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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469 views

Elements in the lanthanide and Actinide series [duplicate]

How many elements are there in lanthanide and Actinide series? My big doubt is does the 57th element Lanthanum and 89th element Actinium include in it? In some periodic table the entire 57-71 is ...
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Why do the d suborbitals start at 3d instead of 4d?

Why do the suborbitals for d start at 3 instead of four? It is in the fourth row on the periodic table and all other suborbitals start according to the row on which they are located except for d. Why ...
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1answer
611 views

Why doesn't D block contraction affect the other P block groups 14 15 16 etc

Usually we come across anomalies in the trends of periodic properties for example the size [Atomic radius value from Raymond Chang Chemistry 9th Edition] of Gallium (135 pm) is smaller than Aluminium (...
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382 views

Should I provide a citation for atomic masses?

I am writing my first lab report ever, and the handbook I was given did not say anything in particular about this issue. I will use the atomic masses for my calculations and I am not sure if I should ...
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What do you chemists need from a periodic table? [closed]

I am developing a website and later on an app with the periodic table. The reason I started was that I thought almost all the other periodic tables was awfully ugly. I do not only want to make it a ...
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1answer
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Quickly deduce block (s, p, d …) from atomic number [closed]

A question from previous year papers of IIT JEE. There's not enough time to write the electronic configuration in the exam. Please suggest a quick, objective approach.
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Non existence of B3+ in solution [closed]

I read that B3+ ions do not exist in aqueous solution, because hydration energy cannot compensate for the sum of first three ionisation energies. This leads me to the following questions: If boron (...
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2answers
10k views

Find atomic number given the group and period [closed]

I want to find the atomic number of an element in a short way, when I know the exact group and period of that element. For instance; there is a question in our textbook to find the atomic number of ...
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1answer
245 views

Are halogens a further classification of non-metals, or are they another group themselves? [closed]

I've searched many pages in the internet, and many just classify halogens (Grp 7A) as non-metals. However, my teacher classified them as another group in the periodic table, and when asked which ...
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1answer
82 views

Do the spins of outer orbitals block measurement of spin of inner orbitals?

Do the outermost s1 and s2 electrons block an outside observer from measuring the larger inner group orbitals for elements heavier than Nitrogen (for instance, would Chromium's 4s1 electron or ...
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135 views

Halides in s-block elements [closed]

What is the reason behind the following statement: The $Δ_fH^\circ$ for the fluorides become less negative as we go down the group while the reverse is true for chlorides, bromides and iodides.
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1answer
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On the periodic table: Why are groups of elements organized by 'letter' [duplicate]

Why are the groups of elements on the periodic table organized into areas represented by the letters s,p,d,f,g, and h? What does this mean?
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Mendeleev's predictions

While studying about Mendeleev's periodic table in my textbook( class 11 NCERT chemistry), I have studied that Mendeleev has predicted some elements like Eka-boron(scandium), Eka-Aluminium(Gallium),...
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2answers
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Why are metalloids found in a zig-zag line on the periodic table

I am confused about the zig-zag pattern of metalloids in the periodic table. Why are metalloids arranged in a zig-zag line? Can anyone answer my question?
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What proof is there that the “Island of Stability” exists?

Often I see people talking about an "Island of Stability" existing for super-heavy elements on the periodic table, but I don't see any reason to thinks this exists? Surely the heavier you go the more ...
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1answer
338 views

Why group 13 elements don't show +2 as their major oxidation state?

These are the things I understand: 1) Group-13 elements show +1 and +3 as their major oxidation states(OS). 2) The general configuration of G-13 elements is $ns^2$ $np^1$. 3) In the ...
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Trends in Slater's constant

I am aware of the various Slater rules to calculate the effective nuclear charge, $Z_\mathrm{eff}$ However, how can I decide the order in which the orbitals 2s, 3s, 3d, 3p, 4d, and 4f stand when ...
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1answer
789 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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What organizational methods pre-date the Periodic Table?

Dmitri Mendeleev noticed patterns in elements which allowed him to design the periodic table which ultimately led to the modern periodic table. How were elements organized before this? Was there any ...
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1answer
172 views

Why don't elements having the same valency as Carbon bond so readily?

I haven't been in touch with Chemistry as a subject of study for several years now. Still- if I remember correctly, Si, Ge, Sn, Pb all have same number of electrons as Carbon in their outer orbits. ...
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1answer
279 views

Good collection of images showing periodicity of the Table?

Mendeleev's recognition of the periodicity of atomic trends was a milestone of human understanding, the detection of a pattern in what had appeared to be chaotic data. I think the significance and ...
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Comparing electronegativities of aluminium and gallium

If I were to compare the electronegativities of Al and Ga, shouldn't I be saying that the electronegativity of elements (in general) decreases down the group, I say this by thinking of the position of ...
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Bond Energy in P-O , S-O , Cl-O

My text says that Bond energy between P-O , S-O , Cl-O follows the trend P-O < S-O < Cl-O. But I think it should be a reverse of what's given because more the electronegativity difference ...
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1answer
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What is the difference between metaphosphoric acid and phosphonic acid?

Are metaphosphoric acid and phosphonic acid the same? I have been told that they're same BUT the structures online are different. Metaphosphoric acid has formula: $\ce{(HPO3)_n}$ phosphonic acid ...
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Electronic configuration of uranium

I read that the electronic configuration of uranium is [Rn] 5f³ 6d¹ 7s² . Given that the subshells fill in the order 5f --> 6d, why is the 5f subshell only partially filled? Why do electrons fill ...
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1answer
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Why is UuX used as a symbol for unnamed elements on the periodic table?

Until recently, the last few elements on the periodic table had the chemical symbols (now they have formal chemical symbols!): Uub, Uut, Uuq, Uup, Uuh, Uus, and Uuo Why did they have these temporary ...
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absorption spectrum of water at different wavelengths [closed]

I know I can get the visible absorption spectrum of water https://en.wikipedia.org/wiki/Water_absorption But how does one go about getting and testing what the absorption spectrum is for a glass of ...
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2answers
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Why are group 1 elements called alkali metals and group 2 elements are called alkaline earth metals?

I was studying the periodic table. My teacher said that Group 1 elements are called alkali metals because their oxides are soluble in water and group 2 elements are called alkaline earth metals as ...
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547 views

Why magnesium has the lowest melting and boiling point in its group? [duplicate]

It is written in the third point ( shown in the picture) that presence of d orbitals results in stronger metallic bond. 1) We check the strength of metallic bonding to compare the melting and boiling ...
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Do non-English speaking countries use the same element symbols?

The question does sound pretty absurd, but hear me out first. The Periodic Table of the Elements, as I know it, is supposed to be a common standard adopted by the global scientific community. However,...
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1answer
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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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Does organic chemistry somehow defy the periodic table? [closed]

My physics lecturer was introducing the idea of what a Theory of Everything was, and said something like this: Other sciences have their own theories of everything too, fundamental axioms from ...
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1answer
186 views

Is there any specific formula to find periodic table periods and valence electrons

I am developing a program, that uses a lot of stuff related to the periodic table. As of now, I am making a part of it the determines the period and family. I know that both of those have to do with ...
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Why is Promethium the only radioactive Lanthanide?

Why is it that only Promethium (Pm) is the only radioactive lanthanide? I was trying to figure out what percentage of all radioactive elements in the Periodic Table the f-block accounts for, when it ...
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1answer
395 views

Periodic table and p block elements

I have two questions: It's said that in p block there's gradation in physical and chemical properties of elements. What is meant by this statement? Why are the different blocks named s, p, d and f?
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To which block of the periodic table does helium belong?

According to quite a few books I have read, helium belongs to the p-block with reasoning along the lines of "it's an inert gas, so let's clump it together with other noble gases which are in the p-...
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1answer
301 views

Electronic configuration and the periodic table

I came across the following question: If each orbital can hold a max. of 3 e– what is the number of elements in the 4th period of the periodic table? I was unable to even start the thought ...
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1answer
246 views

Why is the lanthanide element Thulium malleable?

I was doing some research about Thulium and every website says that it is malleable, but doesn't explain why. What chemical properties does Thulium possess which makes it malleable?
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Why does electronegativity generally increase across a period? [duplicate]

I've been doing some research and the only answer I seem to be getting is that the increase of protons means electrons are more attracted to the atom. I thought though it was because as you go ...
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1answer
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Why isn't 4s1 electron of Chromium the last electron?

I know that to aid the symmetry of singly occupied orbitals one electron jumps from 4s orbital to 3d orbital thus giving Chromium the configuration 3d5 4s1. But my question is, when we're evaluating ...
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Relation of Boiling Point and Melting Point with the reactivity of an element

When we look at the trends of periodic table, there is an interesting correlation to be noticed. Along a period, when we look at the trends in reactivity of an element( Both due to electropositivity ...
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Table of expanded electronic structures of atoms

Where can I find the table containing expanded electronic configurations for atoms in the periodic table, showing how outer electrons are distributed between different atomic orbitals? I really just ...
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1answer
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Why are there 3 columns in Group VIII of the Periodic Table?

I'm currently reading in-depth about the layout of the Periodic Table, and I wondered why the table has 3 columns in its Group VIII: As I understand, this is an old notation of the table, now ...
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1answer
175 views

What properties of later elements are predicted by scientists? [closed]

Though scientists have predicted up to element 172 (unseptbium) what properties do they predict any elements later on the extended periodic table may have?
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1answer
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Why do some periodic tables have 18 groups while others have 8?

In school I have been taught about the periodic table with 8 groups, representing the number of electrons in the outer shell (with exceptions). But online almost all I can find is periodic tables with ...
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1answer
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2nd Electron Affinity of halogens

I have seen questions regarding EA but they were all about the 1st EA so this question is not duplicate. I came across a statement which goes like "2nd EA of halogens is almost zero". How is this ...
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What is the correct order of chemical reactivity in terms of oxidising property for the following elements: F, Cl, O, and N

This is a textbook question. I am confused as to which factors i should consider while sorting out these elements. If I take electron gain enthalpy, then Cl should be greater than F, but if i consider ...
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1answer
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Why can mercury(I) exist, but not zinc(I)?

Mercury shows variable valency while zinc does not. Its electronic configuration is $\ce{[Xe]\:4f^14 5d^10 6s^2}$. So it can donate the $\ce{6s^2}$ electrons and should only be able to form $\ce{Hg^2+}...
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Deviation of Ytterbium from general trend

What is the reason for deviation of ytterbium from the general trend of lanthanides in terms of hardness, melting point, density etc.?
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Anomalous Electronic Configuration of Thorium

The electronic configuration of thorium ($Z=90$) is $5\mathrm f^0 6\mathrm d^2 7\mathrm s^2$. But, according to the aufbau principle, the electrons should first enter the $\mathrm f$ subshell and not ...