A

Arsenic

IUPAC: Arsenic

As Elements CAS 7440-38-2
Quick Reference
Formula / NotationAs
CAS Number7440-38-2
Molecular Weight74.92
Melting Point81.2
Boiling Point614.0
Density5.73
SolubilitySlightly soluble (1.7 mg/L at 25 C)
AppearanceSteel-grey crystalline metalloid (grey form); yellow amorphous form
Also Known AsAs, arsenic element
CategoryElements

What is Arsenic?

Arsenic is a metalloid, atomic number 33. A notorious poison since antiquity. Occurs naturally and from industrial contamination of groundwater. Also has industrial uses in semiconductors and wood preservatives. Groundwater arsenic contamination affects millions in South/SE Asia.

Formula & Notation

As

IUPAC Name: Arsenic

Other Names / Synonyms: As, arsenic element

Properties & Characteristics

Atomic number: 33. Atomic mass: 74.922 g/mol. Period 4, Group 15 (metalloid). Grey arsenic: mp 814 C (sublimes), density 5.73 g/cm3. Electronegativity: 2.18. Oxidation states: -3, +3, +5. One stable isotope: As-75. Allotropes: grey (metallic), yellow (molecular As4), black.

Physical Data

PropertyValue
Melting Point81.2
Boiling Point614.0
Density5.73
Molecular Weight74.92
SolubilitySlightly soluble (1.7 mg/L at 25 C)
AppearanceSteel-grey crystalline metalloid (grey form); yellow amorphous form

Uses & Applications

GaAs semiconductor (high-speed electronics, solar cells). Wood preservative (chromated copper arsenate - CCA). Pesticides and herbicides (historical). Lead shot hardener. Arsenic trioxide (As2O3) in cancer treatment (acute promyelocytic leukaemia). Glass decolourant.

Safety Information

Highly toxic - IARC Group 1 carcinogen. Inorganic arsenic: LD50 ~300 mg/kg. Chronic exposure causes skin lesions, peripheral neuropathy, liver damage, lung/bladder/skin cancer. Arsenic trioxide: very toxic (LD50 14.6 mg/kg). Arsine (AsH3): extremely toxic gas. Strict regulatory limits.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Arsenic
Formula As
CAS Number 7440-38-2
Molecular Weight 74.92
Category Elements
Synonyms As, arsenic element

Frequently Asked Questions

Arsenic is a metalloid, atomic number 33. A notorious poison since antiquity. Occurs naturally and from industrial contamination of groundwater. Also has industrial uses in semiconductors and wood preservatives. Groundwater arsenic contamination affects millions in South/SE Asia.

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