&lt;div class=&quot;track&quot;&gt;&lt;img alt=&quot;&quot; src=&quot;http://hits.guardian.co.uk/b/ss/guardiangu-feeds/1/H.22.2/26946?ns=guardian&amp;pageName=Arsenic+%5Bvideos%5D+%7C+%40GrrlScientist+%7C+Punctuated+Equilibrium+%3AArticle%3A1647590&amp;ch=Science&amp;c3=GU.co.uk&amp;c4=Periodic+table%2CChemistry+%28Science%29%2CScience&amp;c5=Unclassified%2CNot+commercially+useful&amp;c6=GrrlScientist&amp;c7=11-Oct-14&amp;c8=1647590&amp;c9=Article&amp;c10=Blogpost&amp;c11=Science&amp;c13=The+elements+%28series%29&amp;c25=Punctuated+Equilibrium+by+GrrlScientist&amp;c30=content&amp;h2=GU%2FScience%2Fblog%2FGrrlScientist&quot; width=&quot;1&quot; height=&quot;1&quot; /&gt;&lt;/div&gt;&lt;p class=&quot;standfirst&quot;&gt;What do wallpaper, chicken feed and Agatha Christie have in common?&lt;/p&gt;&lt;p&gt;Today, we&#039;re meeting yet another grey material, but unlike the other elements we&#039;ve learned about, this one often has a starring role in a number of Agatha Christie&#039;s novels. Arsenic is a metalloid, which means it has qualities of both metals and of nonmetals. Arsenic has the atomic symbol, As, and the atomic number 33. Arsenic is located directly below &lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/jun/03/1&quot;&gt;Phosphorus&lt;/a&gt; (which is an essential element for life) on the periodic table. &lt;/p&gt;&lt;p&gt; &lt;/p&gt;&lt;p&gt;Arsenic atoms can assume several different bonding patterns which are the basis of its allotropes, each of which has a different colour; metallic grey, yellow and black arsenic. Interestingly, using a hammer to bang on arsenide minerals releases a garlic-like odour, which is the result of toxic fumes created by the oxidation of arsenic to arsenic trioxide. &lt;/p&gt;&lt;p&gt;&lt;img align=&quot;right&quot; src=&quot;http://farm7.static.flickr.com/6110/6242496523_c25dfaa856_m.jpg&quot; width=&quot;100&quot; height=&quot;114&quot; /&gt;Arsenic has an interesting history. It was commonly used as a rodent poison in English households, and it was also a convenient murder weapon, particularly amongst the ruling classes. However, Victorian England used arsenic in a variety of ways; it was incorporated into wallpaper to prevent the growth of mould during the dark, damp English winters, it was used as the green colouring in paints, candies and candles, and as a preservative in lace. Unfortunately, the white powder was easily mistaken for sugar or flour and was incorporated into family dinners, resulting in numerous accidental poisonings, as we learn in the fascinating book, &lt;em&gt;The &lt;img align=&quot;right&quot; src=&quot;http://farm7.static.flickr.com/6154/6243122818_a12c97982b_t.jpg&quot; width=&quot;100&quot; height=&quot;99&quot; /&gt;Arsenic Century: How Victorian Britain was Poisoned at Home, Work, and Play&lt;/em&gt; by James C. Whorton [&lt;a href=&quot;http://www.amazon.co.uk/exec/obidos/ASIN/0199605998/livithescieli-21/&quot;&gt;Amazon UK&lt;/a&gt;; &lt;a href=&quot;http://www.amazon.com/exec/obidos/ASIN/0199605998/livingthescie-20/&quot;&gt;Amazon US&lt;/a&gt;]. Unfortunately, &quot;Mr Yuck&quot; did not appear for another 100 years. &lt;/p&gt;&lt;p&gt;Considering the toxicity of arsenic, it was very surprising when an &lt;a href=&quot;http://rrresearch.fieldofscience.com/2010/12/arsenic-associated-bacteria-nasas.html&quot;&gt;&lt;strong&gt;&lt;em&gt;extremely&lt;/em&gt; dubious bit of research&lt;/strong&gt;&lt;/a&gt; was published in the journal &lt;em&gt;&lt;a href=&quot;http://www.sciencemag.org/&quot;&gt;Science&lt;/a&gt;&lt;/em&gt; a few months ago about arsenic-associated bacterial life. Within a day or two, scientist Rosie Redfield wrote &lt;a href=&quot;http://rrresearch.fieldofscience.com/2010/12/arsenic-associated-bacteria-nasas.html&quot;&gt;a long and detailed analysis of the paper&#039;s methods and findings and published it on her blog&lt;/a&gt; -- that piece was later published as a letter in &lt;em&gt;Science&lt;/em&gt;. &lt;/p&gt;&lt;p&gt;Nevertheless, our favourite chemistry professor explains what that disputed research claimed to find: &lt;/p&gt;&lt;p&gt;Somewhat astonishingly, arsenic is used as an additive in commercial chicken feed in the United States after it was discovered that low concentrations act as a growth stimulant and prevent infection with the intestinal parasite, coccidia. But besides being a poison when consumed in large doses, chronic ingestion of low levels of arsenic is a health hazard too, potentially acting as a &lt;a href=&quot;http://motherjones.com/tom-philpott/2011/06/arsenic-chicken-fda-roxarsone-pfizer&quot;&gt;carcinogen in humans who consume farmed chickens or drink water contaminated with chicken faeces&lt;/a&gt;. &lt;/p&gt;&lt;p&gt;.. .. .. .. .. .. .. .. .. .. .. .. &lt;/p&gt;&lt;p&gt;Video journalist &lt;a href=&quot;http://periodicvideos.blogspot.com/&quot;&gt;Brady Haran&lt;/a&gt; is the man with the camera and the &lt;a href=&quot;http://www.nottingham.ac.uk/&quot;&gt;University of Nottingham&lt;/a&gt; is the place with the chemists. You can follow Brady on twitter @&lt;a href=&quot;http://twitter.com/#!/periodicvideos&quot;&gt;periodicvideos&lt;/a&gt; and the University of Nottingham on twitter @&lt;a href=&quot;http://twitter.com/#!/UniNottingham&quot;&gt;UniNottingham&lt;/a&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;You&#039;ve already met these elements:&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/oct/07/1&quot;&gt;Germanium&lt;/a&gt;: &lt;strong&gt;Ge&lt;/strong&gt;, atomic number &lt;strong&gt;32&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/sep/30/1&quot;&gt;Gallium&lt;/a&gt;: &lt;strong&gt;Ga&lt;/strong&gt;, atomic number &lt;strong&gt;31&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/sep/23/1&quot;&gt;Zinc&lt;/a&gt;: &lt;strong&gt;Zn&lt;/strong&gt;, atomic number &lt;strong&gt;30&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/sep/16/1&quot;&gt;Copper&lt;/a&gt;: &lt;strong&gt;Cu&lt;/strong&gt;, atomic number &lt;strong&gt;29&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/sep/09/1&quot;&gt;Nickel&lt;/a&gt;: &lt;strong&gt;Ni&lt;/strong&gt;, atomic number &lt;strong&gt;28&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/sep/02/1&quot;&gt;Cobalt&lt;/a&gt;: &lt;strong&gt;Co&lt;/strong&gt;, atomic number &lt;strong&gt;27&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/aug/26/1&quot;&gt;Iron&lt;/a&gt;:&lt;strong&gt; Fe&lt;/strong&gt;, atomic number &lt;strong&gt;26&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/aug/19/1&quot;&gt;Manganese&lt;/a&gt;: &lt;strong&gt;Mn&lt;/strong&gt;, atomic number &lt;strong&gt;25&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/aug/12/1&quot;&gt;Chromium&lt;/a&gt;: &lt;strong&gt;Cr&lt;/strong&gt;, atomic number &lt;strong&gt;24&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/aug/05/1&quot;&gt;Vanadium&lt;/a&gt;: &lt;strong&gt;V&lt;/strong&gt;, atomic number &lt;strong&gt;23&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/jul/29/1&quot;&gt;Titanium&lt;/a&gt;: &lt;strong&gt;Ti&lt;/strong&gt;, atomic number &lt;strong&gt;22&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/jul/15/1&quot;&gt;Scandium&lt;/a&gt;: &lt;strong&gt;Sc&lt;/strong&gt;, atomic number &lt;strong&gt;21&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/jul/08/1&quot;&gt;Calcium&lt;/a&gt;: &lt;strong&gt;Ca&lt;/strong&gt;, atomic number &lt;strong&gt;20&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/jul/01/1&quot;&gt;Potassium&lt;/a&gt;: &lt;strong&gt;K&lt;/strong&gt;, atomic number &lt;strong&gt;19&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/jun/24/1&quot;&gt;Argon&lt;/a&gt;: &lt;strong&gt;Ar&lt;/strong&gt;, atomic number &lt;strong&gt;18&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/jun/17/1&quot;&gt;Chlorine&lt;/a&gt;: &lt;strong&gt;Cl&lt;/strong&gt;, atomic number &lt;strong&gt;17&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/jun/10/2&quot;&gt;Sulfur&lt;/a&gt;: &lt;strong&gt;S&lt;/strong&gt;, atomic number &lt;strong&gt;16&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/jun/03/1&quot;&gt;Phosphorus&lt;/a&gt;: &lt;strong&gt;P&lt;/strong&gt;, atomic number &lt;strong&gt;15&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/may/27/chemistry-chemistry&quot;&gt;Silicon&lt;/a&gt;: &lt;strong&gt;Si&lt;/strong&gt;, atomic number &lt;strong&gt;14&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/may/20/1&quot;&gt;Aluminium&lt;/a&gt;: &lt;strong&gt;Al&lt;/strong&gt;, atomic number &lt;strong&gt;13&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/may/13/1&quot;&gt;Magnesium&lt;/a&gt;: &lt;strong&gt;Mg&lt;/strong&gt;, atomic number &lt;strong&gt;12&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/may/06/1&quot;&gt;Sodium&lt;/a&gt;: &lt;strong&gt;Na&lt;/strong&gt;, atomic number &lt;strong&gt;11&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/apr/15/1&quot;&gt;Neon&lt;/a&gt;: &lt;strong&gt;Ne&lt;/strong&gt;, atomic number &lt;strong&gt;10&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/apr/08/1&quot;&gt;Fluorine&lt;/a&gt;: &lt;strong&gt;F&lt;/strong&gt;, atomic number &lt;strong&gt;9&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/apr/01/1&quot;&gt;Oxygen&lt;/a&gt;: &lt;strong&gt;O&lt;/strong&gt;, atomic number &lt;strong&gt;8&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/mar/25/1&quot;&gt;Nitrogen&lt;/a&gt;: &lt;strong&gt;N&lt;/strong&gt;, atomic number &lt;strong&gt;7&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/mar/18/1&quot;&gt;Carbon&lt;/a&gt;: &lt;strong&gt;C&lt;/strong&gt;, atomic number &lt;strong&gt;6&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/mar/11/1&quot;&gt;Boron&lt;/a&gt;: &lt;strong&gt;B&lt;/strong&gt;, atomic number &lt;strong&gt;5&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/mar/04/1&quot;&gt;Beryllium&lt;/a&gt;: &lt;strong&gt;Be&lt;/strong&gt;, atomic number &lt;strong&gt;4&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/feb/18/1&quot;&gt;Lithium&lt;/a&gt;: &lt;strong&gt;Li&lt;/strong&gt;, atomic number &lt;strong&gt;3&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/feb/11/1&quot;&gt;Helium&lt;/a&gt;: &lt;strong&gt;He&lt;/strong&gt;, atomic number &lt;strong&gt;2&lt;/strong&gt;&lt;br /&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/punctuated-equilibrium/2011/feb/04/1&quot;&gt;Hydrogen&lt;/a&gt;: &lt;strong&gt;H&lt;/strong&gt;, atomic number &lt;strong&gt;1&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Here&#039;s a wonderful interactive &lt;a href=&quot;http://www.ptable.com/&quot;&gt;Periodic Table of the Elements&lt;/a&gt; that is just really &lt;em&gt;really&lt;/em&gt; fun to play with! &lt;/p&gt;&lt;p&gt;.. .. .. .. .. .. .. .. .. .. .. .. &lt;/p&gt;&lt;p&gt;twitter: @&lt;a href=&quot;http://twitter.com/#!/GrrlScientist&quot;&gt;GrrlScientist&lt;/a&gt; &lt;br /&gt;facebook: &lt;a href=&quot;http://www.facebook.com/grrlscientist&quot;&gt;grrlscientist&lt;/a&gt;&lt;br /&gt;email: &lt;a href=&quot;mailto:grrlscientist@gmail.com&quot;&gt;grrlscientist@gmail.com&lt;/a&gt;&lt;/p&gt;&lt;div class=&quot;related&quot; style=&quot;float: left; margin-right: 10px; margin-bottom: 10px;&quot;&gt;&lt;ul&gt;&lt;li&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/periodic-table&quot;&gt;Periodic Table&lt;/a&gt;&lt;/li&gt;&lt;li&gt;&lt;a href=&quot;http://www.guardian.co.uk/science/chemistry&quot;&gt;Chemistry&lt;/a&gt;&lt;/li&gt;&lt;/ul&gt;&lt;/div&gt;&lt;div class=&quot;author&quot;&gt;&lt;a href=&quot;http://www.guardian.co.uk/profile/grrlscientist&quot;&gt;GrrlScientist&lt;/a&gt;&lt;/div&gt;&lt;br/&gt;&lt;div class=&quot;terms&quot;&gt;&lt;a href=&quot;http://www.guardian.co.uk&quot;&gt;guardian.co.uk&lt;/a&gt; &amp;copy; 2011 Guardian News and Media Limited or its affiliated companies. 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