Arsenic sits at atomic number 33 on the periodic table, holding a notorious reputation as a potent toxic element yet playing subtle roles in industry and environmental chemistry.
Below is a structured reference that captures its core identity, key classifications, and measurable data for quick scanning and deeper exploration.
| Property | Value | Category | Notes |
|---|---|---|---|
| Atomic Number | 33 | Identification | Number of protons in the nucleus |
| Standard Atomic Weight | 74.92160 | Measurement | Relative isotopic mass weighted by natural abundance |
| Electron Configuration | [Ar] 3d¹⁰ 4s² 4p³ | Structure | Shows distribution of electrons in orbitals |
| Density | 5.73 g/cm³ (gray) | Physical | Measured near room temperature for most stable allotrope |
| Melting Point | 817 °C | Physical | Sublimation can occur near this range under atmospheric pressure |
| Classification | Post-transition metal / Metalloid | Chemical Behavior | Exhibits properties between metals and nonmetals |
Arsenic Chemical Properties and Behavior
Arsenic behaves as a metalloid due to its intermediate electrical conductivity and brittle solid form at standard conditions.
It forms stable compounds in multiple oxidation states, most commonly +3 and +5, which define much of its chemistry and toxicity.
In aqueous environments, arsenite and arsenate ions display different mobilities, influencing how arsenic moves through soil and groundwater systems.
Arsenic Sources, Uses, and Historical Context
Historically, arsenic compounds found roles in pigments, wood preservatives, and early pharmaceuticals, long before modern toxicology clarified the risks.
Today, controlled uses appear in semiconductor doping, glass manufacturing, and specialty alloys where its electronic and hardening effects are valuable.
Environmental arsenic often originates from natural mineral weathering, volcanic emissions, and legacy industrial discharges that continue to shape regional contamination patterns.
Arsenic Environmental Behavior and Mobility
In soils and sediments, arsenic can bind tightly to iron oxides, reducing mobility, yet under anaerobic conditions it may dissolve and travel with groundwater.
Microbial processes in wetlands and aquifers can transform inorganic arsenic into methylated forms, which sometimes exhibit higher toxicity and volatility.
Understanding these pathways is essential for assessing human exposure through drinking water, rice, and locally grown crops.
Arsenic Regulation, Risk Management, and Mitigation
Regulators set strict limits for arsenic in drinking water, often in the low microgram per liter range, to protect long-term public health.
Treatment technologies such as coagulation, adsorption, and membrane filtration are deployed to reduce arsenic concentrations below these thresholds.
Ongoing monitoring, source water protection, and community education form a multilayered approach to managing arsenic risks effectively.
Arsenic Periodic Table Context and Industrial Relevance
Its position in group 15 and period 4 makes arsenic a member of the pnictogens, sharing chemical relatives that influence its role in materials science and environmental chemistry.
Continued research on arsenic aims to refine its safe use in technology while minimizing ecological and public health burdens across diverse settings.
FAQ
Reader questions
How does arsenic behave differently in water compared to soil?
In soil, arsenic often attaches to minerals and organic matter, which can limit its movement, whereas in water it tends to dissolve and may travel far, especially as arsenate under oxidizing conditions.
What are the most common health effects linked to long-term arsenic exposure?
Chronic exposure is associated with skin lesions, cardiovascular disease, neurological impacts, and increased risk of certain cancers, particularly of the skin, bladder, and lungs.
Why does rice often contain higher arsenic levels than other grains?
Rice plants absorb arsenic more readily from flooded paddies because the anaerobic conditions convert inorganic arsenic into more soluble forms that accumulate in the grains.
How do water treatment systems remove arsenic from drinking water?
Effective methods include oxidation followed by adsorption on specialized media, membrane filtration, and tailored ion exchange approaches that reduce arsenic below regulatory limits.