Questions tagged [periodic-table]

This tag should be applied to questions about the layout, history and interpretation of the periodic table, not to questions relating to specific elements or trends within the table. For these, the tags 'elements' or 'periodic-trends' should be used where appropriate.

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What is the periodic trend of Zeff across the periodic table? [duplicate]

So I was watching a vedio of this topic on youtube. They didn't explained it in detail that what what happens when we go from left to right or top to bottom. And why the Z eff of Na=K=Rb=Cs And I'm ...
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What is the periodic trend of effective nuclear charge across the periodic table? [closed]

So I was watching a vedio of this topic on youtube. They didn't explained it in detail that what what happens when we go from left to right or top to bottom. And why the Z eff of Na=K=Rb=Cs And I'm ...
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percent Abundance [closed]

On a planet Q, there is a metal Y with an atomic number of 48. Y has three isotopes Y-124, Y-128 and Y-138. From analysis, it is known that the abundance of Y-138 is 4 times more than Y-124. The ...
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Transition metals with closed shells

From wiki page about valence electrons: An atom with a closed shell of valence electrons (corresponding to an electron configuration $s^2p^6$ for main group elements or $d^{10}s^2p^6$ for transition ...
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Discordance in periodict tables, polonium and astatine as semimetals [closed]

I searched periodict tables on the internet. I realized that some show polonium as semimetal others show astatine as semimetal. All periodict tables say that there's seven semimetals. Only those ...
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What's the decreasing reactivity order of F, Cl, O and N? [closed]

The answer given in my textbook is F>O>Cl>N. The reason given is the decreasing order of oxidising nature. My question is, if we use the concept of "more negative the electron gain ...
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How does electronegativity affect pπ-pπ bonding? [closed]

I have found in a book that, The elements in the 2nd period belonging to the p-block(e.g. Carbon, Oxygen) shows comparatively high tendency to form pπ-pπ multiple bonding with same atom or different ...
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Why can’t lanthanum through lutetium and actinium through lawrencium all be in group 3?

In 2015, IUPAC established a task force to “deliver a recommendation in favor of the composition of group 3 of the periodic table.” Not much about their decision-making process has been made known to ...
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1answer
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How would someone in 1917 describe elements 43, 61, 72, 75, 84, 85, 87, 89, and 91? [closed]

https://books.google.com/books?id=aaELAAAAYAAJ&printsec=frontcover#v=onepage&q&f=false Notice the list of elements on pages 62–63. It includes a short description of each element's "...
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Why the melting point increase up to arsenic and then decrease down the group 16? [duplicate]

I am already google this but can't find the answer that staisfy me. I know down the group, mass and atomic size increase which result in increase in van-der-waal forces. But in group 16 the trend is ...
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Find the Ionisation Potential and Electron affinity of X

$N_0/2$ atoms of $X_{(g)}$ are converted into $\ce{X^+_{(g)}}$ by energy $E_1$. $N_0/2$ atoms of $X_{(g)}$ are converted into $\ce{X^-_{(g)}}$ by energy $E_2$. Hence ionisation potential and electron ...
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Why is the ionization energy of radium higher than barium? [duplicate]

The ionization energy of radium is higher than barium. The reason provided is that occurs fue to lanthanide contraction. But, Radium isnt a member of lanthanide series. How come we say that lanthanide ...
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67 views

Contradiction of general rules of bond character [closed]

The rules the ionic character of metal halides of halogens is given in order $\ce{MF > MCl > MBr > MI}$. While judging polarisability we say that a compound that has large cation and small ...
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How can an element have two outermost shells incomplete? [closed]

As I read my book, I saw its written that the Transition metals have two outermost shells incomplete. But , as I had read earlier, that shells are filled in stepwise manner. So how is this possible? ...
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1answer
545 views

How to determine the number of electron in a shell [duplicate]

My textbook has been mentioned that the maximum number of electron in a shell is 2n² and the octet rule. It has also said that period number signifies the number of electron shells of an element and ...
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1answer
77 views

Determining electronic configuration [closed]

One writes the electronic configuration in terms of shells, spdf subshells, orbitals, and spin of electrons. There are exceptions to principles we know. How does one confirm that the way of writing is ...
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471 views

How did Mendeleev know elements from compounds or mixtures?

I read that Mendeleev initially thought didymium was an element, but it was actually a mixture. How did he know the rest of the chemicals in the periodic table were elements and not compounds, ...
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1answer
75 views

Lewis structures and chemical-compound formulas [closed]

In the Lewis structures listed below, M and X represent various elements in the third period of the periodic table. Write the formula of each compound using the chemical symbols of each element: a. b. ...
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What is the correct electronic configuration of darmstadtium?

Some of the places, the electronic configuration of darmstadtium ($\ce{Ds}$) is given as $\mathrm{6d^9 7s^1}$ while at some other places, it is $\mathrm{6d^8 7s^2}$. Which among the two is correct?
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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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Why there is no position of H and He in Lothar Meyer's curve?

I see Alkali metals occupy the peak points. $\ce{H}$ is not an Alkali metal. There's no $\ce{H}$ in the graph. So no point before $\ce{Li}$. Inert gases occupy place on the ascending portion of graph. ...
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1answer
246 views

Why is ionization energy of indium less than gallium?

In group 13 we observe an irregular trend in ionization energy: B > Tl > Ga > Al > In. Gallium has a filled 3d subshell, but indium has a filled 4d and 3d subshell. Thus it should have more poor ...
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Which orbital participates in bonding of d and f block elements as these are never the outermost orbital?

For example: Yttrium: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d1 5s2 The outermost orbital is the s-orbital but d-orbital is unfilled. How does overlap of orbital take place in YCl3 as d-orbital is beneath ...
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Why is platinum denser than gold?

The atomic masses of gold and platinum are 196.96657 u and 195.084 u respectively, meaning that (on average) an individual gold atom is heavier than an individual platinum atom. At the same time, the ...
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Difference in a array of probability density plots for the electron in its lowest-energy states of Hydrogen atom [closed]

Dynamic Periodic Table If you visit Dynamic Peridic Table, You will notice that for n=4 l=3,2 m=0,0, and n=2,l=1, m=0 there is a difference in the probability density plots for electron in its ...
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241 views

Comparing Electron affinity and electron gain enthalpy at 0 K

In my book it is given that first electron gain enthalpy is greater than second for elements. Should we compare the magnitudes in such cases or the actual numbers with signs? Does the same comparision ...
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1answer
263 views

Why aren't Boron and Aluminium assigned to group 3 of periodic table? What determines the group? [closed]

I've been curious about this 3D representation of the periodic table "Mendeleev's Flower" and was trying to study it, wondering if it reveals any regularities that are not obvious from classic ...
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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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Is “family” synonymous with “group”? [closed]

Is using the term "family" strictly correct when we mean a group of the periodic table or is it just in general use (and should perhaps be discouraged in favour of using "group" exclusively)? At my ...
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919 views

What do you mean by “periodic” in the periodic table? [closed]

Modern periodic law states: “The physical and chemical properties of the elements are periodic functions of their atomic numbers”. But I don't think this is so! (Forgive me for my stupidity. But ...
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How to determine the chemical state of a reactant or product in a chemical equation?

I am asked this question: Write a balanced equation, including state symbols, for this reaction: $\ce{calcium + hydrochloric acid -> calcium chloride + hydrogen}$ I answered this: $\ce{Ca(s) + ...
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1answer
517 views

The number of transition elements

I searched in the internet but most of them said that there are 38 transition metals. But our text book says that group 12 or the group of zinc CAN'T BE COUNTED as transition metals. Which already ...
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1answer
197 views

Structure of the periodic table

The periodic table I understand is arranged by order of increasing atomic number after Henry Moseley's X-ray experiment. But I also learned that the periodic table also has its shape due to the ...
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1answer
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Effective nuclear charge and Ionization energy

A common reason given on why 3rd ionization energy > 2nd > 1st is because of increasing effective nuclear charge. As per my book $Z_\mathrm{eff}$ = Atomic number $-$ Number of inner electrons. Now ...
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1answer
524 views

The boiling points of Alkali metal group

As I know, the melting points of Alkali metals decrease down to the group due to decreasing of the energy of the metallic bond. But according to my understanding, after it has become to liquid the ...
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1answer
196 views

How would one determine an element simply by looking at its binding energy?

I am self studying MIT OCW chemistry 5.111 2014, one of the lecture questions states the following: Consider a neutral atom with 8 distinct electron binding energies: −14 eV, −28 eV, −94 eV, −218 ...
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Electrons and Atomic Mass

Is the mass of electrons covered when talking about atomic mass. For example, the mass of Carbon is $12.011\space\text{amu}$. If this is including the mass of electrons (assuming the atom is neutral) ...
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1answer
402 views

Why does Calcium have a higher ionization energy than Aluminium?

Given their places on the periodic table I'd assume Aluminium has a higher ionization energy, because it has fewer energy levels, and is on a "righter" row on the periodic table, but in reality it is ...
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1answer
2k views

Comparison between van der Waals radius and metallic radius

I was reading about different types of atomic radius. It was written that if any atom can possess all the three types of radius, then van der Waals radius will be greater than metallic radius. However ...
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Why is atomic number unique? [closed]

We all know that atomic number of an atom is "unique" just like fingerprint. And no two elements can have same atomic number. But how can we be So sure that no two elements can have same atomic number?...
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Why is the product of the reaction “Bi + O2” Bi2O3 instead of Bi2O5?

I am stuck on a homework question that states: A piece of solid bismuth is heated strongly in oxygen. The answer key states the answer as $\ce{Bi + O2 → Bi2O3}$. However, it is to my understanding ...
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1answer
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The reaction of Group 14 to get its full shell

I was learning about group 14 of the periodic table and in the course, on Alison (link at the bottom), it said a reaction of the elements in group 14, they use group 4, would consist of sharing ...
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Why is Thorium (At. no. 90) an f-block element at all?

Being an exception of the Aufbau principle, Thorium has an electronic configuration of $\ce{[Rn]}\mathrm{7s^25f^06d^2}$ instead of the expected $\ce{[Rn]}\mathrm{7s^2 5f^2 6d^0}$. Two other elements, ...
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686 views

Why does period 3 of the periodic table contain 8 elements instead of 18?

Period 1 of the periodic table contains 2 elements ($1s^1$ and $1s^2$). Period 2 contains 8 elements ($2s^1$, $2s^2$, $2p^1$, $2p^3$, ..., $2p^6$). By the same argument, period 3 might contain 18 ...
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1answer
328 views

Why is the valency of the Calcium (Ca) Bohr model, set to 2 electrons, instead of 1 electron for stability? [duplicate]

This is an Ascii table for the elements on the 4th period (row) of the periodic table, and distribution of electrons in each orbit. ...
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124 views

Predicting atomic weight and density of calcium [closed]

I have a question from school: Assuming that the element Ca had not been discovered, predict using the properties of the known element surrounding Ca its own properties such as its atomic weight ...
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1answer
204 views

What is the electronic configuration of La⁺? [closed]

Second IP of La is most likely to second IP of which element: (1) Be (2) Ba (3) Ca (4) Zn The given answer is calcium. I don't understand if the 6s electron or the 5d electron leaves on ...
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1answer
6k views

Effective nuclear charge of oxygen atom (O) vs oxygen anion (O2-)

The size of an anion is greater compared to its parent atom because former's effective nuclear charge is lesser than that of latter. I found on wikipedia that the effective nuclear charge can be ...
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1answer
2k views

why lithium is less reactive than sodium? [duplicate]

Lithium lies above sodium in a group and is also smaller in size. According to periodic trend reactivity decreases from left to right in period and down the group.
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Definition of early vs. late transition metal

Is there an accepted definition of an early or late transition metal? I think the late transition metals start at Group 8 (including Fe), but others have said Fe is not a late transition metal. I'm ...

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