|Name: arsenic||Group number: 15|
|Symbol: As||Group name: Pnictogen|
|Atomic number: 33||Period number: 4|
|Atomic weight: 74.92160 (2)||Block: p-block|
|CAS Registry ID: 7440-38-2||Voice: |
|Standard state: solid at 298 K||Colour: metallic grey|
|Classification: Semi-metallic||Availability: |
This sample is from The Elements Collection, an attractive and safely packaged collection of the 92 naturally occurring elements that is available for sale.
Elemental arsenic occurs in two solid modifications: yellow, and grey or metallic, with specific gravities of 1.97, and 5.73, respectively. The element is a steel grey, very brittle, crystalline, semimetallic (metalloid) solid. It tarnishes in air, and when heated rapidly oxidises to arsenous oxide which has a garlic odour.
Arsenic and its compounds are poisonous as any reader of "who-done-it" books knows. Upon heating arsenic and some minerals containing arsenic, it sublimes (transfers from the solid to the gaseous state, without passing through the liquid state).
IsolationHere is a brief summary of the isolation of arsenic.
It is not usually necessary to make arsenic in the laboratory as it is commercially available. Arsenic is found in nature in a number of minerals including realgar (As4S4), orpiment (As2S3), arsenolite (As2O3), and iron minerals such as arsenopyrite (FeAsS) and loellingite (FeAs2). Arsenic is made on an industrial scale by heating appropriate minerals in the absence of air. The arsenic is condensed out as a solid.
FeAsS (700°C) FeS + As(g) As(s)