Chromium

(noun)

Chromium is a chemical element which has the symbol Cr and atomic number 24.

Related Terms

Examples of Chromium in the following topics:

  • Chromium

    • The most prominent example of toxic chromium is hexavalent chromium (Cr(VI)).
    • A large number of chromium(III) compounds are known.
    • Chromium(III) ions tend to form octahedral complexes.
    • Compounds of chromium(IV) (in the +4 oxidation state) are slightly more common than those of chromium(V).
    • Many chromium(II) compounds are known, including the water-stable chromium(II) chloride (CrCl2).

  • Titanium, Chromium, and Manganese

    • Weapons coated with chromium oxide were found with the Terracotta Army.
    • Nearly all of the chromium that is commercially extracted is done so from the only commercially viable ore, chromite, which is also known as iron chromium oxide (FeCr2O4).
    • Chromite is also the chief source for the chromium that is used in pigments.
    • Other applications of chromium compounds account for the remaining 15%.
    • Manganese is often used in pigments, again like chromium.

  • Oxidation Numbers of Metals in Coordination Compounds

    • Example 1: An oxide of chromium has the formula Cr2O3.
    • What is the oxidation number of each chromium ion?
    • Since the compound is neutral, the charge of each chromium must be +3 because 2(3)+3(-2) = 0.
    • What is the oxidation number of chromium?
    • Because the compound is neutral and 2(1)+(Cr)+4(-2)=0, chromium must have an oxidation number of +6.

  • Physical and Chemical Changes to Matter

    • For example, the color of the element chromium is determined by its oxidation state; a single chromium compound will only change color if it undergoes an oxidation or reduction reaction.

  • Occurrence of Metals

    • Metals that can be found as native deposits singly and/or in alloys include antimony, arsenic, bismuth, cadmium, chromium, cobalt, indium, iron, nickel, selenium, tantalum, tellurium, tin, titanium, and zinc.
    • The addition of silicon produces cast irons, while the addition of chromium, nickel and molybdenum to carbon steels (more than 10%) results in stainless steels.

  • Chemical Analysis

    • Those that form insoluble hydroxide complexes, such as iron, aluminum, and chromium.

  • Allyl and Crotyl Addition to Aldehydes and Ketones

    • To this end a variety of other metals, ranging from zinc, chromium and titanium to boron, silicon and tin, have been investigated.
    • The zinc, titanium and chromium reagents tend to undergo rapid E/Z interconversion, and either react with mixed diastereoselection or with a strong bias toward anti-selectivity.
    • Similarly, chromium (II) reagents generated in situ from (E or Z)-1-iodo-2-butene add to benzaldehyde with high selectivity favoring the anti-diastereomer.

  • Steelmaking and Refining

    • In this stage, impurities such as sulfur, phosphorus, and excess carbon are removed from the raw iron, and alloying elements such as manganese, nickel, chromium, and vanadium are added to produce the exact steel required.

  • Naming Coordination Compounds

  • Energy Consumption

    • The cost of electricity production from gas would increase by 30% if external costs such as damage to the environment and to human health, from the airborne particulate matter, nitrogen oxides, chromium VI, and arsenic emissions produced by these sources, were taken into account.