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Date: 19-2-2019
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Nomenclature Based on Oxidation States
Many metals exhibit two or more oxidation states. This is particularly true of the transition metals, where cations with ONs of +2 and +3 are common, but also of the heavier main-group metals such as thallium (ONs +1 and +3), and tin and lead (ONs of +2 and +4).
The modern system of nomenclature uses ONs directly in naming compounds. Thus in FeO and Fe2O3, the ONs of Fe are +2 and +3, respectively, and we name these compounds iron(II) oxide and iron(III) oxide. Similarly, phosphorus(III) cholride is PCl3 and phosphorus(V) chloride is PCl5.
The traditional nomenclature for salts of such metals is to use the suffix -ic for the higher ON and –ous for the lower, often using the Latin name for the element, e.g., ferrous (Fe2+) and ferric (Fe3+), stannous (Sn2+) and stannic (Sn4+), chromous (Cr2+) and chromic (Cr3+).
Monatomic and polyatomic anions containing a single element are named with the -ide suffix, regardless of the formal oxidation state, e.g., chloride (Cl-), sulfide (S2-), and triiodide (I3-).
Both metals and nonmetals form oxoanions with the central atom in a variety of oxidation states, e.g., NO2- and NO3-, MnO42- and MnO4-. The traditional names reflect these differences by using the suffix - ate for the higher oxidation number and -ite for the lower. When more than two oxidation states are found, the highest uses the -ate suffix with the prefix per-, and the lowest uses the -ite suffix with the prefix hypo-. Some oxoanions with two central atoms linked by an oxygen use the di- prefix (indicating 2), others use the pyro- prefix, (indicating their origins as products obtained by heating—pyrolysis).
Some of the more common polyatomic anions are listed in Table 1.1.
Table 1.1. Common Anions Exhibiting Variable ON's
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اكتشاف تأثير صحي مزدوج لتلوث الهواء على البالغين في منتصف العمر
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زهور برية شائعة لتر ميم الأعصاب التالفة
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جمعيّة العميد وقسم الشؤون الفكريّة تدعوان الباحثين للمشاركة في الملتقى العلمي الوطني الأوّل
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الأمين العام المساعد لجامعة الدول العربية السابق: جناح جمعية العميد في معرض تونس ثمين بإصداراته
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المجمع العلمي يستأنف فعاليات محفل منابر النور في واسط
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برعاية العتبة العباسيّة المقدّسة فرقة العبّاس (عليه السلام) تُقيم معرضًا يوثّق انتصاراتها في قرية البشير بمحافظة كركوك
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