Questions tagged [periodic-trends]
Trends which are observed in the properties of elements as you move along the periodic table in a given direction.
357
questions
1
vote
0
answers
16
views
Why is there anomalous trend in third ionization energy for Pr-Pm and Dy-Er?
It is not hard to observe the anomalously flat regions at Pr-Pm and Dy-Er in the trend of IE3 of lanthanides:, each described as the "first quarter" and "third quarter". Why is ...
0
votes
0
answers
39
views
Can the relative reactivity of metals be explained by ionization energy and/or electronegativity?
I'm a 9th grade physical science teacher, and we're currently learning periodic trends. This is the first chemistry my students have learned. One of our labs for this unit has to do with the relative ...
1
vote
1
answer
64
views
How would you explain the general trend in melting point between Group 1 and Group 2 chlorides?
This question is based off of the attached chart. I notice how there's a general increase in melting point down group 2 chlorides and a general decrease (except for Lithium) down the group 1 chlorides....
0
votes
1
answer
165
views
Ionic radii of cations and anions
My textbook mentions that across a period from left to right, the ionic radius of atoms decreases. I'm a bit puzzled because negative ions in the same period have an extra shell. I get the part about ...
0
votes
1
answer
46
views
Does Cu+ have a greater ionic radius than Sr2+?
Although Strontium is in group 2, reducing the number of electrons as it becomes ionized makes it group 18, period 4 in terms of electrons. Therefore, ionized Strontium (Sr2+) is in the same period as ...
-2
votes
2
answers
206
views
Why aren't lanthanum, praseodymium, osmium, and mercury not on the same energy level?
The following question is from "The Official Guide to the HiSET Exam, Second Edition 2nd Edition", published by McGraw Hill, 2nd edition (March 25, 2016).2016 text, p. 75 (ISBN10: 1259640795)...
-4
votes
1
answer
178
views
Queries regarding Lanthanoid Contraction
Consider these two statements regarding lanthanoid contraction and their explanation as understood by me.
Lanthanoid contraction is the greater than expected decrease in the atomic radii of the ...
-3
votes
3
answers
369
views
Are periods the horizontal numbers on the periodic table and groups the vertical numbers?
I am writing this post so that I can ensure for my upcoming SUC3U0 (Chemistry, Grade 11) course test of nomenclature is correct. It's a Review of my Grade 10 General Science Course.
My teacher stated ...
0
votes
0
answers
38
views
Do the paired electrons of subshells' degenerate orbitals contribute to the total exchange energy?
For instance, in d7, there are 5 electrons with the same spin, and 2 electron with the opposite spin, meaning that there are only 3 unpaired electrons. So, which of these would be correct?
(i) Total ...
0
votes
0
answers
21
views
Some advice on inorganic textbook [duplicate]
I'd like to have some advice on Inorganic textbooks.
I've already consulted some books (Kettle, Drago, Keiter, Cotton) and they are all very useful, but now I'm searching for a textbook which focuses ...
0
votes
1
answer
358
views
Why does Cr have higher melting point in the 4 period among the transition metal? [duplicate]
There is a lot of answer stating that the low enthalpy of atomisation in Cr is due to the reason of partially filled d orbital, thus having extra stability. This makes the orbital more attracted ...
-2
votes
3
answers
158
views
Why is there a non-uniformity in even the reasons that explain exceptions in the trends in chemistry? [closed]
I have been studying the periodic table and several properties of atoms like the Ionization Energy, Atomic Radii, Electron gain enthalpy, Electronegativity etc.
Now, each property has somewhat of a &...
0
votes
0
answers
400
views
Please explain the order of Lewis acidic strength in trichlorides of boron group
The order of decreasing Lewis acid character as per online sources is as follows:
BCl3 > AlCl3 > GaCl3 > InCl3
Reason cited is: As we move down the group, the size of atom increases, and as a ...
3
votes
4
answers
431
views
Comparison of atomic radii of boron and beryllium
Let me write down a couple of facts and this will be easier for you to know the essence of the question.
Radius of boron is smaller than beryllium.
Ionization energy of boron is smaller than ...
-2
votes
1
answer
65
views
Order of Second Ionisation Potential of C, N, O and F
Here's what I believe:
The electronic configurations of the elements after losing 1 electron are:
N+ -> 1s2 2s2 2p2
O+ -> 1s2 2s2 2p3
F+ -> 1s2 2s2 2p4
So, on losing 1 e- more, the value of ...
1
vote
0
answers
21
views
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+ ...
1
vote
0
answers
29
views
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 ...
0
votes
1
answer
442
views
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-...
0
votes
2
answers
179
views
Why ionic radius increases with negative charge?
Here's my understanding:
An ion with a negative charge has gained electrons. Hence the negative charge.
With a greater negative charge, there should be more attraction towards the positive charge.
As ...
2
votes
2
answers
270
views
How did Mendeleev improve on the Newland's table?
I understand that John Newland’s law of octaves was ridiculed by the scientific community as his table failed to work past calcium. I'm trying to understand how Mendeleev’s table improved on this.
On ...
0
votes
2
answers
116
views
Is the periodic table ordered by bonded atoms and does that change the electron configurations and ordering? [closed]
In my book (Mortimer, The Basic Knowledge of Chemistry) the electron structure of the elements is introduced, there the relative energies of the atomic orbitals are shown:
1s < 2s < 2p < 3s &...
4
votes
1
answer
488
views
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.
...
0
votes
0
answers
69
views
Why middle elements of transition series show more number of oxidation states [duplicate]
Why do the elements in the middle of the transition series show more number of common oxidation states than others?
2
votes
2
answers
329
views
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 ...
1
vote
2
answers
2k
views
Reason for exceptions in I.E. trend in group 13
In general, we would expect IE to decrease down a group. This is because atomic radius increases $\implies$ valence electrons are further from nucleus $\implies$ less effective nuclear attraction on ...
0
votes
1
answer
129
views
Trends in atomic radii across a period
I am a 12th grader. Recently, while revising the Periodic Table, I came across the statement:
As the effective nuclear charge increases across a period, the atomic radius of the elements decreases on ...
0
votes
2
answers
704
views
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 ...
0
votes
2
answers
6k
views
Why is effective nuclear charge said to be decreased down the group, but the Zeff calculated is increased down the groups instead?
Some textbook write that effective nuclear charge is constant when gping down the group,while some write that the effective nuclear charge decrease down the group
So which statement is true? I try to ...
-3
votes
1
answer
153
views
Confusion regarding 1st and 2nd electron gain enthalpy
$\ce{O}$ has the 1st electron gain enthalpy $\pu{-141 kJ mol-1}$. $-ve$ value implies that energy is released when electron is added to an isolated atom. This also means that if $\pu{141 kJ}$ energy ...
1
vote
1
answer
97
views
Reason of being 2nd ionization energy
Why is the second ionization energy always greater than the first? By shielding effect, it shouldn't have been true. Let's take $\ce{Mg}$ and $\ce{Mg^+}$ for example. Effective nuclear charge(ENC) for ...
0
votes
0
answers
63
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
86
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 ...
-4
votes
1
answer
78
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
724
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 ...
1
vote
1
answer
385
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 ...
2
votes
3
answers
1k
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
1k
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. $r_\ce{Li+}<r_\ce{Na+}<r_\ce{K+}$...
6
votes
1
answer
272
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
227
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 ...
2
votes
1
answer
355
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 ...
1
vote
1
answer
1k
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 ...
0
votes
3
answers
238
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 ...
2
votes
3
answers
6k
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
653
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. ...
3
votes
1
answer
4k
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 ...
5
votes
0
answers
177
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 ...
5
votes
1
answer
3k
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 ...
0
votes
0
answers
357
views
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. ...
11
votes
2
answers
8k
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 ...
2
votes
1
answer
820
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 ...