caesium oxide (CsO) through a rapid reaction with oxygen and moisture.
• State of Oxidation: Mainly +1 (Cs⁺).
• Compounds: Forms ionic compounds, including calcium bromide (CsBr), calcium chloride (CsCl), and calcium fluoride (CsF).

5.0Uses of Caesium

1. Atomic Clocks: Caesium-133 is used in atomic clocks, which are highly accurate and set the international standard for time (the SI second is defined by the caesium atom's radiation frequency).
2. Oil Drilling Fluids: Caesium formate is used in high-density oil and gas exploration drilling fluids.
3. Vacuum Tubes: Caesium is used as a getter in vacuum tubes, removing traces of oxygen and other gases.
4. Catalysts: Caesium is used as a catalyst in some chemical reactions.
5. Medical Applications: Caesium-137 is used in cancer treatment and as a tracer in radiology.
6. Photoelectric Cells: Caesium's photoelectric properties are utilised in devices like photomultiplier tubes.

6.0Safety and Health

Toxicity: While substances containing calcium are not very harmful, radioactive calcium (such as calcium-137) is extremely dangerous to your body because of its radiation.

Due to its high reactivity, calcium must be handled cautiously, particularly in water or moisture. It is typically stored in sealed containers to prevent reactions with air, often submerged in mineral oil or kept under an inert gas like argon.