With an atomic number 33, and atomic mass 74.92, arsenic is a notoriously poisonous metalloid with multiple allotropic forms. This write-up will tell you more…
Arsenic is a highly poisonous metallic element with three allotropic forms―yellow, black, and gray. Among these, gray is the most common one. It was discovered by the ancient Asians, Egyptians, Greeks, Romans, and Chinese, in ancient times. However, Albertus Magnus, a German Dominican, isolated Arsenic in 1250. Arsenic has been classified under metalloid elements, and can be found in groups 13,14, 15, 16, and 17 of the Mendeleev’s Periodic Table. The fact why arsenic is considered a metalloid element is because it bears the properties of both metals and non-metals.
Atomic Number (No. of protons or electrons): 33
Atomic Mass: 74.9216 amu
Density @ 293 K: 5.72 g/cm3
Electronic Configuration: [Ar]4s2 3d10 4p3
Melting Point: (the temperature below which a liquid turns into a solid) – 817.0 °C – 1090.15 °K
Boiling Point: (the temperature at which a liquid boils at sea level) – 613.0 °C – 886.15 °K
Specific Heat: (the heat required to raise the temperature of one gram of a substance one degree centigrade) (@20°C J/g mol) – 0.328
First Ionizing Energy (kJ/mol): 946.2
Ionic Radius: 46 (+5e) 222 (-3e)
Lattice Structure: Rhombohedral
Atomic Radius (pm): 139
► Arsenic has been attributed to be the ‘Kings of Poisons’, and its high toxicity level makes it a potent wood preservative against insects, bacteria, and fungi. For the same reason, it is also used in insecticides, poison, weed killers, etc.
► The 18th, 19th, and 20th centuries saw the application of arsenic in the form of medicines. Most common were arsphenamine and arsenic trioxide. The former medication was prescribed for syphilis and trypanosomiasis, while the latter one was found useful in treating cancer.
► Several solid state devices use arsenic as a doping agent. Lasers, which are employed for converting electricity into coherent light, also use arsenic in the form of gallium arsenide.
► Pyrotechny is defined as the craft of making fireworks, and this procedure uses arsenic for hardening and improving the sphericity (the roundness of a 3-dimensional object) of bullets, and in bronzing.
► Arsenic is found in its native state, and the most common mineral which bears it is known as arsenopyrite, also called mispickel (FeSAs). This mineral can be heated to derive sublime arsenic, leaving ferrous sufide. Although arsenopyrite is the main economical source of arsenic, there are also arsenides of metals such as silver, cobalt, and nickel. Apart from all these inorganic forms, the element can also be found in food, water, soil, and air.
Some common side effects of arsenic poisoning may include:
- Darkening of skin
- Poor appetite
- Increased sweating
- Mouth sores
- Trouble sleeping
- Weight loss
- Pale skin
- Post nasal drip
- Tightness in the chest
- Chest pain
- Rapid breathing
- Increased thirst
- Decreased urination
- Irregular pulse
- Dry eyes
- Skin lesions
- Sore throat
- Allergic reactions
- Loss of bowel or bladder control
- Spitting up of blood
- Sudden weight gain
- Swollen ankles, feet, or hands
The word ‘arsenic’ was borrowed from the Syriac word ‘zarniqa’. It was also borrowed from the word ‘Zarnikh’, which means ‘yellow orpiment’. It is related to the word ‘arsenikos’, which is a Greek word, and means ‘masculine’ or ‘potent’.