Trends which are observed in the properties of elements as you move along the periodic table in a given direction.

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Relation Between Degree of Hydration and Electropositivity

Why are salts of strongly electropositive elements less heavily hydrated in aqueous solution than the those of less electropositive elements? Shouldn't it be the other way round as the salts of ...
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98 views

Diagonal relationships in the Periodic Table

I have often wondered about diagonal relationships between elements on the periodic table, and the most often cited explanations revolve around charge-density considerations. But other than that, ...
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Electron affinities of the chalcogens and halogens

Here are the electron affinities of the 17th and 18th groups. The general trend for electron affinity down the group is that it decreases because of the increase in atomic radius.The exception of ...
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50 views

Anomalous trends in ionization energy

I want to address two exceptions in the trend of ionization energy across the period, that are causing me problems: Taking the second period as an example : The two exceptions from the general trend ...
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446 views

Is there a function to approximate atomic mass from the atomic number?

The product of $2Z$ generally approximates the value of $m_\mathrm{a}$ of atoms that comprise relatively few protons. Whereas, the product of $2.5Z$ generally approximates the value of $m_\mathrm{a}$ ...
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42 views

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 first period, The graph is pretty steep ...
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20 views

Available orbitals for promotion

I am under the impression that elements from the third period onwards can promote electrons into d orbitals to form hybridised orbitals. Why would an element in the third period promote an electron to ...
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187 views

Dipole Moment Anomaly in Fluorine and Chlorine Compounds. What factors affect them?

I was checking dipole moment orders, and came across a very peculiar result: Methyl fluoride has lesser dipole moment than methyl chloride, but hydrofluoric acid has more dipole moment than ...
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36 views

What type of bonding occurs in isolated silicon?

Would isolated silicon engage in network covalent bonding as quartz does or would it engage in a different kind of bonding? Would germanium display similar qualities? *I am asking what is the bonding ...
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53 views

Why does ionization energy increase as we go from left to right in a period?

Why does ionization energy increase as we go from left to right in a period? In my textbook, the explanation is as follows: "This is consistent with the idea that electrons added in the same ...
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89 views

Why are inert gas (especially Xenon) compounds powerful oxidizing agents?

I am curious as to why compounds with inert gases, such as $\ce{XeF4}$, $\ce{XeF2}$, and $\ce{XeO3}$ are considered powerful oxidizing agents. I would attribute the phenomenon to the highly oxidized ...
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98 views

Why is arsenic more chemically similar to phosphorus than is nitrogen?

Why is arsenic more chemically similar to phosphorus than is nitrogen (to phosphorus)? I thought that it may be because both phosphorus and arsenic have d orbitals (albeit one has one that is filled ...
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52 views

Why is the melting point of TiCl4 lower than TiCl3

I was wondering why the melting point of $\ce{TiCl4}$ was below that of $\ce{TiCl3}$ The melting point of the former is $\ce{-25 Celsius}$ whereas the latter is $\ce{425 Celsius}$ . Thanks!
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105 views

Second ionization potential of Gadolinium

I notice that Gd has a second ionization potential which is significantly higher than would be expected from the general trend in the lanthanides (see this paper p. 945 for a graph). What is the ...
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123 views

Why does the second electron affinity has an opposite sign of the first one?

Most of the first electron affinities are positive, therefore the second ones are negative, and vice versa. but why? SPECIALLY WHEN THE FIRST ELECTRON AFFINITY IS NEGATIVE .. WHY THE SECOND ONE IS ...
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36 views

How adding one more electron increases the ionization energy?

elements of group 6A, compared to 5A, requires less ionization energy due to the paired electrons of 6A but a question arises... why group 7A,compared to group 6A, requires more ionization energy in ...
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149 views

Effect of effective nuclear charge increase on the stabilization of 2s and 2p orbitals

Are 2s or 2p orbitals more stabilized when going from left to right in the period? There are good arguments for both possible answers: 1) 2p orbitals are more stabilized because they penetrate less ...
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21 views

How to rationalise the trend in the covalent radii of the transition metals?

Why do the covalent radii of transition series decrease at the start rapidly, then become almost constant and at the end of series begin to increase from left to right in periodic table?
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97 views

Basicity of Group 15 hydrides [duplicate]

Why does the basicity of Group 16 hydrides ($\ce{NH_3,~ PH_3,~ etc}$) decrease down the group ? I know that its Lewis Base nature due to the lone pair but wouldnt the more EN element be less ...
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280 views

Memorizing the periodic table

Several people have said that the key to understanding chemistry is through memorizing the periodic table. I want to ask if there is a simple technique to learn it, or if I just have to remember ...
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44 views

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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37 views

How does absence of nd orbital in Oxygen affect its valency?

The original question was 'Oxygen exhibits Oxidation state -2 to +2 but other elements of grp 16 exhibit only +2,+4,+6. Explain Why'. In the solution given i can't understand meaning of this line 'It ...
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1answer
314 views

Why do screening effect decreases due to d-orbital?

I am currently learning about p-block elements. In that in 13th group from Boron to Aluminium atomic radii increases. From Aluminium to Gallium atomic radii decreases. From Gallium to Indium atomic ...
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151 views

What is the reason behind choosing the specific elements used for the synthesis of heavier elements?

Attempts to synthesize still undiscovered elements This is derived from the wiki page: "extended periodic table" and is one of the many examples d or f block elements are used in ...
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63 views

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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320 views

Why is Osmium the densest known element

Why is Osmium so dense, Even if we have more heavy elements post to it.
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175 views

Factors of London Forces

In class we learnt that the London forces become stronger as the relative molecular mass increases. Not just as in organic chemistry but in things like the halogens. However, as I understand, the ...
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804 views

Periodic trend in difference of energy between the s and p orbitals

Why does the difference of energy between the 2s and 2p orbitals of the second period elements increase with increasing atomic number? Does this difference increases by moving down a group, e.g. is ...
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307 views

Outermost electronic configuration of f block elements

I have a doubt regarding the general outermost electronic configuration of f block elements. Why is it $(n-2)f^{1-14}(n-1)d^{0-1}ns^2$. The only exception i thought to this formula was thorium ...
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76 views

Can you calculate the properties of a substance based soley on its atomic properties?

I'm trying to write some software that I can use to determine, roughly, what the physical properties of a pure substance are. I know I could just use a database of the known properties of each ...
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552 views

What's the order of oxidising strength of the oxyacids of Chlorine?

What I have been told is that the acidity of the four oxyacids of Chlorine increase in the order $\ce{HOCl} < \ce{HOCl2} < \ce{HOCl3} < \ce{HOCl4}$. I have also been told that the oxidising ...
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409 views

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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122 views

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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243 views

Why is the size of Al3+ less than that of Li+?

Why is it so that the size of $\ce{Al^{3+}}$ is lesser than $\ce{Li+}$? I'm a bit confused about this one as the aluminium(III) ion is composed of 10 electrons and 13 protons, while the lithium ...
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3k views

Why does bond angle decrease in the order H₂O, H₂S, H₂Se?

I know that bond angle decreases in the order $\ce{H2O}$, $\ce{H2S}$ and $\ce{H2Se}$. I want to know the reason. I think this is because lone pair repulsion but how?
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102 views

Arrange B , Be , Li in order of increasing IE2

IE2 = Second ionization energy the correct arrange of them is like this : Be < B < Li ... But why? Li will have the greatest IE2 because that will involve removing a core electron but what I ...
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867 views

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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114 views

Atomic radii of Sc,Ti and Fe,Co

The atomic radii of Sc is 162pm , Ti is 147pm , Fe is 126pm and that of Co is 125pm. Electronic configuration of Fe is (Ar)3d6 4s2 and that of Co is (Ar) 3d7 4s2. Difference of Z between them is 1 ...
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113 views

How is the oxidation number related to the group number?

How is an oxidation number of an element related to its group? I was trying to answer an homework question.The question was: If an element X forms the highest oxide of the formula XO3, then it ...
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101 views

Calculating Electronegativity of Fluorine [closed]

Calculate the electronegativity of Fluorine from the following data. EH-H = 104.2 kcal/mol EF-F = 36.6 kcal/mol EH-F = 134.6 kcal/mol XH = 2.1 How to solve? Any wiki or link to somewhere where ...
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494 views

Which is more acidic? CO or CO2?

Q1)Which of the given compounds is most acidic? $\ce{CO}$ or $\ce{CO2}$ ? How to solve(explanation)? EDIT: Q2) $\ce{BeO}$ is amphoteric while $\ce{B2O3}$ is acidic - True/False?
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351 views

Ionization Energies of Sulphur and Oxygen Anions

Which of the following are in the correct order of their Ionization Energies?(Multi-Answer Question) a) $\ce{O > S > S- >O-}$ b) $\ce{F > F- > Cl- > Cl}$ c) $\ce{O > O- ...
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Why lanthanides and actinides are shown separate from standard Periodic Table layout?

In the standard Periodic Table layout , all the elements upto 56 are in order i.e are in the same layout table. However, lanthanides and actinides are always shown separately from the layout like in ...
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478 views

Halogen Oxyacid Trend (acid strength)

Why is $\ce{HClO4}$ more acidic than $\ce{HBrO4}$? But $\ce{HCl}$ is less acidic than $\ce{HBr}$? What determines the acidity? Is it the concentration of $\ce{H+}$? If so, how do these trends develop ...
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279 views

Trends for electrical conductivity?

Which element has the greatest electrical conductivity? (A) As (B) Ge (C) P (D) Sn I am unsure of how to approach this problem. Is there some sort of trend for electrical conductivity or some ...
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332 views

For which pair of species is the difference in radii the greatest?

For which pair of species is the difference in radii the greatest? (A) $\ce{Li}$ and $\ce{F}$ (B) $\ce{Li+}$ and $\ce{F^-}$ (C) $\ce{Li+}$ and $\ce{O^2-}$ (D) $\ce{O^2-}$ ...
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627 views

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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Why does sulphur exist as $S_8$ molecule? [duplicate]

Sulphur belongs to the same group as Oxygen. Then why Oxygen exists as an $O_2$ molecule while Sulphur exists as $S_8$ molecule? What's the Chemistry behind it?
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684 views

Why is lanthanum a lanthanide and actinium an actinide?

I do know that the lanthanides start with the element lanthanum, but why? Lanthanum doesn't even have an $f$ orbital, so why isn't it considered a transition metal? It's the same way with actinium, ...
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Have there been no advances in the determination of effective nuclear charges since Clementi and Raimondi in the 60s?

Effective nuclear charge is a very important concept in chemistry, and is the basis for the qualitative explanation of many observed chemical and physical properties, including several periodic ...