Arsen / Arsenic (As)

Arsen je hemijski element sa simbolom As i atomskim brojem 33. U Periodnom Sistemu Elemenata je svrstan u 4. periodu i 5. glavnu grupu, odnosno u dušikovih grupu elemenata. Spada u polumetale. Agregatno stanje mu je čvrsto. Postoji u tri alotropske modifikacije:
    Sivi arsen- Nalazi se u prirodi, krut je i metalnog sjaja. Provodi električnu energiju.        
    Žuti arsen- Dobiva se  naglim hlađenjem  arsenovih para, mekan je poput voska i ne provodi električnu energiju.
    Amorfni arsen- Nastaje kondenzacijom arsenovih para na temperaturi od 100C° do 200C°. Tvrd je i crna sjaja.
Arsen i njegovi spojevi su otrovni i upotrebljavaju se kao insekticidi, kod izrade pesticida i pigmenta za boje.
Arsenovi spojevi su kumulativni otrovi. Zagrijavanjem na zraku, arsen izgara modrikastim plamenom, uz karakterističan miris po češnjaku, a nastaje i bijeli dim arsenova(III) oksida (As2O3). Upotrebljava se u medicini, industriji boja (bojadisalstvu) i za konzerviranje drva i kože.
Arsen je prvi otkrio Albertus Magnus u 1250.
Arsenovodik (AsH) je bezbojan, vrlo otrovan plin, mirisa po češnjaku.

Arsenic is a chemical element with the symbol As and atomic number 33. In the Periodic Table of the Elements, it is classified in the 4th period and the 5th main group, ie in the nitrogen group of elements. It belongs to the semi-metals. His physical state is solid. It exists in three allo tropical modifications:
    Gray arsenic- It is found in nature, it is rigid and has a metallic luster. It conducts electricity.
    Yellow arsenic- Obtained by the rapid cooling of arsenic vapors, is soft as wax and does not conduct electricity.
    Amorphous arsenic - Formed by condensation of arsenic vapor at a temperature of 100C ° to 200C °. It has a hard and black sheen.
Arsenic and its compounds are toxic and are used as insecticides, in the production of pesticides and pigments for paints.
Arsenic compounds are cumulative poisons. By heating in air, arsenic burns with a bluish flame, with a characteristic smell of garlic, and white smoke of arsenic (III) oxide (As2O3) is formed. It is used in medicine, the paint industry (painting) and for canning wood and leather.
Arsenic was first discovered by Albertus Magnus in 1250.
Arsenovodik (AsH) is a colorless, highly toxic gas, smelling of garlic