HÓA Nickel (Ni) là thành phần 28 và cùng với sắt (Fe) và cobalt (Co), các hình thức VIIIb nhóm quá trình chuyển đổi hàng loạt đầu tiên của bảng tuần hoàn. Trong dung dịch nước, niken thường hóa trị hai và tồn tại chủ yếu là các hexaquonickel [Ni (H 2O) 6] 2 ion, valences khác bao gồm 1, 0, 1, 3, 4 (1). Trong giải pháp, Ni 2 là 4 - hoặc 6coordinated và phổ biến nhất xảy ra trong cấu hình phẳng vuông và ít thường xuyên hơn trong cấu hình tứ diện hoặc tám mặt (2. | 11 Nickel Jessica E. Sutherland and Max Costa New York University School of Medicine Tuxedo New York 1. CHEMISTRY Nickel Ni is element 28 and along with iron Fe and cobalt Co forms the first transition series group VIIIb of the periodic table. In aqueous solutions nickel is most often divalent and exists primarily as the hexaquonickel Ni H2O 6 2 ion other valences include -1 0 1 3 and 4 1 . In solution Ni2 is 4- or 6-coordinated and most commonly occurs in square planar configuration and less often in tetrahedral or octahedral configurations 2 . Ni2 exhibits both hard and soft acid properties 3 and thus combines with nitrogen oxygen and sulfur-containing ligands in addition to donors from rows IV V VI and VII of the periodic table. Nickel also can combine with carbon monoxide at atmospheric pressure to form highly toxic nickel carbonyl Ni CO 4 . The acetate nitrate sulfate and halogen salts of nickel are all water soluble whereas the oxides sulfides carbonates phosphate and elemental forms of nickel are insoluble in water 4 . In biological systems Ni2 coordinates with water alone or with other soluble ligands. Nickel ions tend to be less soft than other toxic metal ions and hence are more likely to participate in ligand exchange reactions. Such reactions often govern the movement of nickel among different biological compartments. Copyright 2002 Marcel Dekker Inc. Important biological ligands for nickel are proteins containing the amino acids histidine and cysteine 5 . 2. NICKEL IN THE ENVIRONMENT Air Atmospheric nickel arises primarily from anthropogenic sources such as the burning of residual and fuel oil nickel metal refining municipal waste incineration steel production nickel alloy production and coal combustion 6 . These activities release approximately 56 million kg of nickel into the atmosphere per year 7 . Natural sources of atmospheric nickel are windblown dust volcanoes and wildfires and approximately million kg of nickel are released into the .
