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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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 shielding along ...
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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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Why do heavier elements have smaller specific heat values.

In the periodic table the trend is that as the mass of each element increase's the specific heat tends to go down. This seems to be counter-intuitive because if I am not mistaken as mass increase's ...
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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 Platinum is denser than gold?

I know that gold is heavier than platinum . Atomic. Mass of gold : 196.96657 u Atomic Mass of platinum: 195.084 u Also, since atomic size of gold is smaller than platinum ,it should be more ...
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How can scientists be certain that there are no undiscovered elements missing from the periodic table from hydrogen to lawrencium?

Scientists are certain that there are no undiscovered elements missing from the periodic table from hydrogen to lawrencium. How? and why?
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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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Difference in a array of probability density plots for the electron in its lowest-energy states of Hydrgen 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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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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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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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 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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Two different electronic configurations for cerium

Depending on the textbook there are two different electronic configurations stated for cerium. On the one hand $$[\ce{Xe}]\mathrm{4f^15d^16s^2}\quad$$ and on the other hand $$[\ce{Xe}]\mathrm{4f^...
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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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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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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{...
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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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Where can I find a downloadable spreadsheet of element properties?

Sorry for the FAQ, but I really don't know where to find a full spreadsheet for element properties. I mean a table that has one row for each element, and the columns are its properties, such as name, ...
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Why ionisation enthalpy of early lanthanides are expected to be greater than early actinides?

In my book Chemistry Part I (NCERT XII), a statement on p. 232 goes like this: It is evident from the behaviour of the actinoids that the ionisation enthalpies of the early actinoids, though not ...
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What is a “period” of the periodic table?

I'm familiar with the periodic table / periodic system, but I wonder why it's called "periodic" since there seems not much periodic about (there seems to be little or no predictability of which ...
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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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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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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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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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225 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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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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523 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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Is aluminium a metal or metalloid?

Aluminium is along the dark line of the Periodic Table and it is $p$-block metal. Is it metal or a metalloid? Why?
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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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What trend exists in the enthalpy change of reaction of group 2 carbonates with HCl

I am currently investigating the trends in enthalpy change of the reaction of group 2 carbonates with HCl. As per ion polarization theory there should be an upward trend in stability and thus a ...
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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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How to quickly predict the group of elements with atomic numbers 117 and 120? [closed]

The elements Z (atomic number) = 117 and 120 have not yet been discovered. In which group would you place these elements? I tried to write their electronic configurations but it was too tedious and I ...
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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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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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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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n+l rule for first member of lanthanide and actinide series

as we all know that if the value of $n+l$ is same then the orbital with lower value of $n$ will get filled first so in case of first member of lanthanide series the configuration is $(\ce{Xe})\mathrm{...
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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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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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Calling Diamond an element?

Is it scientifically correct to call Diamond an element? Carbon has a wide range of allotropes, so would it be correct to actually just call graphite, diamond etc an element. For that matter, could we ...
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Comparing the EA [duplicate]

What is the electron affinity trend for the oxygen family? I am interested in the question above. I am aware that EA of O $>$ EA of S, but what about the others? Which is having more EA: O or Se? ...
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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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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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Why does radium have a higher first ionisation energy than barium?

I'm wondering why radium appears to buck the general trend that first ionisation energies decrease as you move down a group in the periodic table: barium (the group 2 element preceding it) has a first ...
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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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How will the periodic table change due to redefinition of the kilogram (May 2019)?

The definition of a kilogram has recently been changed. What effect, if any, will this change have on data on the periodic table?
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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 semi-...