Element 33
Arsenic is a solid metalloid element with the atomic number 33 and a mass of 74.922. Traditionally, arsenic was used as a poison and green pigment, obviously being a dangerous combination. Wallpapers made of arsenic would eventually flake off and become toxic airborne particles. As a poison, arsenic was widely used in assasinations, due to it being easy to obtain, as well as being odorless and flavourless.
Arsenic metal is a light silvery colour. and It has a density of 5.7⁻³. When heated at 614 degrees, arsenic skips melting and sublimes almost instantly into a gas. However, under 28 atmospheres of pressure, arsenic can be liquified at 817 degrees. Arsenic reacts to heat and air to make arsenic trioxide, reacts with fluorine to make arsenic pentafluoride, and reacts with the rest of the halogens to make the arsenic trihalides. Arsenic dissolves in nitric acid to make arsenic acid and reacts with sulfuric acid to make arsenic trioxide.
Most arsenic is mined as minerals in China or Morocco. Industrially, arsenic is typically used as an alloying agent, while also being used in glass, colours, textiles, paper, metal adhesives, wood preservatives and ammunition. however, arsenic is found around the world contamianting groundwater, surpasing the WHO's reccomended amount in 70 countries.
Impure forms of arsenic were known as far back as Ancient egypt, however Albertus Magnus, a Germamn scientest, is usually credited as discovering Arsenic during the 1200s. He produced isolated Arsenic by heating together soap and a mineral that contained arsenic sulfide called "orpiment".
SOURCES
https://www.who.int/news-room/fact-sheets/detail/arsenic
https://www.lenntech.com/periodic/elements/as.htm
https://dirkncl.github.io/Ptable/data/reactions/33.htm
https://www.rsc.org/periodic-table/element/33/arsenic
https://epi.dph.ncdhhs.gov/oee/docs/ArsenicInfo.pdf
https://www.rcseng.ac.uk/library-and-publications/library/blog/arsenic-a-domestic-poison/
https://energyeducation.ca/encyclopedia/Arsenic