Arsenic

Type: Essential Mineral
Periodic Element: (As)
RDA: The average person’s intake is about 10–50 µg/day. 10 parts per billion (ppb) Acceptable amount in drinking water according to World Health Organization.
Importance- To Body:
Toxin at high levels.
Some evidence indicates that arsenic is an essential trace mineral in birds (chickens), and in mammals (rats, hamsters, and goats). However, the biological function is not known.
Distribution- In Body:
The organs of the body that are usually affected by arsenic poisoning are the lungs, skin, kidneys, and liver.
Excess Effects:
headaches, confusion, severe diarrhea, drowsiness developing into convulsions, leukonychia striata – Mees’s lines, or Aldrich-Mees’s lines, diarrhea, vomiting, vomiting blood, blood in the urine, cramping muscles, hair loss, stomach pain and more convulsions.
Arsenic has been linked to reproductive epigenetic changes, heritable changes in gene expression that occur without changes in DNA sequence. These include DNA methylation, histone modification, and RNA interference.
Deficiency Effects:
None listed
Sources Food:
Leafy Vegetables, Rice, Apple Juice, Grape Juice, Mushrooms, Seafood
Values about 1000 µg are not unusual following consumption of fish or mushrooms, but there is little danger in eating fish because this arsenic compound is nearly non-toxic.
Sources Environmental/Geographic:
Naturally occurring sources of human exposure include volcanic ash, weathering of minerals and ores, and mineralized groundwater. Arsenic is also found in food, water, soil, and air. Arsenic is absorbed by all plants, but is more concentrated in leafy vegetables, rice, apple and grape juice, and seafood. An additional route of exposure is inhalation of atmospheric gases and dusts.
Supplemental information:

Arsenic (Wikipedia)

For the poison commonly called arsenic, see Arsenic trioxide.

Arsenic,  ₃₃As

General properties
Pronunciation	/ˈɑːrsənɪk/ (AR-sən-ik) as an adjective: /ɑːrˈsɛnɪk/ (ar-SEN-ik)
Allotropes	grey (most common), yellow, black
Appearance	metallic grey
Standard atomic weight (Ar, standard)	7001749215950000000♠74.921595(6)
Arsenic in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson P ↑ As ↓ Sb germanium ← arsenic → selenium
Atomic number (Z)	33
Group	group 15 (pnictogens)
Period	period 4
Element category	metalloid
Block	p-block
Electron configuration	[Ar] 3d10 4s2 4p3
Electrons per shell	2, 8, 18, 5
Physical properties
Phase at STP	solid
Sublimation point	887 K ​(615 °C, ​1137 °F)
Density (near r.t.)	5.727 g/cm3
when liquid (at m.p.)	5.22 g/cm3
Triple point	1090 K, ​3628 kPa
Critical point	1673 K, ? MPa
Heat of fusion	grey: 24.44 kJ/mol
Heat of vaporization	34.76 kJ/mol (?)
Molar heat capacity	24.64 J/(mol·K)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 553 596 646 706 781 874
Atomic properties
Oxidation states	5, 4, 3, 2, 1, −1, −2, −3 ​(a mildly acidic oxide)
Electronegativity	Pauling scale: 2.18
Ionization energies	1st: 947.0 kJ/mol 2nd: 1798 kJ/mol 3rd: 2735 kJ/mol (more)
Atomic radius	empirical: 119 pm
Covalent radius	119±4 pm
Van der Waals radius	185 pm
Spectral lines
Miscellanea
Crystal structure	​rhombohedral
Thermal expansion	5.6 µm/(m·K) (at r.t.)
Thermal conductivity	50.2 W/(m·K)
Electrical resistivity	333 nΩ·m (at 20 °C)
Magnetic ordering	diamagnetic
Magnetic susceptibility	−5.5·10−6 cm3/mol
Young's modulus	8 GPa
Bulk modulus	22 GPa
Mohs hardness	3.5
Brinell hardness	1440 MPa
CAS Number	7440-38-2
History
Discovery	c. 800 CE
Main isotopes of arsenic
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct 73As syn 80.3 d ε 73Ge γ – 74As syn 17.8 d ε 74Ge β+ 74Ge γ – β− 74Se 75As 100% stable
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Arsenic is a chemical element with symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but only the gray form is important to industry.

The primary use of metallic arsenic is in alloys of lead (for example, in car batteries and ammunition). Arsenic is a common n-type dopant in semiconductor electronic devices, and the optoelectronic compound gallium arsenide is the second most commonly used semiconductor after doped silicon. Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides. These applications are declining, however.

A few species of bacteria are able to use arsenic compounds as respiratory metabolites. Trace quantities of arsenic are an essential dietary element in rats, hamsters, goats, chickens, and presumably many other species, including humans. However, arsenic poisoning occurs in multicellular life if quantities are larger than needed. Arsenic contamination of groundwater is a problem that affects millions of people across the world.

The United States' Environmental Protection Agency states that all forms of arsenic are a serious risk to human health. The United States' Agency for Toxic Substances and Disease Registry ranked arsenic as number 1 in its 2001 Priority List of Hazardous Substances at Superfund sites. Arsenic is classified as a Group-A carcinogen.