According to the Aufbau process, the electrons fill the 4 s sublevel before beginning to fill the 3 d sublevel. However, the outermost s electrons are always the first to be removed in the process of forming transition metal cations.
This is the case for iron above. A half-filled d sublevel d 5 is particularly stable, which is the result of an iron atom losing a third electron. Iron II sulfate, FeSO 4 , has been known since ancient times as green vitriol and was used for centuries in the manufacture of inks. Some transition metals that have relatively few d electrons may attain a noble-gas electron configuration.
Scandium is an example. Most transition elements react slowly with cold water, or not at all. Iron reacts with water and oxygen at room temperature to form hydrated iron III oxide, or rust. For more information on rusting, visit the Using materials study guide. The group 1 elements react vigorously with the halogens. Some transition elements also react with halogens, for example:. Transition elements form ions with different charges.
For example:. These highest oxidation states are the most stable forms of scandium, titanium, and vanadium. However, it is not possible to continue to remove all of the valence electrons from metals as we continue through the series.
The elements of the second and third transition series generally are more stable in higher oxidation states than are the elements of the first series. In general, the atomic radius increases down a group, which leads to the ions of the second and third series being larger than are those in the first series.
Removing electrons from orbitals that are located farther from the nucleus is easier than removing electrons close to the nucleus. Which is the strongest oxidizing agent in acidic solution: dichromate ion, which contains chromium VI , permanganate ion, which contains manganese VII , or titanium dioxide, which contains titanium IV?
First, we need to look up the reduction half reactions Table P1 for each oxide in the specified oxidation state:. A larger reduction potential means that it is easier to reduce the reactant. Permanganate, with the largest reduction potential, is the strongest oxidizer under these conditions. Dichromate is next, followed by titanium dioxide as the weakest oxidizing agent the hardest to reduce of this set. You will need to use the standard reduction potentials from Table P1.
Ancient civilizations knew about iron, copper, silver, and gold. The time periods in human history known as the Bronze Age and Iron Age mark the advancements in which societies learned to isolate certain metals and use them to make tools and goods.
Iron, on the other hand, occurs on earth almost exclusively in oxidized forms, such as rust Fe 2 O 3. The earliest known iron implements were made from iron meteorites. Surviving iron artifacts dating from approximately to BC are rare, but all known examples contain specific alloys of iron and nickel that occur only in extraterrestrial objects, not on earth.
It took thousands of years of technological advances before civilizations developed iron smelting , the ability to extract a pure element from its naturally occurring ores and for iron tools to become common.
Generally, the transition elements are extracted from minerals found in a variety of ores. However, the ease of their recovery varies widely, depending on the concentration of the element in the ore, the identity of the other elements present, and the difficulty of reducing the element to the free metal.
In general, it is not difficult to reduce ions of the d -block elements to the free element. Carbon is a sufficiently strong reducing agent in most cases. However, like the ions of the more active main group metals, ions of the f -block elements must be isolated by electrolysis or by reduction with an active metal such as calcium. We shall discuss the processes used for the isolation of iron, copper, and silver because these three processes illustrate the principal means of isolating most of the d -block metals.
In general, each of these processes involves three principal steps: preliminary treatment, smelting, and refining. The early application of iron to the manufacture of tools and weapons was possible because of the wide distribution of iron ores and the ease with which iron compounds in the ores could be reduced by carbon.
For a long time, charcoal was the form of carbon used in the reduction process. The production and use of iron became much more widespread about , when coke was introduced as the reducing agent. Coke is a form of carbon formed by heating coal in the absence of air to remove impurities. The first step in the metallurgy of iron is usually roasting the ore heating the ore in air to remove water, decomposing carbonates into oxides, and converting sulfides into oxides.
Molten iron and slag are withdrawn at the bottom. The entire stock in a furnace may weigh several hundred tons. Near the bottom of a furnace are nozzles through which preheated air is blown into the furnace. As soon as the air enters, the coke in the region of the nozzles is oxidized to carbon dioxide with the liberation of a great deal of heat.
The hot carbon dioxide passes upward through the overlying layer of white-hot coke, where it is reduced to carbon monoxide:. The carbon monoxide serves as the reducing agent in the upper regions of the furnace. The iron oxides are reduced in the upper region of the furnace.
In the middle region, limestone calcium carbonate decomposes, and the resulting calcium oxide combines with silica and silicates in the ore to form slag. The slag is mostly calcium silicate and contains most of the commercially unimportant components of the ore:. Just below the middle of the furnace, the temperature is high enough to melt both the iron and the slag.
They collect in layers at the bottom of the furnace; the less dense slag floats on the iron and protects it from oxidation. Several times a day, the slag and molten iron are withdrawn from the furnace. Much of the iron produced is refined and converted into steel. Steel is made from iron by removing impurities and adding substances such as manganese, chromium, nickel, tungsten, molybdenum, and vanadium to produce alloys with properties that make the material suitable for specific uses.
Most steels also contain small but definite percentages of carbon 0. However, a large part of the carbon contained in iron must be removed in the manufacture of steel; otherwise, the excess carbon would make the iron brittle.
The most important ores of copper contain copper sulfides such as covellite, CuS , although copper oxides such as tenorite, CuO and copper hydroxycarbonates [such as malachite, Cu 2 OH 2 CO 3 ] are sometimes found.
In the production of copper metal, the concentrated sulfide ore is roasted to remove part of the sulfur as sulfur dioxide. The remaining mixture, which consists of Cu 2 S, FeS, FeO, and SiO 2 , is mixed with limestone, which serves as a flux a material that aids in the removal of impurities , and heated. Molten slag forms as the iron and silica are removed by Lewis acid-base reactions:.
In these reactions, the silicon dioxide behaves as a Lewis acid, which accepts a pair of electrons from the Lewis base the oxide ion. Reduction of the Cu 2 S that remains after smelting is accomplished by blowing air through the molten material.
The air converts part of the Cu 2 S into Cu 2 O. As soon as copper I oxide is formed, it is reduced by the remaining copper I sulfide to metallic copper:. This impure copper is cast into large plates, which are used as anodes in the electrolytic refining of the metal which is described in the chapter on electrochemistry. At one time, panning was an effective method of isolating both silver and gold nuggets.
Due to their low reactivity, these metals, and a few others, occur in deposits as nuggets. The discovery of platinum was due to Spanish explorers in Central America mistaking platinum nuggets for silver. When the metal is not in the form of nuggets, it often useful to employ a process called hydrometallurgy to separate silver from its ores.
Hydrology involves the separation of a metal from a mixture by first converting it into soluble ions and then extracting and reducing them to precipitate the pure metal.
Representative equations are:. The silver is precipitated from the cyanide solution by the addition of either zinc or iron II ions, which serves as the reducing agent:. One of the steps for refining silver involves converting silver into dicyanoargenate I ions:. Explain why oxygen must be present to carry out the reaction.
Why does the reaction not occur as:. The charges, as well as the atoms, must balance in reactions. Whenever something loses electrons, something must also gain electrons be reduced to balance the equation.
During the refining of iron, carbon must be present in the blast furnace. Why is carbon necessary to convert iron oxide into iron? The carbon is converted into CO, which is the reducing agent that accepts electrons so that iron III can be reduced to iron 0. The bonding in the simple compounds of the transition elements ranges from ionic to covalent.
In their lower oxidation states, the transition elements form ionic compounds; in their higher oxidation states, they form covalent compounds or polyatomic ions. The variation in oxidation states exhibited by the transition elements gives these compounds a metal-based, oxidation-reduction chemistry.
The chemistry of several classes of compounds containing elements of the transition series follows. Anhydrous halides of each of the transition elements can be prepared by the direct reaction of the metal with halogens. For example:. Heating a metal halide with additional metal can be used to form a halide of the metal with a lower oxidation state:.
The stoichiometry of the metal halide that results from the reaction of the metal with a halogen is determined by the relative amounts of metal and halogen and by the strength of the halogen as an oxidizing agent.
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