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:
Q: What is the chemical symbol for Arsenic?
- A: As
Q: What is the atomic number of Arsenic?
- A: 33
Q: What type of element is Arsenic?
- A: Metalloid
Q: What is the atomic weight of Arsenic?
- A: 74.921595 u
Q: What group is Arsenic in?
- A: Group 15
Q: What period is Arsenic in?
- A: Period 4
Q: What is the phase of Arsenic at room temperature?
- A: Solid
Q: What is the melting point of Arsenic?
- A: Sublimes at 615 °C (1137 °F) under standard atmospheric pressure
Q: What is the boiling point of Arsenic?
- A: 613 °C (1135 °F) (under pressure)
Q: What is the density of Arsenic at 20 °C?
- A: 5.776 g/cm³
Q: What is the color of Arsenic metal?
- A: Gray, metallic luster
Q: What is the crystal structure of Arsenic?
- A: Rhombohedral
Q: What is the electronegativity of Arsenic?
- A: 2.18 (Pauling scale)
Q: What is the first ionization energy of Arsenic?
- A: 947 kJ/mol
Q: How many stable isotopes does Arsenic have?
- A: One (As-75)
Q: What is the most common isotope of Arsenic?
- A: As-75
Q: How is Arsenic commercially produced?
- A: As a byproduct of mining and refining processes for other metals, especially copper and lead
Q: What is the natural abundance of Arsenic in the Earth’s crust?
- A: 53rd most abundant element
Q: What common minerals contain Arsenic?
- A: Arsenopyrite (FeAsS), realgar (As₄S₄), orpiment (As₂S₃)
Q: What industry uses Arsenic extensively for semiconductors?
- A: Electronics industry
Q: What is one use of Arsenic in agriculture?
- A: Historically used in pesticides and herbicides
Q: What role does Arsenic play in wood preservation?
- A: Used in chromated copper arsenate (CCA) to preserve wood
Q: Why is Arsenic used in glass production?
- A: Used to decolorize glass and in the production of special glass types
Q: What is the biological role of Arsenic in the body?
- A: Arsenic has no known essential biological role and is toxic
Q: Who discovered Arsenic?
- A: Known since ancient times, but first isolated by Albertus Magnus in 1250
Q: What is the origin of the name “Arsenic”?
- A: From the Greek word “arsenikon,” meaning potent
Q: What property makes Arsenic valuable in semiconductors?
- A: Its ability to form compounds like gallium arsenide (GaAs) used in electronics
Q: What health hazard is associated with Arsenic compounds?
- A: Highly toxic and carcinogenic
Q: How should Arsenic and its compounds be handled?
- A: With extreme care, using appropriate protective equipment
Q: What is the second ionization energy of Arsenic?
- A: 1798 kJ/mol
Q: What is the third ionization energy of Arsenic?
- A: 2735 kJ/mol
Q: Is Arsenic essential for plant health?
- A: Arsenic is not essential for plant health
Q: What is the significance of Arsenic in groundwater contamination?
- A: Naturally occurring arsenic can contaminate groundwater, posing health risks
Q: What is the role of Arsenic in medical treatments?
- A: Used in small doses in some medical treatments, including chemotherapy
Q: How does Arsenic benefit the glass industry?
- A: Used in the production of special glass types and to decolorize glass
Q: What is the use of Arsenic in alloys?
- A: Used in small quantities to improve the properties of lead and copper alloys
Q: How does Arsenic contribute to historical toxicology?
- A: Known as the “king of poisons” due to its potent toxicity and use in assassinations
Q: What is the environmental impact of Arsenic mining?
- A: Can cause environmental contamination and health hazards if not managed properly
Q: What color are Arsenic compounds typically?
- A: They can exhibit various colors, including yellow, red, and black, depending on the compound
Q: What is the role of Arsenic in geological exploration?
- A: Presence of arsenic can indicate the presence of gold deposits
