Questions tagged [transition-metals]

For questions about the characteristic physical properties, chemical reactions, etc. of d-block elements, group 3-12, or their compounds. Do not use this tag if your questions is about general properties of metals, use [metal] instead. Also see [rare-earth-elements].

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527 views

Trends in the covalency of bonding across the transition metals

I am under the impression that the covalent character in the bonding of transition metal compounds increases across a group; in fact I think this is why they're called transition metals (a transition ...
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1answer
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Why can mercury(I) exist, but not zinc(I)?

Mercury shows variable valency while zinc does not. Its electronic configuration is $\ce{[Xe]\:4f^14 5d^10 6s^2}$. So it can donate the $\ce{6s^2}$ electrons and should only be able to form $\ce{Hg^2+}...
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Hydrodehalogenation of aryl chlorides

Palladium is the "go to" heterogeneous catalyst for dehalogenating aryl chlorides using hydrogen. What are the chemical (not economic) reasons for other precious metal catalysts not being as common or ...
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1answer
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Cr(II) and Mn(III) - their oxidizing and reducing properties?

My textbook states that $\ce{Cr^2+}$ is a reducing agent while $\ce{Mn^3+}$ is an oxidizing agent in spite of both having $\ce{d^4}$ configuration. The explanation states that when $\ce{Cr^2+}$ gets ...
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What is the chemistry behind black colour of platinum black? [duplicate]

Platinum is a silvery white metal and is highly unreactive then why it's powdered form "platinum black" is platinum metal but is black in colour. why would a metal such as platinum become black as a ...
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Why is Iron (Fe) difficult to reduce?

$\ce{Fe^3+ + e- -> Fe^2+} \quad +0.77$ $\ce{Fe^3+ + 3e- -> Fe} \quad -0.04$ $\ce{Fe^2+ + 2e- -> Fe} \quad -0.41$ $\ce{Zn^2+ + 2e- -> Zn} \quad -0.76$ $\ce{Co^2+ + 2e- -> Co} \quad -0.29$...
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2answers
926 views

Why does mercury in mercuric acetate have a lone pair?

The configuration of mercury ends with $6s^{2}$. In mercuric acetate, mercury is in the +2 oxidation state, so does it still have a lone pair?
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1answer
183 views

Hiyama vs Sonogashira coupling

Why is Sonogashira's coupling more feasible than Hiyama's coupling when both could occur? I have seen many examples in syntheses, here is one (the penultimate reaction):
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3answers
620 views

How can I understand the Lewis acid-base interaction of iron(III) and water?

The interaction between $\ce{H+}$ and $\ce{NH3}$ as respectively a Lewis acid and a Lewis base is clear for me. $\ce{NH3}$ has a lone electron pair and $\ce{H+}$ has no electrons, or, saying politely, ...
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Low melting point of Manganeese [duplicate]

Melting point of manganese is lower than that of other 3d series except copper and zinc. Melting point increases from scandium to chromium. The reason given in my book for this trend is the increase ...
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How do partially protonated sulfate ligands affect a metal's charge?

I'm currently reviewing the Periana-Catalytica system and I have a question about one of the intermediates, namely $\ce{[(bpym)Pt(OSO3H)2]^+}$, which is found in the following tutorial review. How do ...
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2answers
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Negative potential of the oxidation of iron(II) to iron(III)

The oxidation potential which I found on the internet the following reaction $$\ce{Fe^{2+} -> Fe^{3+} + e^-}$$ is $\pu{-0.77 V}$. But how can it be negative? Negative oxidation potential means ...
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1answer
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What is the electronic configuration of Cr (+1) ion

I believe it should be $\ce{d^5}$ , but i found out that it is $\ce{d^4s^1}$. Is it so? I have not found any explanation for the following. So why the strange configuration?
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809 views

Method to synthesize KAu(CN)2 (or KCN)?

Every reasonably effective method of electroplating $\ce{Au}$ onto another metal's surface (e.g. $\ce{Cu}$,$\ce{Ni}$,$\ce{Ag}$, etc.) involves use of $\ce{KAu(CN)2}$ or in some cases $\ce{KAu(CN)4}$ ...
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1answer
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Color of Anhydrous Transition Metal Salt

Why are some anhydrous transition metal salts colored? Here are some examples I found. Anhydrous cobalt(II) chloride ($\ce{CoCl2}$), with sky-blue color. Anhydrous chromium(III) chloride ($\ce{CrCl3}...
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Why do isomeric bis-ethylenediamine cobalt complexes react differently?

A compound $\ce{Co(en)2(NO2)2Cl}$ has been prepared in a number of isomeric forms.One form undergoes no reaction with $\ce{AgNO3}$ or $\ce{(en)}$ and is optically inactive. A second form reacts with $...
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1answer
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Why does copper react only with nitric acid? [duplicate]

When we are entering the chapter for acid and base, one of the reactions is about reacting metal with acid to form a salt and hydrogen gas. My teacher also informed us that a metal which is at a lower ...
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1answer
567 views

Questions related to distinguishing dimagnetism and paramagnetism and when is there magnetic properties

If a transition metal ion has both paired and unpaired electrons, would it be considered as showcasing paramagnetism or dimagnetism? I know that Fe2+, which has an abbreviated electronic configuration ...
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How to calculate denticity of ligands?

When looking at an ligand, how do I know its denticity? For instance, I know that though there are 2 lone pairs in $\ce{H2O}$, its denticity is only 1 due to geometrical reasons as the 2 of them can't ...
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What explains the very high density of osmium and iridium? [duplicate]

Iridium with a density of $22.56$ g cm-3 & osmium with $22.59$ g cm-3. Data from their respective Wikipedia pages. Only these two naturally occurring elements have such a high density. I wish to ...
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1answer
559 views

In crystal field theory, why do all the metal electrons enter the d orbitals and not the s orbital?

Suppose we have the complex $\ce{[Fe(H2O)6]}$. Iron has 26 electrons, and its electronic configuration is therefore $[\ce{Ar}]\,\mathrm{4s^2 3d^6}$, but in crystal-field theory, we say that the $\...
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1answer
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Differences between Fe3+ and Fe2+ [closed]

I would like to know the differences between Fe3+ and Fe2+ ions. I'm guessing they must differ in reactivity but I'm not sure how. Also, is there a way that we can observed the differences
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Why do we say metals are monoatomic in nature?

Are metals monoatomic or polyatomic in nature? For in crystalline form they also form molecular orbitals.
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Why aren't the copper(II) ions in CuSO4 precipitated by hydroxide ions from water?

From my own experience and literature, I know that $\ce{CuSO4}$ is well soluble in water and dissociates into $\ce{Cu^2+}$ and $\ce{SO4^2-}$. $\ce{Cu(OH)2}$, however, is not: $K_\mathrm{sp} = 2 \cdot ...
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Magnetic susceptibility trend

So I was recently looking at this website. http://www.fizika.si/magnetism/MagSusceptibilities.pdf It lists the susceptibility values for inorganic compounds, and I've noticed that the trends don't ...
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112 views

Why tungsten does not have stable configuration? [duplicate]

Whenever there are 4 unpaired electrons in d-orbital, elements try to attain stable electronic configuration. For example copper. Electronic configuration of copper should be [Ar]3d4 4s2, but it ...
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2answers
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How can titanium burn in nitrogen?

I was going through the properties of titanium when a certain thing caught my eye: It was the reaction of burning of titanium in nitrogen. I was astonished to read it as I knew that neither is ...
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2answers
543 views

Transition Metal Compounds

So I have a few dumb questions. I'm still in high school and am doing something on magnetic properties of transition metals. I'm facing a few roadblocks. 1) What're compounds like $\ce{CoBr2, CoCl2, ...
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Odd Acidity Trend in Hexaaqua Metal Complexes

In the following link (three quarters down the page) it states that theoretically there should be a proportional relationship between the ionic radius and pKa of a hexaaqua metal complex (provided ...
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1answer
29k views

Why is [PdCl4]2- square planar whereas [NiCl4]2- is tetrahedral?

The molecule $\ce{[PdCl4]^2-}$ is diamagnetic, which indicates a square planar geometry as all eight d electrons are paired in the lower-energy orbitals. However, $\ce{[NiCl4]^2-}$ is also $\mathrm{d^...
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1answer
180 views

General notation for one of the d-orbitals

What is the general notation to represent the d-orbital with $l=2$, $m_l=0$, i.e. the orbital normally referred to as $\mathrm{d}_{z^2}$. To elaborate more, this orbital can be ordered in various ways ...
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Is iron the most stable element in the periodic table?

According to the binding energy per nucleon vs mass number graph, it is observed that iron-56 has the maximum value of binding energy per nucleon ($\pu{8.75 MeV}$). It means that iron-56 is the most ...
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Reference request for properties of amorphous titanium carbide (a-TiC)

I assume through some side reaction I'm getting $\ce{TiC}$ in my $\ce{TiO2}$ samples after calcination and I need some basic information about the properties of amorphous $\ce{TiC}$. Is it ...
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324 views

Difference in color between the chromate and permanganate ions

As the title states, I'm wondering why the $\ce{[CrO4]^2-}$ and $\ce{[MnO4]-}$ ions display different colors in solution. Both of the metal ions have a $\mathrm{d}^0$ electron configuration, have the ...
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1answer
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How can the intense color of potassium permanganate be explained with molecular orbital theory?

In the permanganate ion, manganese is in the $+7$ oxidation state, therefore it is a $\ce{d^0}$ ion. $\ce{d^0}$ and $\ce{d^1^0}$ ions don't absorb visible spectrum radiation because there are no ...
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1answer
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What is the lattice structure of manganese?

A transition element is defined as the one which has incompletely filled d orbital in its ground state or in any one of its oxidation state. Zinc , cadmium and mercury are not typical transition ...
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4answers
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How many valence electrons do elements in the d block have?

I just noticed that on the periodic table it doesn't say how many valence electrons there are for each column in the d block. How do I find out how many valence electrons elements in the d block have?...
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1answer
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Making elemental sulfur from pyrite FeS2

Has anyone done this or know of a good experiment that would allow someone to make elemental sulfur from $\ce{FeS2}$ (iron pyrite)?
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1answer
485 views

Why does chlorine oxidise iron to iron(III), not iron(II)?

I was asked to predict the product of the reaction between iron metal and chlorine gas: $$\ce{Fe +Cl2->} ?$$ The product here is supposed to be $\ce{FeCl3}$. But how would we know if the product ...
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937 views

How can I dissolve copper but not zinc?

I have a zinc-body garden spray head with a brass garden hose thread stuck inside. This is actually an irritatingly common problem. Which got me wondering: What chemical means exist to dissolve ...
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1answer
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Transition metal and complexation

When can we say that such metal forms a complex? Are $\ce{Pd(OAc)2}$ and $\ce{Pd(PPh3)2Cl2}$ complexes?
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Why do transition metals form particularly stable complexes?

The pre-transition metal ions can form complexes but the ligands are weakly bound unless they are multidentate and thus benefit from the chelate effect. For example, crown ethers and cryptands. ...
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1answer
439 views

Orbital mixing in square planar D4h complexes

Consider a square planar $\ce{ML4}$ complex with $D_\mathrm{4h}$ symmetry. Which orbital should the $\mathrm{a_{1g}}$ SALC of the ligands mix with, $\mathrm{3d}_{z^2}$ or $\mathrm{4s}$? Both of those ...
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1answer
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Reaction of Cu in hydrochloric acid bath with exposure to air over several months?

I assume that copper will be slowly oxidized by oxygen, dissolved in water, forming copper(I) oxide (as stated here): $$\ce{4 \overset{\pm0}{Cu} + O2 -> 2 \overset{+I}{Cu}_2O}$$ Reaction rate ...
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2answers
456 views

Colorless nature of carbonyl complexes

Researching the coloration of transition metal complexes one day, I came across this reference on Wikipedia 1: I am not sure why this is so. Take $\ce{Mo(CO)_6}$, or any other carbonyl complex of the ...
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125 views

Iron (II) dioxygen reaction mechanism?

Ok so I'm confused about the mechanism for this process: Now the idea here is that iron first becomes oxidised to Fe(III) by placing an electron in the antibonding orbital of dioxygen. This is ...
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3answers
5k views

Why do iron(II) ions and chromium have different electronic configurations?

What I know: Empty 3d orbitals are higher in energy than empty 4s orbitals Aufbau Principle (electrons always go into an empty orbital with the lowest energy) Partially/half/fully filled 3d ...
4
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1answer
8k views

What is the reason for the anomalous electronic configuration of palladium? [duplicate]

The p block elements generally have the general valence shell configuration as $$n\mathrm{p}^{1-6}\,n\mathrm{s}^{1-2}.$$ Expected electronic configuration for palladium is $$\ce{^46Pd} = \mathrm{1s^2\,...
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3answers
18k views

Variation in atomic sizes in the transition elements

From left to right across a period, effective nuclear charge increases in the transition series, just like in the p block, and so atomic size decreases. Here the electrons are being added to the d ...
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2answers
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Exceptions to the Madelung rule for electronic configurations

The electronic configuration of platinum is $$\mathrm{[Xe] 4f^{14} 5d^9 6s^1}$$ and not $\mathrm{[Xe] 4f^{14} 5d^{10} 6s^0}$ or $\mathrm{[Xe] 4f^{14} 5d^8 6s^2}$. I see this question has already ...