1. Inhale Lately? Inhale Lately? (WebElements.com)

2. CHROMIUM CHROMIUM (WebElements.com)(periodictable.com) Atomic number: 24 Mass: 51.9961 Melting Point: 1860 °C (3380 °F) Boiling Point: 2670 °C (4838 °F) No taste or odor Physical: Chemical: Oxidation states Common: +2, +3, +6 Rare: +1, +4, +5 Cr III – Most stable insoluble in water Cr VI – prevails in seawater 100 – 1000x more toxic

3. Isotopes Isotopes *3 stable isotopes 52 Cr, 53 Cr, and 54 Cr *19 radioisotopes most stable being 50 Cr with half life > 1.8 x 10 17 years 51 Cr half life 27.7 days Rest have half life <24 hours majority < 1 minute

4. Uses Uses *Trace element for glucose metabolism not found as free metal in nature found as Chromite FeCr 2 O 4 & Crocoite PrCrO 4 Abundantly found in the Earth’s crust *Industrial uses: protective coating on metal, stainless steel, magnetic tapes, pigments in paints, cement, paper, rubber & floor coverings wood preservatives, tanning leather, fungicides, green color of emeralds, red color of rubies

5. How do they use it? How do they use it? Oil paints use Crocoite (Siberian red lead) – PrCrO 4 Commercially – alter Chromite ore Fe Cr 2 O 4 oxidation by air  Na 2 CrO 4 (can continue to 6+ state) extraction into water  Cr(III) oxide: Cr 2 O 3 Reacts with other elements Cr 2 O 3 + 2Al  2Cr + Al 2 O 3 2Cr 2 O 3 + 3Si  4Cr + 3 SiO 2

6. Chromium meet Environment Chromium meet Environment Introduced to air, soil and water *Manufacturing: chemical, pharmaceutical, metal finishes, paint dyes manufacturing releases hexavalent chromium (Cr+6) *Disposal of Products or Chemicals containing Cr *Burning of Fossil Fuels *Welding on stainless steel *Melting Cr metal Cr settles from air within 10 days sticks strongly to soil particles.

7. Toxicity of Cr Toxicity of Cr Cr III – moderate acute toxicity to aquatic life Cr III & Cr VI – high chronic toxicity to aquatic life Inhibits photosynthesis for aquatic plants reduces photo pigments, proteins, cysteine, ascorbic acid and non-protein thiol. In aquatic animals leads to metabolic issues, damage to liver, kidney and nerve tissue. Can cause lung cancer in some mammals. Toxicity defense: Increase superoxide dismutase, guaiacol, peroxidase and catalase Alter metabolic processes LC50: Fish – 7-400 ppm Daphnia – 001-0.26 ppm Algae – 0.032 – 6.4 ppm

8. References References Horcsik, ZT et al (2007) Effetcs of chromium on photosystem 2 in the unicellular green algae, Chlorella pyrenoidasa. Photosynthetica 45 (1): 65-69 Rai, V et al (2004) Effect of chromium accumulation on photosynthetic pigments, oxidative stress defense system, nitrate reduction, proline level and eugenol content of Ocimum tenuiflorum. Plant Science 167 (5): 1159-1169 Chaudhary, S, Van Horn, J.D. (2007) Breakdown Kinetics of the tri-chromium (III) oxo acetate cluster ( [Cr3O(OAc)6]+ with some ligands of biological interest. Journal of Inorganic Biochemistry 101 (2): 329-335 Winter, Mark (2008) University of Sheffield. Accessed April 23, 2008. <www. Webelements.com Department of the Environment, Water, Heritage and the Arts. (2008) Austrailian Government. Accessed April 23, 2008 Mathematica (2008) Wolfram research. Accessed April 23, 2008.

9. Questions? Questions? (webelements.com)