All Questions
Tagged with periodic-trends inorganic-chemistry
118 questions
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Does 4d contraction exist?
4d due to having a higher principle quantum number and being a d orbital should have less shielding effect than 3d and since 3d contraction exists due to the poor shielding of 3d electrons 4d ...
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1
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55
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Why is the electron gain enthalpy of Al negative?
Aluminum has ${1s^22s^22p^63s^23p^1}$ electronic configuration. I'm unable to see any benefit it could have from gaining an electron. Yet, Aluminum has a negative electron gain enthalpy/positive ...
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1
vote
1
answer
74
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Is SbF3 ionic or covalent?
My textbook says:
Trihalides (of group 15) except BiF3 are predominantly covalent in nature.
But I see a lot of sources say that SbF3 is ionic. I am confused as to whether SbF3 should be taken as ...
- 13
2
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2
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587
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Is there no diagonal relationship for carbon and phosphorus?
As per the rule and what we were taught in our school, 2nd-period elements show a diagonal relationship with similar properties.
For example, lithium shows similar properties with magnesium, and boron ...
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42
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Was an accepted answer wrong in using the word "maximum"?
Melting and boiling points of transition elements
It was asked:
The melting and boiling points of transition elements increase from
scandium (1530 ∘C ) to vanadium (1917 ∘C ). They increase because ...
user151937
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1
answer
235
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Actinoid and lanthanide chemistry [closed]
I am a bit confused on lanthanide and actinide chemistry. Lanthanides have lower ionization energies and higher atomic radii and redox potential magnitudes than actinides but I also have read articles ...
user146836
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1
answer
71
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Effective nuclear charge increases along period despite increasing number of electrons
I learned that when an increasing number of electrons are present in the orbitals, then nuclear force decreases as it needs to hold more electrons.
Given this, why does the effective nuclear charge ...
1
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0
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26
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Trend in formation enthalpy of metal fluorides
Please see below for the data I am referring to. I don't really understand why the trend in Cr ceases and reverses.
I think I understand what the logic for WFn is - while the cost of forming Mn+ ...
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0
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44
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Why do the successive ionisation energies of Ni and Pt diverge?
The data I am referring to is below on the graph. The explanation I have found is that the 5d orbital of Pt is more diffuse than the 3d orbital of Ni, so is less sensitive to the increases in Zeff as ...
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1
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739
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Why is CrO3 an oxidising agent, but WO3 is not?
So apparently CrO3 can be used as an oxidising agent, but WO3 can not. I saw this on an assignment question which I will include below:
I think the reason why W6+ is 6-coordinate and Cr6+ is 4-...
4
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1
answer
610
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Lower melting points of zinc, cadmium and mercury
I am aware of the fact that d-block elements like zinc, cadmium and mercury have lower melting points than other d-block elements. Also I am aware that these three metals have a fully filled d shell.
...
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2
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486
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Why does the rate of change of atomic radius in the second period change so drastically?
I was reading in my textbook Chemistry Part I, Textbook for Class XI
by NCERT, ed. January 2021 that:
The atomic size generally decreases a period across as illustrated in Fig. 3.4 (a) for the ...
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2
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1k
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Why ionization energy of Thallium is higher than that of Indium?
I just normally calculated the effective nuclear charge (Zeff) for thallium and Indium from Slater's law, and I found it same for both! That is 5.(If you want calculation for answering or correcting ...
-5
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1
answer
89
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Can halogens show -3 or -5 or -7 oxidation state. Why? [closed]
I mean can we think it like if the electrons get excited into the d orbitals and because there are now more than one unpaired electron, why does it only loose them and why don't they accept more than ...
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1
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462
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Why is reaction of Li less vigorous than that of Na although the former has a more negative SRP value?
My textbooks says:
It may be noted that although lithium has most negative E0 value (Table 10.1), its reaction with water is less vigorous than that of sodium which has the least negative E0 value ...
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2
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1
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Why are hydrated lithium ions' radii larger than hydrated sodium ions' radii?
Why are hydrated lithium ions' radii larger than hydrated sodium ions' radii i.e. $r_\ce{Li+(aq)}>r_\ce{Na+(aq)}$?
If ionic radii increase down the group i.e. $r_\ce{Li+}<r_\ce{Na+}<r_\ce{K+}$...
user119959
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2
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273
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The oxidation number of N and Cl in NOClO4
My doubt is not about the solution itself, actually I was able to find the solution myself.
We could split NOClO4 as (NO+) + (ClO4-) and then proceed, but here I "knew" this split. Is there ...
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1
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5k
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The melting and boiling point decreases down the group up to group 14 (not including transition metals), but the trend reverses from group 15. Why?
In groups 1, 2, 13 and 14, the melting and boiling point decreases down the group with a few exceptions. In group 15 the melting/boiling point increases up to Arsenic and then started decreasing. In ...
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187
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What determines the kind of Bravais lattice structure (body-centred cubic, hexagonal, etc) a transition metal shows?
With the exception of Zn, Hg, Cd and Mn transition metals most transition metals have only one kind of lattice structure at room temperature. Another trend I noticed was that Groups 3 and 4 have ...
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362
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Is Copernicium a transition metal? [duplicate]
Zinc, cadmium, mercury and copernicium belong to the group 12 of the periodic table. In my textbook , it is mentioned that zinc, cadmium and mercury are d-block elements, but not transition metals. ...
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2
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11k
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Exchange energy of d6 configuration
In NCERT Chemistry book, it is given as:
Exchange energy is responsible for the stabilization of energy state. Exchange energy is approximately proportional to the total number of possible pairs of ...
user112344
2
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1
answer
947
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Effect of d-orbital electron shielding on atomic radius
In a standard book it is given:
"Atomic radius of Gallium is less than that of Aluminium. This can be understood from the variation in the inner core of the electronic configuration. The ...
user112344
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0
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97
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Which oxidation states were used when Pauling developed his electronegativity scale?
Paulings electronegativity is a relative scale, based on the difference in electronegativity between X and Y, $\Delta EN = 0.102 \sqrt {\Delta}$, where $\Delta = (X-Y)_{measured}-(X-Y)_{theoretical}$ ...
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1
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4k
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Why do selenium , tellurium and polonium have more negative electron gain enthalpy than oxygen?
In my book(NCERT Chemistry Part I, Textbook for Class XI[1]) a list of values of electron gain enthalpies of various elements is given. According to that list, oxygen has less negative electron gain ...
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0
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310
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Why is the increase in covalent radius from As to Bi not as big as from N to P?
The following is the radius of Group $15$ elements:
$$\begin{array}{c|c} \hline
\text{Element} & \text{Covalent Radius }(\pu{pm}) \\ \hline
\ce{N} &75 \\
\ce{P} &110 \\
\ce{As} &...
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290
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Color of Flame Test for Alkali Metals
Lithium is known to have the highest ionization energy among Group 1 elements. Also, characteristic colours in the flame test arise due to the excitation and de-excitation of electrons. Then why ...
- 304
2
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1
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2k
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Why does the ionization enthalpy of elements across a period not follow a regular pattern while the atomic size always decreases?
First of all, I would like to mention that I am only talking about elements that aren't from the d or f blocks.
In order to further elaborate on my question, I would like to take the third period as ...
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1
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830
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Tendency of formation of complexes in Group-1 elements
My book states the following:
Down the group(Group-1), tendency to form complexes decreases due to decrease in charge density$\bigg(\frac{\text{charge}}{\text{radius}}\bigg).$ This results in ...
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61
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Why does this formula work?
My teacher gave us a formula for determining if a M-O-H like compound will act like a base or not.without explaining much.
Base if:$$|\chi_o-\chi_M|\gt|\chi_o-\chi_H|$$
Flipped inequality if acid.
I ...
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1
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422
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Question on d block contraction
For size trend down a group, it is known that:$$Al\gt Ga$$
Due, to d block contraction of gallium.
Why isn't this the case when it comes to silicon and germanium?
Won't the poor shielding effect from ...
- 257
5
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1
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3k
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Why is the electronegativity of potassium and rubidium same?
The electronegativity of potassium and rubidium is reckoned at 0.82 for both. Why is it same for both of them? Shouldn't it be less for rubidium as compared to potassium owing to the addition of one ...
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0
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1k
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why lawrencium is placed in f-block elements although its last electron enters in 6d-subshell?
The electronic configuration of lawrencium ($\ce{Lr}$) is $\mathrm{[Rn] 7s^2 5f^{14} 6d^1}$. As its last electron enters the $\mathrm{6d}$ sub shell, it should be a part of $\mathrm{d}$-block elements,...
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1
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6k
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What is the structure of CF3 radical? [duplicate]
In the class, I was told that $\ce{H3C^.}$ has a trigonal planar structure with the unpaired electron in $\mathrm{2p_z}$ orbital. But $\ce{H3C -}$ has a trigonal pyramidal structure.
But why does ...
- 185
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2
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Is the magnitude of ionisation enthalpy and ionisation energy is same?
In my textbook it is written that ionisation energy and ionisation enthalpy are two different quantities. ionisation energy is the amount of energy provided to extract an electron from the outermost ...
2
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1
answer
1k
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Scale to be considered for comparing electronegativities of nitrogen and chlorine
The Pauling scale gives the $\chi$ values of $\ce{N}$ and $\ce{Cl}$ to be $3.04$ and $3.16,$ respectively, but the Allen scale gives the $\chi$ values of $\ce{N}$ and $\ce{Cl}$ to be $3.066$ and $2....
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1
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758
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Why is phosphorus trifluoride the strongest Lewis acid among the phosphorus trihalides?
I had read that for the trihalides of boron, boron trifluoride is the weakest Lewis acid due to backbonding. The order I had seen was -
$\ce{BI3 > BBr3 > BCl3 > BF3}\$
$$\ce{}$
$- order of ...
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1
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925
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Comparing Electron affinity and electron gain enthalpy at 0 K
In my book it is given that first electron gain enthalpy is greater than second for elements. Should we compare the magnitudes in such cases or the actual numbers with signs? Does the same comparision ...
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5
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2
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4k
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Why Zn has highest ionisation enthalpy in 3d series?
Zn which has the highest ionisation enthalpy in 3d series.The reason given in my textbook is:
The value of zinc is higher because it represent ionisation from 4s level.
This is not correct because ...
- 470
8
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2
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3k
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Reorganization during ionisation for d block elements
This is a quote from my textbook:
The irregular trend in the first ionisation enthalpy of 3d lmetals,can be accounted for by considering that the removal of one electron alters the relative ...
- 470
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1
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130
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Shielding effects and atomic size [closed]
The atomic size on going from aluminum to gallium decreases because of poor shielding effect of the $(n-1)d$ electrons, but on going from copper to zinc, the size increases due to the same shielding ...
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3
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3k
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Why does hydrogen have a lower ionization energy than fluorine?
I found here that the ionization energy of hydrogen is $\pu{1312kJ/mol}$ and for fluorine, it is $\pu{1681kJ/mol}$. Now clearly, from the data, we can see that hydrogen has a lower ionization energy ...
user88339
8
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2
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6k
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Why is Aluminium oxide amphoteric?
I was reading my book, in which it mentioned that aluminium and gallium oxides are amphoteric and and indium and thalium oxide are basic in their properties.
But no explanation was given.
My main ...
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1
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2k
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Effective nuclear charge and Ionization energy
A common reason given on why 3rd ionization energy > 2nd > 1st is because of increasing effective nuclear charge.
As per my book $Z_\mathrm{eff}$ = Atomic number $-$ Number of inner electrons.
Now ...
- 23
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1
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258
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Why does the emission wavelength of sodium appear to be an exception despite the trend for ionisation enthalpies among alkali metals?
The wavelengths for emissions in the visible region for Group 1 elements is as follows:
$$
\begin{array}{lc}
\hline
\text{Element} & λ/\pu{nm} \\
\hline
\ce{Li} & 670.8 \\
\ce{Na} & 589.2 ...
- 111
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1
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Thermal stability order of NaF, MgF2 and AlF3
I came up with a question to arrange thermal stability order of $\ce{NaF}$, $\ce{MgF2}$ and $\ce{AlF3}$ and I think the answer is $\ce{NaF>MgF2>AlF3}$ because $\ce{Na+}$ has largest ionic radius ...
- 63
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1
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2k
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Lanthanoid Contraction
Why is the radius of Europium so unusually high and out of the general trend ? Moreover, at different sources I am getting different values of radii. In some (e.g., Wikipedia) the radii are following ...
4
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2
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2k
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How can an electron shield another electron of the same subshell?
While I was preparing for my upcoming exams, I stumbled upon this sentence which is bothering me quite a bit:
The contraction of the lanthanoids is due to the imperfect shielding of one electron by ...
- 53
3
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0
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337
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H-N-H bond angle in ammonia boron trifluoride adduct
In the reaction:
$\ce{NH3 + BF3 -> NH3-BF3}$ does the HNH bond angle increase or decrease?
Surely, the FBF bond angle decreases because boron changes from $\ce{sp^2 -> sp^3}$. But how can we ...
- 5,531
3
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1
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2k
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Second ionization energies of copper(Cu) and silver(Ag)
The ionization energies of copper and silver are
First ionization energy: Cu-745.5 kJ/mol Ag-731.0 kJ/mol
Second ionization energy: Cu-1958 kJ/mol Ag-2073 kJ/mol
Now, looking at the ionization ...
- 5,735
0
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1
answer
2k
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Is there any difference between negative electron gain enthalpy and electron affinity?
Electron affinity is the amount of energy "released" during the addition of an electron in the valence shell of an isolated gaseous atom. The sign convention is opposite to that of thermodynamics ...
- 1