Potassium: Element Overview

Basic Information

• Symbol: K
• Atomic Number: 19
• Atomic Weight: 39.0983 u
• Element Category: Alkali metal
• Group: 1
• Period: 4

Physical Properties

• Phase at Room Temperature: Solid
• Melting Point: 63.5 °C (146.3 °F)
• Boiling Point: 759 °C (1398 °F)
• Density: 0.89 g/cm³ at 20 °C
• Color: Silvery-white, often with a dull luster due to oxidation
• Crystal Structure: Body-centered cubic (bcc)

Chemical Properties

• Electronegativity: 0.82 (Pauling scale)
• Ionization Energies:
  • First: 418.8 kJ/mol
  • Second: 3052 kJ/mol
  • Third: 4420 kJ/mol
• Reactivity: Highly reactive, especially with water, producing hydrogen gas and heat, which can ignite the hydrogen.

Isotopes

• Stable Isotopes: Potassium has three naturally occurring isotopes: K-39, K-40, and K-41.
  • K-39: 93.2581%
  • K-40: 0.0117%
  • K-41: 6.7302%
• Radioactive Isotope: K-40 is radioactive and decays to both argon-40 and calcium-40.

Occurrence and Production

• Natural Abundance: Potassium is the 7th most abundant element in the Earth’s crust.
• Sources: Found in minerals such as feldspar, mica, and sylvite. Also abundant in seawater.
• Production: Commercially produced by the electrolysis of potassium hydroxide (KOH).

Uses and Applications

• Fertilizers: Potassium compounds, particularly potassium chloride (KCl), are extensively used in fertilizers to promote plant growth.
• Food Industry: Potassium is an essential nutrient for humans and is found in foods like bananas, potatoes, and spinach.
• Chemicals: Used in the production of potassium hydroxide (KOH), potassium nitrate (KNO₃), and potassium carbonate (K₂CO₃).
• Medical: Potassium is crucial for the proper function of cells, nerves, and muscles.
• Industrial: Used in the manufacturing of soaps, detergents, and glass.

Safety and Precautions

• Reactivity: Potassium is highly reactive, especially with water, and must be handled with care.
• Storage: Must be stored under mineral oil or in an inert atmosphere to prevent oxidation.
• Handling: Should be handled with gloves and eye protection. In case of contact with skin, it can cause severe burns.

Biological Role

• Essential Element: Potassium is vital for all living organisms.
• Cell Function: Regulates fluid balance, nerve signals, and muscle contractions.
• Energy Metabolism: Involved in various enzymatic processes.

Historical Background

• Discovery: Discovered in 1807 by Sir Humphry Davy through the electrolysis of potash (potassium carbonate).
• Naming: The name “potassium” comes from the word “potash,” referring to the extraction of potassium compounds from wood ash. The symbol “K” comes from the Latin word “kalium.”

Interesting Facts

• Soft Metal: Potassium is so soft that it can be cut with a knife.
• Flame Test: Potassium imparts a lilac or light purple color to a flame.
• Electrolyte: Potassium is one of the major electrolytes in the human body, crucial for maintaining proper physiological functions.

Summary

Potassium is an essential alkali metal known for its high reactivity and crucial role in biological systems. It is widely used in agriculture, the food industry, and various chemical processes. Discovered in the early 19th century, potassium is vital for plant and human health, playing a key role in cell function and metabolism. Its high reactivity necessitates careful handling and storage.

Questions and Answers about Potassium:

1. Q: What is the chemical symbol for Potassium?

   • A: K

2. Q: What is the atomic number of Potassium?

   • A: 19

3. Q: What type of element is Potassium?

   • A: Alkali metal

4. Q: What is the atomic weight of Potassium?

   • A: 39.0983 u

5. Q: What group is Potassium in?

   • A: Group 1

6. Q: What period is Potassium in?

   • A: Period 4

7. Q: What is the phase of Potassium at room temperature?

   • A: Solid

8. Q: What is the melting point of Potassium?

   • A: 63.5 °C (146.3 °F)

9. Q: What is the boiling point of Potassium?

   • A: 759 °C (1398 °F)

10. Q: What is the density of Potassium at 20 °C?

    • A: 0.89 g/cm³

11. Q: What is the color of Potassium metal?

    • A: Silvery-white

12. Q: What is the crystal structure of Potassium?

    • A: Body-centered cubic (bcc)

13. Q: What is the electronegativity of Potassium?

    • A: 0.82 (Pauling scale)

14. Q: What is the first ionization energy of Potassium?

    • A: 418.8 kJ/mol

15. Q: How many stable isotopes does Potassium have?

    • A: Three (K-39, K-40, K-41)

16. Q: What is the most abundant isotope of Potassium?

    • A: K-39

17. Q: How is Potassium commercially produced?

    • A: By the electrolysis of potassium hydroxide (KOH)

18. Q: What is the natural abundance of Potassium in the Earth’s crust?

    • A: 7th most abundant element

19. Q: What common mineral contains Potassium?

    • A: Feldspar

20. Q: What industry uses Potassium extensively for fertilizers?

    • A: Agriculture

21. Q: What is one use of Potassium in the food industry?

    • A: Essential nutrient in foods like bananas and potatoes

22. Q: What role does Potassium play in the chemical industry?

    • A: Production of potassium hydroxide (KOH) and potassium nitrate (KNO₃)

23. Q: Why is Potassium used in the medical field?

    • A: Crucial for proper cell, nerve, and muscle function

24. Q: What is the biological role of Potassium in the body?

    • A: Regulates fluid balance, nerve signals, and muscle contractions

25. Q: Who discovered Potassium?

    • A: Sir Humphry Davy

26. Q: In what year was Potassium discovered?

    • A: 1807

27. Q: What is the origin of the name “Potassium”?

    • A: From the word “potash,” derived from the extraction of potassium compounds from wood ash

28. Q: Why is the symbol for Potassium “K”?

    • A: From the Latin word “kalium”

29. Q: What property makes Potassium reactive with water?

    • A: Produces hydrogen gas and heat, which can ignite the hydrogen

30. Q: What health hazard is associated with Potassium metal?

    • A: Can cause severe burns if in contact with skin

31. Q: How should Potassium metal be stored?

    • A: Under mineral oil or in an inert atmosphere

32. Q: What is the second ionization energy of Potassium?

    • A: 3052 kJ/mol

33. Q: What is the third ionization energy of Potassium?

    • A: 4420 kJ/mol

34. Q: Is Potassium essential for plant health?

    • A: Yes, essential for plant growth

35. Q: What is the significance of Potassium in the energy metabolism?

    • A: Involved in various enzymatic processes

36. Q: What color does Potassium impart to a flame?

    • A: Lilac or light purple

37. Q: How does Potassium contribute to the manufacturing of glass?

    • A: Used in the production of certain types of glass

38. Q: What is Potassium’s role in the human diet?

    • A: Essential nutrient that supports various bodily functions

39. Q: How does Potassium affect nerve function?

    • A: Crucial for transmitting nerve signals

40. Q: What is the use of Potassium in soaps and detergents?

    • A: Used in the manufacturing process