Questions tagged [periodic-trends]
Trends which are observed in the properties of elements as you move along the periodic table in a given direction.
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Which of these models represent a binary lithium compound and with which element? [on hold]
A chemist performs reactions that produce binary lithium compounds. These elements include sulfur, chlorine, nitrogen, fluorine, selenium, oxygen, and iodine.
I think the elements are chlorine ...
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0answers
30 views
Nature of Monoxides of Carbon family
well CO is neutral, PbO and SnO is amphoteric but what about the nature of GeO?
In my textbook it's given that its basic in nature but in another its given that acidic in nature. and wikipedia says ...
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1answer
53 views
Density of D-block elements
Something that confuses me slightly is the trends in density when comparing periods 4, 5, and 6 in the d-block. Looking at periods 5 and 6, the density peaks at group 8, with Ruthenium and Osmium ...
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3answers
74 views
If Mg(OH)2 is insoluble, why does the reaction of MgO and water produce a slightly alkali solution? [closed]
The equation of the reaction is:
Mg(OH)2 + H2O -> Mg(OH)2.
Why is it that this reaction produces a solution of around pH 9? There are no OH- ions produced.
2
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0answers
69 views
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 ...
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1answer
102 views
Why it the electron affinity of beryllium is greater than nitrogen? [closed]
As we know that fully filled electronic configuration is more stable than half filled electronic configuration, so in my opinion beryllium's electron affinity should be less than nitrogen's.
Is my ...
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1answer
154 views
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 ...
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0answers
36 views
Comaparing melting points of group 14 elements [duplicate]
I found that melting point of $\ce{Sn(232°C)}$ is less than $\ce {Pb (327.5°C)} $ but i also saw that the bond enthalpy of $\ce {Sn-Sn(187.1 ±0.3 kJ mol^{-1})}$ is more than $\ce{Pb-Pb 86.6 ±0.8 kJ ...
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1answer
96 views
Octet rule violation in Period 2 elements [duplicate]
My textbook states,
Period 2 elements typically obey the octet rule. Period 3 and later elements can expand their valence shells. Elements in Periods 5 and 6 of the p-block show variable valence (...
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1answer
114 views
Why is the melting point of hydrogen fluoride lower than that of ammonia?
The melting point of hydrogen fluoride is -83.6°C, as compared to that of ammonia, which is -77.73°C. How does this make any sense?
Both hydrogen fluoride and ammonia show hydrogen bonding, which "...
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1answer
214 views
Is there any difference between negative electron gain enthalpy and electron affinity?
According to electron affinity,it is the amount of energy "released" during the addition of an electron in the valence shell of an isolated gaseous atom, and its sign convention is opposite to that of ...
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2answers
321 views
Why is the electronegativity of indium greater than that of thallium?
Why is the electronegativity of indium greater than that of thallium?
One possibility which I had assumed was the poor shielding effect by the d and f orbitals which leads to an increase in the ...
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0answers
96 views
Mismatch in the trends of atomic size and atomic radius
In the periodic table, the atomic radius decreases as we move from left to right in a period. However, the atomic volume should also decrease as a result of the decrease in atomic radius, as volume is ...
1
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1answer
93 views
What is the true depiction of the periodic table?
Normally with the periodic table the lanthanide series is separated out because it's long and would make the table wide. I looked for an expanded version and found this:
I found it kind of strange ...
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1answer
537 views
Rule to determine the total number of elements in a period [closed]
If each orbital can take maximum of 3 electrons, then total number of elements in 2nd and 4th periods respectively are = ?
I am not aware of the rule which helps to determine the total number of ...
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1answer
1k views
Why does oxygen have less negative electron gain enthalpy than sulphur? [duplicate]
Oxygen has less negative electron gain enthalpy than sulphur.
This statement is given in my book with a short reason:
due to compact size of oxygen
I'm unable to understand why. I would ...
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1answer
364 views
Why does hydride acidity increase across period and down group in periodic table?
Why exactly does hydride acidity increase across period and down group in periodic table? What is the explanation with respect to electrons? I can't figure this out because for 1st period etc H is an ...
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0answers
313 views
Why Gallium has less atomic radius than Aluminium but Thallium has more atomic radius than Indium? [duplicate]
All four elements mentioned here belong to the 13th group, where they follow the order- Al, Ga, In, Tl. Gallium's atomic size is less than that of Aluminium, because of the poor shielding effect of ...
2
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1answer
341 views
Why does the stability of hydrides decrease down the group in nitrogen family?
Why does the stability of hydrides decrease down the group in nitrogen family? Does this have to do with the fact that $\ce{NH3}$'s $\ce{N}$ is hybridised ($\ce{sp^3}$) while the rest of the group ...
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2answers
122 views
Comparing ionic character of group 1 elements
According to Fajan's rule ionic character should increase down the group as the size of cation increase.
So it must be
$$\ce{LiH < NaH < KH < RbH < CsH}$$
However, the following two ...
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1answer
753 views
Difference between basicity and reducing character
My understanding of basicity and reducing character:
Reducing character is the ability of a substance to reduce something else. So it itself must get oxidized. Since $\ce{BiH3}$ has a large radius, ...
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1answer
625 views
Trends in ionization energy in the second period [closed]
Question
Which element among the following has the highest ionisation energy: fluorine, oxygen, neon.
I know that all these elements belong to period 2 and ionisation energy increases from left ...
5
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1answer
1k views
Boiling point trend in group 13
My Theory:
Since atomic mass increases down the group, the van der Waal's forces should also operate to a greater extent, thereby making it difficult to change the phase of the substance. Hence, ...
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1answer
194 views
Why does cobalt have no negative charge?
I would like to know why cobalt cannot have a negative charge (or at least why a negative charge for cobalt isn't typical). I am not sure where I have gone wrong in my reasoning.
The electronic ...
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1answer
354 views
Why does hydration of ions depend on their charge to area ratio?
The following is written in my book Concise Inorganic Chemistry by J. D. Lee.
Hydration energy, hydrated radius and hydration number of a particular ion depends upon charge per unit area. Hence ...
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1answer
278 views
Trend in reducing property of dioxides
I am not sure of the explanation for the following statement:
The reducing property of dioxides of group 16 elements decreases from $\ce{SO2}$ to $\ce{TeO2}$.
Is the statement valid? If yes, how ...
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0answers
601 views
Abnormal ionisation energy trend: Group 13 and 14
I was going through some ionisation energy data, where I came across the following:
Ionisation energy order for Group 13 and 14:
B > Al ≈ Ga > In < Tl
C > Si > Ge > Sn < Pb
What could be the ...
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0answers
160 views
Ionic character of group 13 fluorides
Why do fluorides of group 13 elements have highly ionic character?
Does it have anything to do with the large electronegativity of fluorine?
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0answers
534 views
Exceptional electronic configuration?
The general electronic configuration for f-block is: (n-2)$f^{0-14}$ (n-1)$d^{0-2}$ n$s^2$.
Then why the configuration of Thorium is [Rn] $6d^2$ $7s^2$.
It should be [Rn] $5f^1$ $6d^1$ $7s^2$ as per ...
2
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1answer
1k views
Order of second ionization energy for cations
Why is the correct order of second ionisation potential of $\ce{Li , Be , B , C }$ such as: $\ce{Be} <\ce C <\ce B <\ce{Li} $?
I understand that $\ce{Li+}$ has a stable inert gas electronic ...
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1answer
281 views
Why doesn't D block contraction affect the other P block groups 14 15 16 etc
Usually we come across anomalies in the trends of periodic properties for example the size [Atomic radius value from Raymond Chang Chemistry 9th Edition] of Gallium (135 pm) is smaller than Aluminium (...
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0answers
78 views
Comparision of the Ionisation Energy Change of the alkali metals and noble gases?
Currently I compare the ionisation energys of the alkali metals:
Li: $\pu{0.52 eV}$
Na: $\pu{0.50 eV}$
K: $\pu{0.42 eV}$
Where only a slight drop (appr. remain constant) occurs.
This ionisation ...
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1answer
535 views
Electronegativity trends: Is it more important to prioritize families or periods? [closed]
I know that an atom that an atom is more electronegative as it moves up a group or right on a period (in terms of the periodic table).
So if you have two atom that is diagonally across from each ...
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0answers
333 views
Rationalising the trend of standard electrode potentials between the +II and +III oxidation state of first-row transition metals
Trends in standard electrode potentials of d block elements:
An examination ofthe $E^0 (\ce{M^3+}/\ce{M^2+})$ values (Table 8.2) shows the varying trends. The low value for Sc reflects the ...
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1answer
51 views
Quickly deduce block (s, p, d …) from atomic number [closed]
A question from previous year papers of IIT JEE. There's not enough time to write the electronic configuration in the exam. Please suggest a quick, objective approach.
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1answer
258 views
Why are group 1 elements so low in density?
I was studying the s-block elements and found that they extremely low in density. Lithium is said to be the least dense solid in the entire periodic table and their Cohesive Energies are also very low....
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2answers
2k views
Confusion between electronegativity and electron affinity
Electronegativity is a chemical property that says how well an atom can attract electrons towards itself.
The electron affinity of an atom or molecule is defined as the amount of energy released ...
3
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0answers
592 views
Non existence of B3+ in solution [closed]
I read that B3+ ions do not exist in aqueous solution, because hydration energy cannot compensate for the sum of first three ionisation energies.
This leads me to the following questions:
If boron (...
1
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2answers
1k views
Which element has larger atomic radius — beryllium or xenon?
I say that xenon radius is smaller comparing to beryllium, but my friend says otherwise.
What I think is that xenon is down in periodic table comparing to beryllium (3 periods down) and it's far ...
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1answer
80 views
Do the spins of outer orbitals block measurement of spin of inner orbitals?
Do the outermost s1 and s2 electrons block an outside observer from measuring the larger inner group orbitals for elements heavier than Nitrogen (for instance, would Chromium's 4s1 electron or ...
4
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1answer
5k views
Thermal stability of alkali metal hydrides and carbonates
Why is it that thermal stability of alkali metal hydrides decreases down the group, but for carbonates, it increases?
I used Fajan's rule to check for ionic character but somehow this is only ...
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1answer
2k views
Difference between Oxidation Potential and Ionization Potential [closed]
Ionization potential indicates a substance's tendency to loose electron and become a positive ion. So, a substance becomes ion more easily if it has a lower ionization potential (lower energy needed ...
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1answer
548 views
Acidity/basicity of oxides across the periodic table [duplicate]
Recently while self-studying my chemistry book, it dawned on me that metals form basic oxides and nonmetals forma acidic oxides. Why is this?
2
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1answer
4k views
Regular decrease in the atomic radius of 3d series
While comparing atomic radius, two factors are important:
A. Decrease in size due to increase in effective nuclear charge
B. Increase in size due to increase in shielding effect
I was surprised to ...
3
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1answer
832 views
On the periodic table: Why are groups of elements organized by 'letter' [duplicate]
Why are the groups of elements on the periodic table organized into areas represented by the letters s,p,d,f,g, and h?
What does this mean?
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0answers
85 views
Relative orbital energies of Mn and Ni
In this MO diagram, why are the atomic Mn $3d$ orbitals higher in energy than the Ni $3d$ orbitals?
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0answers
29 views
Deviation in bond angles (from standard $109°28'$ ) in hydrides of group 15 [duplicate]
Here are the approximate bond angles for first three members of group15.
$\ce{NH3}$: $107°$
$\ce{PH3}$: $94°$
$\ce{AsH3}$: $92°$
As we move down the group the bond angles approach towards $90°$. ...
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0answers
388 views
Scandide contraction and it's effect on trends on atomic radii
Radii of gallium is less than aluminium
**Ga-Ar 3d10 4s2 4p1
Al - Ne 3s2 3p1**
Reason : Due to poor shielding effect of electrons of d subshell (Alright )
But then why does the same not apply ...
3
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0answers
67 views
What proof is there that the “Island of Stability” exists?
Often I see people talking about an "Island of Stability" existing for super-heavy elements on the periodic table, but I don't see any reason to thinks this exists? Surely the heavier you go the more ...
5
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0answers
59 views
Trends in Slater's constant
I am aware of the various Slater rules to calculate the effective nuclear charge, $Z_\mathrm{eff}$
However, how can I decide the order in which the orbitals 2s, 3s, 3d, 3p, 4d, and 4f stand when ...
