Why do the electron configurations of chromium and copper seem to disagree with what is expected according to the Aufbau principle? Chemistry Electron Configuration Electron Configuration.
Jul 7, Related questions How do electron configurations in the same group compare? How do the electron configurations of transition metals differ from those of other elements? How do electron configurations affect properties and trends of a compound? What are the d-block elements known as? What block is cadmium in? Which block are the transition elements in? What block are the transition metals in? What chemical elements are in the D block of the periodic table? What is the configuration for chromium?
What are the d block elements known as? When was Life on D-Block created? When was No Security - D-Block album - created? When was Gene D. Block born? What are d block elements? People also asked. Why is iron placed on d block of the periodic table? View results. Study Guides.
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Tungsten is commonly used as the filament in electric light bulbs. Why is tungsten particularly suited to this purpose?
Palladium metal is used to purify H 2 by removing other gases. Why is Pd so permeable to H 2? The Hg—Hg bond is much stronger than the Cd—Cd bond, reversing the trend found among the other transition-metal groups.
Explain this anomaly. The atomic radii of vanadium, niobium, and tantalum are pm, pm, and pm, respectively. Why does the radius increase from vanadium to niobium but not from niobium to tantalum? The most stable oxidation state for the metals of groups 3, 4, and 5 is the highest oxidation state possible. In contrast, for nearly all the metals of groups 8, 9, and 10, intermediate oxidation states are most stable.
Most of the transition metals can form compounds in multiple oxidation states. Give the valence electron configuration of Ru in each oxidation state.
Why does Ru exhibit so many oxidation states? Which ones are the most stable? Which of the three metals do you expect to form the most stable dioxide? The chemistry of gold is somewhat anomalous for a metal. Does it form a stable sulfide? What would be its electron configuration? The compound CsAu has been isolated; it does not exhibit a metallic luster and does not conduct electricity.
Is this compound an alloy? What type of bonding is involved? Why not? What products are formed if a solution of aqueous sodium hydroxide is added to an aqueous solution of mercurous nitrate [Hg 2 NO 3 2 ]? Mercurous sulfide has never been prepared. What products are formed when H 2 S gas is bubbled through an aqueous solution of mercurous nitrate? Because ionization energies increase from left to right across the d block, by the time you reach group 9, it is impossible to form compounds in the oxidation state that corresponds to loss of all the valence electrons.
Very few of the transition metals are found in nature as free metals. Consequently, almost all metallic elements must be isolated from metal oxide or metal sulfide ores. Metallurgy A set of processes by which metals are extracted from their ores and converted to more useful forms. Metallurgy consists of three general steps: 1 mining the ore, 2 separating and concentrating the metal or the metal-containing compound, and 3 reducing the ore to the metal.
Additional processes are sometimes required to improve the mechanical properties of the metal or increase its purity. After an ore has been mined, the first step in processing is usually to crush it because the rate of chemical reactions increases dramatically with increased surface area. Next, one of three general strategies is used to separate and concentrate the compound s of interest: settling and flotation , which are based on differences in density between the desired compound and impurities; pyrometallurgy , which uses chemical reduction at high temperatures; and hydrometallurgy , which employs chemical or electrochemical reduction of an aqueous solution of the metal.
Other methods that take advantage of unusual physical or chemical properties of a particular compound may also be used. For example, crystals of magnetite Fe 3 O 4 are tiny but rather powerful magnets; in fact, magnetite also known as lodestone was used to make the first compasses in China during the first century BC. If a crushed ore that contains magnetite is passed through a powerful magnet, the Fe 3 O 4 particles are attracted to the poles of the magnet, allowing them to be easily separated from other minerals.
Metallurgy depends on the separation of a metal compound from its ore and reduction to the metal at high temperature pyrometallurgy or in aqueous solution hydrometallurgy. Settling and flotation have been used for thousands of years to separate particles of dense metals such as gold, using the technique known as panning , in which a sample of gravel or sand is swirled in water in a shallow metal pan. Because the density of gold Conversely, in flotation, the compound of interest is made to float on top of a solution.
The resulting froth is highly enriched in the desired metal sulfide s , which can be removed simply by skimming. This method works even for compounds as dense as PbS 7. In pyrometallurgy, an ore is heated with a reductant to obtain the metal.
Theoretically, it should be possible to obtain virtually any metal from its ore by using coke, an inexpensive form of crude carbon, as the reductant.
An example of such a reaction is as follows:. Unfortunately, many of the early transition metals, such as Ti, react with carbon to form stable binary carbides. Consequently, more expensive reductants, such as hydrogen, aluminum, magnesium, or calcium, must be used to obtain these metals. Many metals that occur naturally as sulfides can be obtained by heating the sulfide in air, as shown for lead in the following equation:.
The reaction is driven to completion by the formation of SO 2 , a stable gas. Pyrometallurgy is also used in the iron and steel industries. The overall reaction for the production of iron in a blast furnace is as follows:. As the ore, lime, and coke drop into the furnace Figure Molten iron is then allowed to run out the bottom of the furnace, leaving the slag behind.
Originally, the iron was collected in pools called pigs , which is the origin of the name pig iron. As the CO that is formed initially rises, it reduces Fe 2 O 3 to form CO 2 and elemental iron, which absorbs heat and melts as it falls into the hottest part of the furnace. It contains other impurities such as Si, S, P, and Mn from contaminants in the iron ore that were also reduced during processing that must be removed because they make iron brittle and unsuitable for most structural applications.
In the Bessemer process, oxygen is blown through the molten pig iron to remove the impurities by selective oxidation because these impurities are more readily oxidized than iron Figure In the final stage of this process, small amounts of other metals are added at specific temperatures to produce steel with the desired combination of properties.
The slag and the molten steel are removed by tilting the entire furnace and pouring the liquids out through the taphole. The most selective methods for separating metals from their ores are based on the formation of metal complexes.
For example, gold is often found as tiny flakes of the metal, usually in association with quartz or pyrite deposits. Virtually pure gold can be obtained by adding powdered zinc to the solution:. You have been asked to outline an economical procedure for isolating WS 2 from the ore and then converting it to elemental tungsten in as few steps as possible.
What would you recommend? Given: composition of ore. Asked for: procedure to isolate metal sulfide. Determine which method would be most effective for separating the metal sulfide from the ore. Then determine the best method for reducing the metal to the pure element.
You need to separate and concentrate the WS 2 , convert it to a suitable form so it can be reduced to the metal if necessary , and then carry out the reduction.
Because the new ore is a binary metal sulfide, you could take advantage of the hydrophilic nature of most metal sulfides to separate WS 2 by froth flotation. Then, because most metal sulfides cannot be reduced directly to the metal using carbon, you will probably need to convert WS 2 to an oxide for subsequent reduction. One point to consider is whether the oxide can be reduced using carbon because many transition metals react with carbon to form stable carbides.
Here is one possible procedure for producing tungsten from this new ore:. Propose an economical procedure for converting a silicate mineral deposit containing BaCO 3 to the pure Ba metal. The conversion of metals from their ores to more useful forms is called metallurgy , which consists of three general steps: mining, separation and concentration, and reduction. Settling and flotation are separation methods based on differences in density, whereas pyrometallurgy is based on a chemical reduction at elevated temperatures, and hydrometallurgy uses chemical or electrochemical reduction of an aqueous solution.
In pyrometallurgy, a reductant must be used that does not form stable compounds with the metal of interest. In hydrometallurgy, metals are separated via the formation of metal complexes.
Coke is a plentiful and inexpensive reductant that is used to isolate metals from their ores. Hydrometallurgy is the preferred method for separating late transition metals from their ores. What types of ligands are most effective in this process? Coke cannot be used as a reductant for metals that form stable carbides, such as the early transition metals La, Hf, and W.
Tantalum and niobium are frequently found together in ores. These elements can be separated from other metals present by treatment with a solution of HF. Explain why this is an effective separation technique. A commercially important ore of chromium is chromite FeCr 2 O 4 , which is an analogue of magnetite Fe 3 O 4.
Based on what you know about the oxidation states of iron in magnetite, predict the oxidation states of the metal ions in chromite. Write a balanced chemical equation for each reaction. Why is carbon not used for the reduction? Manganese is an important additive in steel because of its reactivity with oxygen and sulfur, both of which contribute to brittleness.
Predict the products of reacting Mn with these species. The diagram of a blast furnace in Figure Write a balanced chemical equation for each step of the process described in the figure and give the overall equation for the conversion. Oxygen is blown through the final product to remove impurities. Why does this step not simply reverse the process and produce iron oxides? Metallic Zr is produced by the Kroll method, which uses Na as the reductant.
Write a balanced chemical equation for each reaction involved in this process. The product is frequently contaminated with Hf. Propose a feasible method for separating the two elements. The compound Cr 2 O 3 is important commercially; among other things, it is used as a pigment in paint and as a catalyst for the manufacture of butadiene.
Write a balanced chemical equation to show how you would produce this compound from. Carbon cannot be used as a reductant because vanadium forms stable carbides, such as VC and VC 2.
One of the most important properties of metallic elements is their ability to act as Lewis acids that form complexes with a variety of Lewis bases. A metal complex A chemical compound composed of a central metal atom or ion bonded to one or more ligands. Electrically charged metal complexes are sometimes called complex ions An ionic species formed between a central metal ion and one or more surrounding ligands because of a Lewis acid—base interaction.
A coordination compound A chemical compound with one or more metal complexes. Coordination compounds are important for at least three reasons. First, most of the elements in the periodic table are metals, and almost all metals form complexes, so metal complexes are a feature of the chemistry of more than half the elements.
Second, many industrial catalysts are metal complexes, and such catalysts are steadily becoming more important as a way to control reactivity. Finally, transition-metal complexes are essential in biochemistry. Examples include hemoglobin, an iron complex that transports oxygen in our blood; cytochromes, iron complexes that transfer electrons in our cells; and complexes of Fe, Zn, Cu, and Mo that are crucial components of certain enzymes, the catalysts for all biological reactions.
Metal complexes are so important in biology that we consider the topic separately in Section Coordination compounds have been known and used since antiquity; probably the oldest is the deep blue pigment called Prussian blue: KFe 2 CN 6.
The chemical nature of these substances, however, was unclear for a number of reasons. And why should a KF:AlF 3 mixture have different chemical and physical properties than either of its components? Like the double salts, the compositions of these adducts exhibited fixed and apparently arbitrary ratios of the components. The Great Wave Off Kanagawa. The Japanese artist Katsushika Hokusai used Prussian blue to create this famous woodcut.
Although the chemical composition of such compounds was readily established by existing analytical methods, their chemical nature was puzzling and highly controversial.
The major problem was that what we now call valence i. The modern theory of coordination chemistry is based largely on the work of Alfred Werner —; Nobel Prize in Chemistry in In a series of careful experiments carried out in the late s and early s, he examined the properties of several series of metal halide complexes with ammonia. Werner, the son of a factory worker, was born in Alsace. He developed an interest in chemistry at an early age, and he did his first independent research experiments at age While doing his military service in southern Germany, he attended a series of chemistry lectures, and he subsequently received his PhD at the University of Zurich in Switzerland, where he was appointed professor of chemistry at age He won the Nobel Prize in Chemistry in for his work on coordination compounds, which he performed as a graduate student and first presented at age Apparently, Werner was so obsessed with solving the riddle of the structure of coordination compounds that his brain continued to work on the problem even while he was asleep.
In , when he was only 25, he woke up in the middle of the night and, in only a few hours, had laid the foundation for modern coordination chemistry. These data led Werner to postulate that metal ions have two different kinds of valence: 1 a primary valence oxidation state that corresponds to the positive charge on the metal ion and 2 a secondary valence coordination number that is the total number of ligands bound to the metal ion.
Unexpectedly, however, two different [Co NH 3 4 Cl 2 ]Cl compounds were known: one was red, and the other was green part a in Figure Because both compounds had the same chemical composition and the same number of groups of the same kind attached to the same metal, there had to be something different about the arrangement of the ligands around the metal ion.
His conclusion was corroborated by the existence of only two different forms of the next compound in the series: Co NH 3 3 Cl 3. What does the fact that no more than two forms of any MA 4 B 2 complex were known tell you about the three-dimensional structures of these complexes? Given: three possible structures and the number of different forms known for MA 4 B 2 complexes.
Asked for: number of different arrangements of ligands for MA 4 B 2 complex for each structure. Sketch each structure, place a B ligand at one vertex, and see how many different positions are available for the second B ligand. The three regular six-coordinate structures are shown here, with each coordination position numbered so that we can keep track of the different arrangements of ligands.
For each structure, all vertices are equivalent. We begin with a symmetrical MA 6 complex and simply replace two of the A ligands in each structure to give an MA 4 B 2 complex:.
For the hexagon, we place the first B ligand at position 1. There are now three possible places for the second B ligand: at position 2 or 6 , position 3 or 5 , or position 4. These are the only possible arrangements. The 1, 2 and 1, 6 arrangements are chemically identical because the two B ligands are adjacent to each other. The 1, 3 and 1, 5 arrangements are also identical because in both cases the two B ligands are separated by an A ligand.
Turning to the trigonal prism, we place the first B ligand at position 1. Again, there are three possible choices for the second B ligand: at position 2 or 3 on the same triangular face, position 4 on the other triangular face but adjacent to 1 , or position 5 or 6 on the other triangular face but not adjacent to 1.
The 1, 2 and 1, 3 arrangements are chemically identical, as are the 1, 5 and 1, 6 arrangements. In the octahedron, however, if we place the first B ligand at position 1, then we have only two choices for the second B ligand: at position 2 or 3 or 4 or 5 or position 6.
In the latter, the two B ligands are at opposite vertices of the octahedron, with the metal lying directly between them. Although there are four possible arrangements for the former, they are chemically identical because in all cases the two B ligands are adjacent to each other. The number of possible MA 4 B 2 arrangements for the three geometries is thus: hexagon, 3; trigonal prism, 3; and octahedron, 2.
The fact that only two different forms were known for all MA 4 B 2 complexes that had been prepared suggested that the correct structure was the octahedron but did not prove it. For some reason one of the three arrangements possible for the other two structures could have been less stable or harder to prepare and had simply not yet been synthesized. When combined with analogous results for other types of complexes e.
Determine the maximum number of structures that are possible for a four-coordinate MA 2 B 2 complex with either a square planar or a tetrahedral symmetrical structure.
Answer: square planar, 2; tetrahedral, 1. The coordination numbers of metal ions in metal complexes can range from 2 to at least 9. In general, the differences in energy between different arrangements of ligands are greatest for complexes with low coordination numbers and decrease as the coordination number increases. The following presents the most commonly encountered structures for coordination numbers 2—9.
Many of these structures should be familiar to you from our discussion of the valence-shell electron-pair repulsion VSEPR model in Chapter 9 "Molecular Geometry and Covalent Bonding Models" because they correspond to the lowest-energy arrangements of n electron pairs around a central atom.
Compounds with low coordination numbers exhibit the greatest differences in energy between different arrangements of ligands. Three-coordinate complexes almost always have the trigonal planar structure expected from the VSEPR model.
Two common structures are observed for four-coordinate metal complexes: tetrahedral and square planar. It is also found for four-coordinate complexes of the first-row transition metals, especially those with halide ligands e. This coordination number is less common than 4 and 6, but it is still found frequently in two different structures: trigonal bipyramidal and square pyramidal. Because the energies of these structures are usually rather similar for most ligands, many five-coordinate complexes have distorted structures that lie somewhere between the two extremes.
This coordination number is by far the most common. The six ligands are almost always at the vertices of an octahedron or a distorted octahedron. The only other six-coordinate structure is the trigonal prism, which is very uncommon in simple metal complexes. This relatively uncommon coordination number is generally encountered for only large metals such as the second- and third-row transition metals, lanthanides, and actinides.
By far the most common, however, is the pentagonal bipyramid. This coordination number is relatively common for larger metal ions. The simplest structure is the cube, which is rare because it does not minimize interligand repulsive interactions. Common structures are the square antiprism and the dodecahedron, both of which can be generated from the cube.
The thermodynamic stability of a metal complex depends greatly on the properties of the ligand and the metal ion and on the type of bonding. Recall that the metal—ligand interaction is an example of a Lewis acid—base interaction.
Lewis bases can be divided into two categories: hard bases A type of Lewis base with small, relatively nonpolarizable donor atoms. Metal ions with the highest affinities for hard bases are hard acids An acid with the highest affinity for hard bases.
It is relatively nonpolarizable and has a relatively high charge-to-radius ratio. It tends to be a cation of a less electropositive metal. Some examples of hard and soft acids and bases are given in Table Notice that hard acids are usually cations of electropositive metals; consequently, they are relatively nonpolarizable and have higher charge-to-radius ratios.
Conversely, soft acids tend to be cations of less electropositive metals; consequently, they have lower charge-to-radius ratios and are more polarizable. Chemists can predict the relative stabilities of complexes formed by the d -block metals with a remarkable degree of accuracy by using a simple rule: hard acids prefer to bind to hard bases, and soft acids prefer to bind to soft bases. Because the interaction between hard acids and hard bases is primarily electrostatic in nature, the stability of complexes involving hard acids and hard bases increases as the positive charge on the metal ion increases and as its radius decreases.
In general, the stability of complexes of divalent first-row transition metals with a given ligand varies inversely with the radius of the metal ion, as shown in the following series: The inversion in the order at copper is due to the anomalous structure of copper II complexes, which will be discussed shortly.
Because a hard metal interacts with a base in much the same way as a proton, by binding to a lone pair of electrons on the base, the stability of complexes of hard acids with hard bases increases as the ligand becomes more basic. For example, because ammonia is a stronger base than water, metal ions bind preferentially to ammonia.
Consequently, adding ammonia to aqueous solutions of many of the first-row transition-metal cations results in the formation of the corresponding ammonia complexes.
Complexes of soft metals with soft bases are therefore much more stable than would be predicted based on electrostatic arguments. Hard acids prefer to bind to hard bases, and soft acids prefer to bind to soft bases.
Recall from Section This is consistent with the increase in the soft character of the metals across the first row of the transition metals from left to right. Recall also that most of the second- and third-row transition metals occur in nature as sulfide ores, consistent with their greater soft character.
Correspondingly, a polydentate ligand is a chelating agent , and complexes that contain polydentate ligands are called chelate complexes. Experimentally, it is observed that metal complexes of polydentate ligands are significantly more stable than the corresponding complexes of chemically similar monodentate ligands; this increase in stability is called the chelate effect. Chelate complexes are more stable than the analogous complexes with monodentate ligands.
Re: Why are Copper and Chromium exceptions? Post by Eduardogonzalez1G » Mon Oct 12, am When doing the electron configurations for these elements, they are exceptions to the general rule because a completely full or half full d sub-level is more stable than a partially filled d sub-level, so an electron from the 4s orbital is excited and rises to a 3d orbital.
Post by Megna Patel 1I » Mon Oct 12, am These two elements are exceptions because it is easier for them to remove a 4s electron and bring it to the 3d subshell, which will give them a half filled or completely filled subshell, creating more stability.
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