Questions tagged [periodic-trends]
Trends which are observed in the properties of elements as you move along the periodic table in a given direction.
328
questions
-2
votes
0
answers
16
views
Transition metals [closed]
Similar to the halogen that decrease in reactivity down the group, what is the trend of reactivity for transition metals? What makes a transition metal more reactivity, and why does this occur in ...
-1
votes
0
answers
30
views
Is effective nuclear charge averaged over valence electrons?
In my textbook they speak of effective nuclear charge felt by valence electrons.
As I understand it the effective nuclear charge is not the same for all valence electrons.
In boron for example the 2s² ...
0
votes
0
answers
30
views
Extent of Melting of Bonds or Intermolecular Forces
I'm currently having a revisit on the subject of periodicity of the periodic table, and I came across an issue that is kind of bugging me.
If we take a look at the melting and boiling point trends of ...
-5
votes
1
answer
68
views
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 ...
- 7
-3
votes
1
answer
51
views
Doubt regarding trends in modern periodic table [closed]
We know that atomic radius decreases along a period and increases along a group. (Same goes for metallic character)
But if we take 2 elements A & B(A is at somewhere in the top and left in ...
-3
votes
1
answer
135
views
Why are certain gases with higher molar masses less dense than the ones that have a lower one?
Neon, despite having a larger molar mass than nitrogen, oxygen and fluorine, is less dense than all of them. This also goes that fluorine (again) and chlorine are both denser than argon, even though ...
- 795
0
votes
1
answer
55
views
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 ...
- 3
2
votes
3
answers
830
views
Why an atom is more stable when only sublevels s and p are full?
Supposedly when explaining electronegativity and stability of an element, they tell you that it is more stable if the last level is full. That works up to the third period, but after transition ...
1
vote
1
answer
144
views
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
6
votes
1
answer
259
views
Is there a canonical variable for period and group?
For example, "Z" is the standard symbol for atomic number. I'm writing a manuscript that uses the group and period of elements within some equations, and so far I'm just denoting them as $G_{...
1
vote
2
answers
113
views
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 ...
- 51
1
vote
1
answer
131
views
Does fluorine have 5 or 7 active valence electrons?
In a paper on chemical periodicities of elements, Cao et al. show the number of valence electrons in a periodic table (https://doi.org/10.1515/pac-2019-0901). Apart from Boron and Aluminum shown as ...
- 30k
1
vote
1
answer
133
views
How to know the group number from the ionization energy?
The successive ionization energy of the first four electrons of a representative element are $\pu{738.1 kJ/mol}$, $\pu{1450 kJ/mol}$, $\pu{7730 kJ/mol}$ and $\pu{10500 kJ/mol}$. Characterize the ...
- 233
0
votes
3
answers
58
views
Do Ions with less stability have less energy of ionization than those who are stable?
Problem. I've come up with the strange example of the third energy of ionization of both $\pu{Mg}$ and $\pu{Al}$, the standard logic that is to be applied on any problem of "which element has ...
- 135
2
votes
3
answers
2k
views
Which atom is the smallest atom?
Is hydrogen or helium the smallest atom? My teacher said that the smallest atom is the helium atom, but I think that the smallest atom is the hydrogen atom. It has a single electron and a single ...
0
votes
1
answer
178
views
Why is copper a better conductor of electricity than calcium?
How would we compare the electrical conductivity between copper and calcium? I understand that electrical conductivity of a metal is dependent on the number of delocalized electrons for that metal. ...
- 132
3
votes
1
answer
460
views
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 ...
- 287
5
votes
0
answers
155
views
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 ...
- 287
5
votes
1
answer
2k
views
Why does magnesium have a greater ionization energy than lithium?
I'm a high school student and I'm learning about ionization energy and atomic radius of elements. I want to compare the ionization energy of lithium and magnesium.
Here is the information provided in ...
- 281
0
votes
0
answers
210
views
Is Copernicium a transition metal?
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. ...
- 489
8
votes
2
answers
3k
views
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
votes
1
answer
241
views
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
0
votes
0
answers
66
views
Relation between Ionization energy and reactivity
So I was learning about the periodic table where I came across the topic of ionization energy. As a general trend the Ionization energy decreases as we move down a group with a few exceptions such as ...
2
votes
0
answers
62
views
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 $\Delta = (X-Y)_{measured}-(X-Y)_{theoretical}$ ...
- 321
4
votes
1
answer
1k
views
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 ...
- 365
4
votes
1
answer
175
views
Do organopolonium compounds exist?
Analogues of alcohols exist for all the heavier Group 16 elements, namely sulfur, selenium, and tellurium. Would polonium also be able to form a "polonol" like $\ce{CH3PoH}$?
- 795
3
votes
1
answer
300
views
Why is strontium(II) ion bigger than krypton atom?
$\ce{Sr^2+}$ is exactly the same as $\ce{Kr}$, in terms of electrons and orbitals.
The only difference between the two, is that $\ce{Sr^2+}$ has a couple of extra protons in the nucleus (and probably ...
- 39
1
vote
1
answer
91
views
Acidic character and anion stability across periods and groups of the periodic table [duplicate]
I understand that to compare relative acidity one must consider the stability of the conjugate bases.
Across a period the electronegativity of an element increases. And that is for example why $\ce{HF}...
- 11
0
votes
0
answers
96
views
Electron Affinity of Lead as compared to Bismuth
For "nitrogen family" and "carbon family" the trend goes that in a period, the electron affinity in case of group 15 is less than that of group 14. This is attributed to the half-...
- 131
0
votes
0
answers
42
views
S(p)-C(p) vs. O(p)-C(p) overlap
In Grossman, The Art of Writing Reasonable Organic Reaction Mechanisms, he provides the following explanation. The question asks to explain why the difference in pKa values between PhSH and EtSH is ...
- 49
4
votes
0
answers
40
views
Is there an enolate equivalent for enamines?
I'm learning that enolates are stronger than enamines are stronger than enols in terms of general nucleophilicity. Makes sense. But what I can't find any explanation for online is why the trend ...
- 49
1
vote
0
answers
105
views
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} &...
- 206
0
votes
0
answers
127
views
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 ...
- 193
2
votes
0
answers
59
views
Out of KCl, CaCl2, MgCl2, NaCl, which causes the greatest corrosion rate of iron and why?
I know that salts act as an electrolyte in a redox process and rusting of iron, where iron loses electrons and oxidizes, and oxygen gains electrons and reduces. I did an experiment with KCl, NaCl, ...
- 21
-2
votes
1
answer
52
views
Predict the valence configuration of this element using the first five ionization energies [closed]
If the first five ionization energies of an element are, respectively: $\pu{1.09 kJ/mol}$, $\pu{2.35 kJ/mol}$, $\pu{4.62 kJ/mol}$, $\pu{6.22 kJ/mol}$ and $\pu{37.83 kJ/mol}$, to which group of the ...
- 9
2
votes
1
answer
421
views
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 ...
0
votes
1
answer
80
views
The quantum mechanics behind periodicity of elements
Especially in high school/first-year undergraduate chemistry courses, we learn with great dedication the periodicities along groups and periods. There are various useful and interesting trends.
I ...
- 189
0
votes
1
answer
447
views
Why is boiling point of Ammonia greater than Arsine?
I have previously read that the boiling point of Stibane(SbH3) is greater than Ammonia(NH3) as ammonia is gas at room temperature and no hydrogen bonding exists in the gaseous form of NH3.
Hence, as ...
15
votes
1
answer
1k
views
Why doesn't ionization energy decrease from O to F or F to Ne?
I know that in general, the first ionization energy increases across a period due to increasing nuclear charge, reasonably constant shielding & decreasing atomic radius.
From N to O, however, the ...
- 534
0
votes
1
answer
266
views
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 ...
- 377
0
votes
1
answer
52
views
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|$$
Flipped inequality if acid.
I ...
- 229
-1
votes
1
answer
194
views
Question on d block contraction
For size trend down a group, it is known that:$$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 ...
- 229
6
votes
1
answer
96
views
Why can’t lanthanum through lutetium and actinium through lawrencium all be in group 3?
In 2015, IUPAC established a task force to “deliver a recommendation in favor of the composition of group 3 of the periodic table.” Not much about their decision-making process has been made known to ...
2
votes
1
answer
45
views
Find the Ionisation Potential and Electron affinity of X
$N_0/2$ atoms of $X_{(g)}$ are converted into $\ce{X^+_{(g)}}$ by energy $E_1$. $N_0/2$ atoms of $X_{(g)}$ are converted into $\ce{X^-_{(g)}}$ by energy $E_2$.
Hence ionisation potential and electron ...
-2
votes
1
answer
60
views
Reactivity Dilemma of elements [closed]
While learning Periodic Properties, I stumbled upon a doubt regarding reactivity of elements of period 2 and period 3.
(I am denoting reactivity, of any $X$ element as $R_{X}$.)
For reactivity of $s-...
- 159
5
votes
1
answer
1k
views
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 ...
- 97
5
votes
1
answer
600
views
Covalent atomic radii: oxygen vs nitrogen
Many books state that $R_\ce{N} > R_\ce{O}$ which is in accordance with the general trend. However, some books say that $R_\ce{O} > R_\ce{N}$ because of repulsion caused by pairing of electrons.
...
- 264
3
votes
1
answer
177
views
Is there an opposite to shielding effect? [closed]
I recently read about shielding effect and lowering of effective nuclear charge due to penetration of other electrons. I wonder while doing calculations involving Slater's rules the electrons from ...
3
votes
0
answers
398
views
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,...
- 31
1
vote
1
answer
1k
views
Trend in atomic volume across a period [closed]
"Atomic volume decreases along a period, reaches a minimum at the middle, and then increases for the rest of the period"
Why does the atomic volume, along a period, initially decrease, ...
- 411