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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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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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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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 ...
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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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How do the relativistic effects influence chemical bonding of hassium or other closely related super heavy elements?
While superheavy elements are notoriously unstable, there's plenty of theoretical research and even some experimental techniques are valid for nuclides decaying in a matter of seconds. They can verify ...
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Anomaly in boiling point as compared to melting point in d-block [duplicate]
Consider the following graph:-
In the above graph, it can be observed that the melting point of Chromium is higher than that of Vanadium (though there's not much greater difference despite the fact ...
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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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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 ...
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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 ...
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Why does chlorine have a higher electron affinity value than fluorine? [duplicate]
Why does chlorine have a higher electron affinity value than fluorine? Since this periodic property tends from the bottom up (in the group), the logic would be that the fluorine is the element with ...
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Atomic radius decreasing across a Periodic Table row - does the RPD of an orbital change depending of the element considered?
I have a concern regarding the RPD of an orbital. Does the RPD of an orbital depend on the $Z$ (i.e. on the element under consideration) ? Especially, can the RPD of an orbital "shrink" to ...
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Why does the 1st ionisation energy decrease from the 9th period to the 10th period
I’m currently looking at the ionisation energy chart within my chemistry textbook and while I know that there are not really meaningful periodic trends within transition metals, generally the ...
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Are Fajans rules relevant to melting and boiling points of alkali metal hydrides?
Among LiH, NaH, KH, RbH, CsH the one with the highest melting point is LiH, and it keeps on decreasing till CsH. The reason for this in my textbook is that the size of cations keeps on increasing down ...
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I was told that Lithium and group 2 bicarbonates does not decompose on heating.Group 1 bicarbonates does decompose except lithium
But in some sources it was explained that stability of group 1 bicarbonates increases down the group.If it is true then how does lithium bicarbonate does not decompose ?.Can anyone please tell me ...
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Upon what does the half life of a nuclide depend on? [duplicate]
Nuclide half-lives seem to be apparently random, except for the fact that heavier elements are typically radioactive and lighter ones stable. Is there any factor that can predict the half life of a ...
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Why aren't other elements with valence 6s electrons liquid like mercury?
I found out that mercury's 6s electrons undergo relativistic effects that make their pull to the nucleus greater, which makes it so that they can't bond with other atoms of mercury to form a solid. ...
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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 ...
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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 ...
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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....
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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 ...
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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 ...
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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)...
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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 ...
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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 ...
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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 ...
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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 &...
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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 ...
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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 ...
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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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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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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-...
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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 ...
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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 ...
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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 &...
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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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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?
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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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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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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Confusion 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 ...
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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 ...
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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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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 ...
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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. $r_\ce{Li+}<r_\ce{Na+}<r_\ce{K+}$...
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