Arsenic: Element Overview

Basic Information

• Symbol: As
• Atomic Number: 33
• Atomic Weight: 74.921595 u
• Element Category: Metalloid
• Group: 15
• Period: 4

Physical Properties

• Phase at Room Temperature: Solid
• Melting Point: Sublimes at 615 °C (1137 °F) under standard atmospheric pressure
• Boiling Point: 613 °C (1135 °F) (under pressure)
• Density: 5.776 g/cm³ at 20 °C (gray arsenic)
• Color: Gray, metallic luster for the most stable form
• Crystal Structure: Rhombohedral

Chemical Properties

• Electronegativity: 2.18 (Pauling scale)
• Ionization Energies:
  • First: 947 kJ/mol
  • Second: 1798 kJ/mol
  • Third: 2735 kJ/mol
• Oxidation States: +5, +3, -3 (most common)
• Reactivity: Reacts with oxygen to form arsenic trioxide (As₂O₃) and with halogens to form arsenic halides.

Isotopes

• Stable Isotopes: Arsenic has one stable isotope: As-75.
• Radioisotopes: Several radioisotopes, including As-73 and As-74, which are used in medical and industrial applications.

Occurrence and Production

• Natural Abundance: Arsenic is the 53rd most abundant element in the Earth’s crust.
• Sources: Found in minerals such as arsenopyrite (FeAsS), realgar (As₄S₄), and orpiment (As₂S₃).
• Production: Primarily obtained as a byproduct of mining and refining processes for other metals, especially copper and lead.

Uses and Applications

• Semiconductors: Used in the production of gallium arsenide (GaAs) for integrated circuits and solar cells.
• Alloys: Used in small quantities to improve the properties of lead and copper alloys.
• Agriculture: Historically used in pesticides and herbicides, though usage has declined due to toxicity concerns.
• Wood Preservation: Arsenic compounds, such as chromated copper arsenate (CCA), are used to preserve wood.
• Medical: Used in small doses in some medical treatments, including chemotherapy for specific cancers.
• Glass Production: Arsenic trioxide is used to decolorize glass and in the production of special glass types.

Safety and Precautions

• Toxicity: Arsenic and its compounds are highly toxic and carcinogenic.
• Handling: Should be handled with extreme care, using appropriate protective equipment to avoid ingestion, inhalation, or skin contact.
• Regulations: Arsenic usage is heavily regulated due to its health hazards.

Biological Role

• Non-essential Element: Arsenic is not essential for life and is toxic to most living organisms.
• Health Effects: Chronic exposure can lead to arsenicosis, a condition characterized by skin lesions, cancer, and other health issues. Acute exposure can be fatal.

Historical Background

• Discovery and Use: Known since ancient times, arsenic compounds were used in medicines, cosmetics, and as poisons.
• Naming: The name “arsenic” comes from the Greek word “arsenikon,” meaning potent.

Interesting Facts

• Historical Poison: Arsenic was historically known as the “king of poisons” due to its potent toxicity and use in assassinations.
• Arsenic in Groundwater: Naturally occurring arsenic can contaminate groundwater, posing a significant health risk in many regions.
• Geological Indicator: Arsenic presence can indicate the presence of gold deposits, making it useful in mining exploration.

Summary

Arsenic is a versatile but highly toxic metalloid with applications in semiconductors, alloys, and wood preservation. It is primarily obtained as a byproduct of metal refining processes. Known since ancient times for its potent toxicity, arsenic continues to be a subject of significant health and safety regulations. While not essential for biological processes, arsenic’s unique properties make it valuable in various industrial and technological applications.

Questions and Answers about Arsenic:

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

   • A: As

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

   • A: 33

3. Q: What type of element is Arsenic?

   • A: Metalloid

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

   • A: 74.921595 u

5. Q: What group is Arsenic in?

   • A: Group 15

6. Q: What period is Arsenic in?

   • A: Period 4

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

   • A: Solid

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

   • A: Sublimes at 615 °C (1137 °F) under standard atmospheric pressure

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

   • A: 613 °C (1135 °F) (under pressure)

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

    • A: 5.776 g/cm³

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

    • A: Gray, metallic luster

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

    • A: Rhombohedral

13. Q: What is the electronegativity of Arsenic?

    • A: 2.18 (Pauling scale)

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

    • A: 947 kJ/mol

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

    • A: One (As-75)

16. Q: What is the most common isotope of Arsenic?

    • A: As-75

17. Q: How is Arsenic commercially produced?

    • A: As a byproduct of mining and refining processes for other metals, especially copper and lead

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

    • A: 53rd most abundant element

19. Q: What common minerals contain Arsenic?

    • A: Arsenopyrite (FeAsS), realgar (As₄S₄), orpiment (As₂S₃)

20. Q: What industry uses Arsenic extensively for semiconductors?

    • A: Electronics industry

21. Q: What is one use of Arsenic in agriculture?

    • A: Historically used in pesticides and herbicides

22. Q: What role does Arsenic play in wood preservation?

    • A: Used in chromated copper arsenate (CCA) to preserve wood

23. Q: Why is Arsenic used in glass production?

    • A: Used to decolorize glass and in the production of special glass types

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

    • A: Arsenic has no known essential biological role and is toxic

25. Q: Who discovered Arsenic?

    • A: Known since ancient times, but first isolated by Albertus Magnus in 1250

26. Q: What is the origin of the name “Arsenic”?

    • A: From the Greek word “arsenikon,” meaning potent

27. Q: What property makes Arsenic valuable in semiconductors?

    • A: Its ability to form compounds like gallium arsenide (GaAs) used in electronics

28. Q: What health hazard is associated with Arsenic compounds?

    • A: Highly toxic and carcinogenic

29. Q: How should Arsenic and its compounds be handled?

    • A: With extreme care, using appropriate protective equipment

30. Q: What is the second ionization energy of Arsenic?

    • A: 1798 kJ/mol

31. Q: What is the third ionization energy of Arsenic?

    • A: 2735 kJ/mol

32. Q: Is Arsenic essential for plant health?

    • A: Arsenic is not essential for plant health

33. Q: What is the significance of Arsenic in groundwater contamination?

    • A: Naturally occurring arsenic can contaminate groundwater, posing health risks

34. Q: What is the role of Arsenic in medical treatments?

    • A: Used in small doses in some medical treatments, including chemotherapy

35. Q: How does Arsenic benefit the glass industry?

    • A: Used in the production of special glass types and to decolorize glass

36. Q: What is the use of Arsenic in alloys?

    • A: Used in small quantities to improve the properties of lead and copper alloys

37. Q: How does Arsenic contribute to historical toxicology?

    • A: Known as the “king of poisons” due to its potent toxicity and use in assassinations

38. Q: What is the environmental impact of Arsenic mining?

    • A: Can cause environmental contamination and health hazards if not managed properly

39. Q: What color are Arsenic compounds typically?

    • A: They can exhibit various colors, including yellow, red, and black, depending on the compound

40. Q: What is the role of Arsenic in geological exploration?

    • A: Presence of arsenic can indicate the presence of gold deposits