1. Harshini Wickremasinghe May 5, 2011 Bio 464

2. Physical/Chemical Properties Silvery, heavy, mobile, liquid phase Only liquid metal at room temp. Odorless Melting Point: -38.83 o C Boiling Point: 356.73 o C Density: 13.55g.cm -3 Low melting point due to unique electron configuration High surface tension Poor conductor of heat Good conductor of electricity

3. Chemical Properties Insoluble in water Does not react with oxygen in air very steadily When heated, reacts with oxygen in air to form mercury oxide At high temp., Hg vaporizes to form highly toxic fumes Extremely toxic and rarely found free in nature Often found as mineral cinnabar, HgS Cinnabar heated in air -> Hg vapor is distilled & cooled to form liquid Hg

4. Properties contd. 7 natural occurring isotopes; 202 Hg being the most abundant (29.86%) ~ 12 radioactive isotopes known Longest lived 194 Hg with half life of 444yrs 197 Hg & 203 Hg used to study brain and kidney Mercury exists in 3 oxidation states Organics (esp. CH3Hg(II)X) most toxic forms Airborne mercury is primarily inorganic mercury Mercury amalgams: used to extract precious metals like gold and silver; dental fillings

5. History fun facts Found in Egyptian tombs 1500 B.C Egyptians used in cosmetics, causing some facial deformities! Greeks: ointments Chinese: prolong life; good health

6. Uses/Applications Used in thermometers, barometers, electrical switches, mercury vapor lamps, fluorescent lamps, paints, fungicides/insecticides/antiseptics Dental amalgams, battery manufacturing

7. Hg in the aquatic environment Airborne mercury deposits into ground Rivers, streams and wetlands Sulfate-reducing bacteria buried in sediment transforms the inorganic Hg into CH 3 Hg Bioaccumulates in fish, aq. inverts. and mammals Conc. of Hg in organism increases with increasing trophic level in food chain Larger predatory game fish have higher levels of Hg Hg concentrates in muscle tissue of fish

8. Toxicity effects on humans Methyl mercury from fish consumption (highly toxic) or breathing vaporous mercury (bodies are more adapted to reducing toxic effects) Methyl mercury affects central nervous system and irreversible brain damage

9. 2 Biggest Hg poisonings “Mad Hatter” - during the industrial revolution, hat- makers used mercury nitrate to soften fur used as lining in hats. Toxic effected brains causing mental instability. Japan - 1952, chemical co. dumped Hg into Minamata harbor; residents of local fishing villages contaminated; 100s affected and 68 died