Tagged Questions

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

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263 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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1answer
71 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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1answer
57 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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1answer
83 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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1answer
69 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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2answers
54 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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1answer
98 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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1answer
929 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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1answer
42 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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1answer
100 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 ...
3
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2answers
62 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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1answer
48 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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1answer
54 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 ...
0
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1answer
68 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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2answers
127 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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3answers
227 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 ...
3
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1answer
179 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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2answers
159 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) $\ce{O^2-}$ ...
2
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1answer
153 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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0answers
25 views

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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1answer
293 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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2answers
160 views

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 ...
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2answers
285 views

What is the joke that is shown in this picture?

There is supposedly a joke shown in this picture relating to periodic trends. Does anyone know what it is? And could they also explain where the elements on the eye exam came from?
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2answers
2k views

Why does electronegativity increase across a period?

What explains why electronegativity increases as you move across a period? Does it have something to do with the shielding effect of added electrons?
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1answer
110 views

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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2answers
6k views

Why does chlorine have a higher electron affinity than fluorine?

Since fluorine has its valence electrons in the n=2 energy level, and since chlorine has its valence electrons in the n=3 energy level, one would initially expect that an electron rushing towards ...
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1answer
437 views

Which is more metallic?

Which element has more metallic character - aluminium or magnesium? I know that metallic character decreases along a period(from left to right)and increases down a group. Aluminium comes after ...
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1answer
228 views

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 ...
0
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1answer
57 views

Can you determine whether a compound can form given particular elements?

Say you are given a set of particular elements, such as Dy, C, I, Er, P; is it possible to determine whether a compound exists with all of the given elements and no more? If not, is it possible to ...
0
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1answer
423 views

Why is periodicity seen in these certain properties?

I missed my lesson on periodicity so had to teach myself, and have always forgotten to ask my teacher to explain to me why these trends are seen, which, unfortunately, the textbooks don't. Density: ...
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votes
2answers
4k views

Melting and boiling points of transition elemets

The melting and boiling points of transition elements increases from scandium ($1530^\mathrm{o}\:C$) to vanadium ($1917^\mathrm{o}\:C$). They increase because as we go across the group, we have more ...
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2answers
185 views

Did Mendeleev predict the existence of neutrinos?

According to this Wikipedia page, Mendeleev originally believed that the inert gases belonged in Group 0 (to the left of the alkali metals). Thus, helium would be placed in the second period to the ...
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1answer
5k views

Why are elements on the right side of the periodic table nonmetallic and gas at room temperature?

Elements on the left side of the periodic table tend to be solid and metallic, elements on the right side of the periodic table are nonmetal and tend to be gases at room temperature, and the ...
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1answer
6k views

Why does the melting point get lower going down the Alkali Metal Group with increase in atomic number?

Why does the melting point get lower going down the Alkali Metal Group with increase in atomic number?
0
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1answer
123 views

Reconciling multiple inorganic properties for the purposes of learning these elements

How can I reconcile all of the chemical properties, physical properties and peculiar behaviour of metals in inorganic chemistry for the purposes of studying these systematically? It is very hard to ...
2
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1answer
2k views

Solubility of Calcium Fluoride in water

$\ce{CaF2}$ is insoluble in water, but $\ce{CaCl2}$, $\ce{CaBr2}$, $\ce{CaI2}$ are soluble. Why is this so?
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3answers
3k views

Hydrogen - its place in the Periodic Table

Why do some people say that hydrogen should be above lithium in the periodic table and others argue it should be above fluorine?
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2answers
5k views

What is charge density?

For example, Magnesium has a higher charge density compared to Sodium, therefore its metallic lattice is stronger and it has a higher melting point. Does that mean that Magnesium has more protons and ...
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1answer
188 views

Brittle d-block metal trend

I remember seeing a periodic table that had the top-left corner of the d-block shaded and marked as "brittle". If I recall correctly, the elements were $\ce{Sc,Ti,V,Cr,Mn,Y,Zr,Nb,La}$. I think (Sorry, ...
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2answers
1k views

Why are there two Hydrogen atoms on some periodic tables?

Most periodic tables only feature one Hydrogen atom, on the top of the first group. But some, like the one I was given, also show Hydrogen in the 7th group, to left of Helium. Why are there two ...
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3answers
4k views

Why do atoms generally become smaller as one moves left to right across a period?

It seems to me that the addition of electrons and protons as you move across a period would cause an atom to become larger. However, I'm told it gets smaller. Why is this?