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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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 ...
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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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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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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 ...
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Variation in atomic radii of elements in different blocks?

If we look at the values for the atomic radii (look at the table here), we can see that they rapidly decrease across the period initially. Looking at the second period, The graph is pretty steep ...
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Periodic trends: why is effect of protons greater than electrons?

Why is it that adding protons has a greater effect than electron-electron repulsion on periodic trends like atomic radius and ionization energy (assuming # of shells constant)? It seems that if ...
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Does there exist any relation between metallic property and oxidation potential?

I was having a revision on periodic table I was thinking about different properties I could connect most of I could not connect metallic property and oxidation potential .
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lanthanide contraction

"The Lanthanide Contraction refers to the fact that the 5s and 5p orbitals penetrate the 4f sub-shell so the 4f orbital is not shielded from the increasing nuclear change." First, 5s and 5p are ...
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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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216 views

Electronegativity of heavier elements of Group 15

While reading about p-block I got to know that in Group 15 elements electronegativity value decrease down the group but amongst the heavier elements difference is not that much pronounced. I ...
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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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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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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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Is strontium more metallic than sodium? If yes then why?

I got an MCQ in my examination, "Which one of the following is more metallic?" and the options were Sr, Na, Be or Aluminium. I know that sodium is more metallic than Be or Al but my mind stuck on ...
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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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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 ...
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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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Boiling Point trend

Why does group 13 and 14 show reverse the trend of boiling point? In other groups, boiling point increases down the group but here it decreases.
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Trends in the covalency of bonding across the transition metals

I am under the impression that the covalent character in the bonding of transition metal compounds increases across a group; in fact I think this is why they're called transition metals (a transition ...
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Why is ionisation energy of bismuth lower than lead?

Why is ionisation enthalpy of Bismuth less than that of Lead for it just comes after the latter in periodic table? First ionisation energy of bismuth is 703 kg/mol while that of lead is 715 kg/mol. I ...
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Why there is an exception in melting and boiling point in p block?

Why is the boiling point and melting point of 15th group and 16th group has an exception? We know that as molecular mass increases boiling point and melting point also increase. So, down the group 15 ...
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Why does sulfur exist as octasulfur? [duplicate]

Sulfur belongs to the same group as oxygen. Then why oxygen exists as an $\ce{O2}$ molecule while sulfur exists as $\ce{S8}$ molecule? What's the chemistry behind this?
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How to explain the periodic trends in boiling points in groups?

Observing the trend of boiling points of the compounds listed, choose the appropriate terms to fit into the blanks: \begin{array}{lr} \text{Compound}& \text{boiling point}\\\hline \ce{H2Te} &...
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What is the reason for the different solubility of silver halides in ammonia?

According to my knowledge, I know that $\ce{AgCl}$ dissolves in dilute ammonia, $\ce{AgBr}$ dissolves in concentrated ammonia and $\ce{AgI}$ does not dissolve even with concentrated ammonia. What is ...
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Order of second iozination energies of lithium,berillium,neon,carbon and boron?

The correct arrange of them is like this: Be < B < Li ... But why? Li will have the greatest IE2 (second ionization energy) because that will involve removing a core electron, but what I am ...
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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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Why does oxygen in OH have an oxidation state of 2-?

I am watching videos on Khan Academy in order to go over redox reactions (a really weak area for me.) In Sal's video, "Oxidation state trends in periodic table" at 7:10, he says: If you had to ...
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Why are alkali salts so soluble?

There's a certain solubility rule stating all carbonates, phosphates and hydroxides are insoluble unless mixed with hydroxides or alkali metals. Why is this? What makes the alkali metals so special?
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Ionization energy of neon vs its cationic counterpart

Which requires more ionization energy: $\ce{Ne}$ or $\ce{Ne+}?$ It seems to me like it should be neon because of noble gas configuration, but the answer given is $\ce{Ne+}.$ Does this anything to do ...
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Why is the first ionisation energy of a sodium cation bigger than that of a neon atom?

I understand that the 1st ionization energy gets bigger for elements along a period from left to right and along a group from down to up. But why is the 1st ionization energy of $\ce{Na+}$ bigger ...
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Determining the group number of an element from its successive ionization energies

The successive ionization energies of an unknown element X are: 1st - 9534; 2nd - 11790; 3rd - 13683; 4th - 15309; 5th - 16458. To what group number does X belong? There aren't any significant ...
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How is the oxidation number related to the group number?

If an element $\ce{X}$ forms the highest oxide of the formula $\ce{XO3}$, then it belongs to group: A) 14 B) 15 C) 16 D) 17 How is an oxidation number of an element related to its group? I ...
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Why the ionization energy of Au is more than that of Cu?

As we go down the group from 3d to 5 d, size increases. Vanderwaal radius of Cu and Au is 140pm and 166pm respectively. Since Cu is smaller in size, ionization energy of Cu must be greater. Then ...
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Does increasing electronegativity imply more covalent character?

If there is a larger electronegativity difference between two atoms, shouldn't the compound be more ionic? In an explanation of the diagonal relationship, it states that "on moving across the period, ...
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Periodic Trends of Zeff and Electronegativity

The effective nuclear charge $Z_\mathrm{eff}$ increases from left to right and from top to bottom. Can you explain why it increases from top to bottom? Also can we explain the periodic trend of ...
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Why is ionization potential considered a periodic property?

Why is ionization potential considered a periodic property??? A periodic property is a one which appears at regular property But we see that every element has some kind of ionization potential
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Pair of analogous periods on the periodic table

On the periodic table, period 2 and 3, 4 and 5, 6 and 7 and so on have similar blocks, identical length and groups. What are such pairs of analogous periods called?
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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, ...
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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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908 views

Last electron of a transition element

The electronic configuration of nickel is Ni: [Ar] $3d^84s^2$ Here, while writing the configuration, we fill the 3d after 4s.Hence the 28th electron enters the d orbital. But $\ce{Ni+}$: [Ar] $...
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Pattern to determine the maximum ionic charge for transition elements?

According to my textbook, main group elements follow a simple pattern when determining their maximum ionic charge. The maximum cationic charge is always equivalent to their main group number (group ...
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How do atomic radius and nuclear charge influence ionisation energies?

This is actually a multiple choice question. Why is the first ionisation energy of neon higher than that of fluorine? A: Fluorine is more electronegative than neon B: Neon has a complete octet, but ...
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Oxidation state of group 2 elements

I have came across the following statement : "the oxidation state $+II$ is stable for the elements of the alkalin earth metals" , the same is true for the elements of the first group , i've looked for ...
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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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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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Atomization enthalpies of transition elements

So, my book says that transition elements have higher enthalpies of atomization than other elements (say s- or p- block) because of stronger metallic bonding, primarily due to large number of unpaired ...
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How to determine the valence electrons of D-block elements in their mono atomic form?

For s and p block we can determine the valence electrons easily,but what about d-block elements. How to determine their valence electrons?
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Why doesn't core charge increase down a group? [closed]

Atomic radius increases down a group because the electrons feel a lesser attraction to the positive nucleus (due to shielding from inner shells). Why then, doesn't core charge decrease seeing as core ...
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Why is the strontium ion smaller than the potassium ion? [closed]

The ionic radius of the $\ce{Sr^2+}$ ion is $\mathrm{132\,pm}$, while the ionic radius of the $\ce{K^+}$ ion is $\mathrm{152\,pm}$. Why is this the case? I would have thought that since $\ce{K^+}$ has ...
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Why does the electron affinity increase become more exothermic down group 2 and group 5?

It is generally true that the electron affinity becomes less exothermic down a group, because of the increase in atomic radius. There is a well-known exception that the electron affinity of Cl is ...