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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Are periods the horizontal numbers on the periodic table and groups the vertical numbers?

I am writing this post so that I can ensure for my upcoming SUC3U0 (Chemistry, Grade 11) course test of nomenclature is correct. It's a Review of my Grade 10 General Science Course. My teacher stated ...
Abdullah's user avatar
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1 answer
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Why does Cr have higher melting point in the 4 period among the transition metal? [duplicate]

There is a lot of answer stating that the low enthalpy of atomisation in Cr is due to the reason of partially filled d orbital, thus having extra stability. This makes the orbital more attracted ...
Satyadarshi's user avatar
-2 votes
3 answers
135 views

Why is there a non-uniformity in even the reasons that explain exceptions in the trends in chemistry? [closed]

I have been studying the periodic table and several properties of atoms like the Ionization Energy, Atomic Radii, Electron gain enthalpy, Electronegativity etc. Now, each property has somewhat of a &...
Bhavya Jain's user avatar
-3 votes
1 answer
84 views

Why are p orbitals most important for stability? [closed]

Is there nice way to see/show/derive why p orbitals are so important for stability? Or asked differently: Why are elements with filled p orbitals on the right side of the periodic table? Why aren't ...
user3700272's user avatar
5 votes
2 answers
123 views

What words can I use to differentiate between cases where two atoms are of the same element versus when two atoms are of different elements?

I am writing my thesis, and usually I'm quite good with picking the right words for specific phenomena, yet I am having trouble finding the right words for this specific circumstance. I am trying to ...
thelocalsage's user avatar
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2 votes
2 answers
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How did Mendeleev improve on the Newland's table?

I understand that John Newland’s law of octaves was ridiculed by the scientific community as his table failed to work past calcium. I'm trying to understand how Mendeleev’s table improved on this. On ...
Quin Gardiner Bax's user avatar
-5 votes
2 answers
91 views

In mercury the o shell has 18 electrons but we know that second last shell cannot have more than 8 electrons? [closed]

The last shell has 2 electrons and the second last has eighteen electrons. Byt we know that second last shell cannot have more than 8 electrons. Then how is this possible. Please explain in simple ...
Blazing Cuber's user avatar
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0 answers
243 views

Why wavelength of Rubidium flame test(red violet) is more than Lithium(crimson red)

My teacher show this table from my book Here, you can see Red violet wavelength is more than Lithium, which is against order of visible light which increase according to acronym 'VIBGYOR' According ...
Shinnosuke's user avatar
0 votes
2 answers
114 views

Is the periodic table ordered by bonded atoms and does that change the electron configurations and ordering? [closed]

In my book (Mortimer, The Basic Knowledge of Chemistry) the electron structure of the elements is introduced, there the relative energies of the atomic orbitals are shown: 1s < 2s < 2p < 3s &...
Scindus's user avatar
4 votes
1 answer
363 views

Lower melting points of zinc, cadmium and mercury

I am aware of the fact that d-block elements like zinc, cadmium and mercury have lower melting points than other d-block elements. Also I am aware that these three metals have a fully filled d shell. ...
Shashaank's user avatar
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2 answers
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Is "pentel" a real chemistry term?

Allegedly "pentel" is a synonym for "pnictogen," that is, an element of group 15, the nitrogen group. However, I have not been able to find any sources to support the existence of ...
Sam Kauffman's user avatar
4 votes
1 answer
191 views

Why does berkelium have two electronic configurations?

J.D. Lee Concise Inorganic Chemistry, Appendix E: Electronic Structures of the Elements [1, p. 601] provides two electronic configurations for berkelium: $$ \ce{Bk}\quad \begin{cases} [\ce{Rn}]~\...
Aayush Srivastava's user avatar
3 votes
3 answers
795 views

Why are there so many metals in the periodic table?

Brief Background: I was studying about the 'classical electronic configuration' of the first 20 elements of the periodic table today and was bewildered by the fact that there are an equal number of ...
Chinmay Krishna's user avatar
0 votes
2 answers
420 views

Why ionization energy of Thallium is higher than that of Indium?

I just normally calculated the effective nuclear charge (Zeff) for thallium and Indium from Slater's law, and I found it same for both! That is 5.(If you want calculation for answering or correcting ...
Shinchan Nohara's user avatar
-3 votes
1 answer
113 views

Confusion regarding 1st and 2nd electron gain enthalpy

$\ce{O}$ has the 1st electron gain enthalpy $\pu{-141 kJ mol-1}$. $-ve$ value implies that energy is released when electron is added to an isolated atom. This also means that if $\pu{141 kJ}$ energy ...
Eisenstein's user avatar
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1 answer
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If sulfur is directly below oxygen on the periodic table, why isn't SO the most common sulfur oxide? Instead of third, behind SO2 and SO3? [closed]

Chalcogen like oxygen and sulfur want to 'grab' (or share) two electrons to get to eight, if possible, or maybe 'give up' (or share) six, if necessary, to again get to eight... Right? So, why is ...
Kurt Hikes's user avatar
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2 votes
2 answers
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Why is scandium not in Group 13 despite being once called "eka-boron"?

When drawing up the Periodic Table, Mendeleyev famously predicted the existence of then-unknown elements such as "eka-boron", which we now know as scandium. However, in the modern Periodic ...
dotmashrc's user avatar
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2 answers
557 views

In school, I learnt that Potassium is the most reactive element in the reactivity series. I thought it was Francium?

In school, I learnt that Potassium is the most reactive element in the reactivity series. In the periodic table, the further you go down the more reactive the elemnt is. If this is true, then shouldn'...
Areehant Gupta's user avatar
4 votes
1 answer
370 views

Melting and boiling point of transition-metals, primarily for the groups of Cr and Mn [duplicate]

The NCERT Chemistry book for Grade 12 writes The high melting points of these metals are attributed to the involvement of greater number of electrons from $(n-1)d$ in addition to the ns electrons in ...
Ansh's user avatar
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Just how accurate is this XKCD comic about building a real-life periodic table with cubes made up of each element?

I was reading the book “What If?” by Randall Munroe and this part was very intriguing to me. He answered the question in the title and I was curious if his answer was realistic, and if not, which ...
user177107's user avatar
-4 votes
1 answer
73 views

Doubt regarding trends in modern periodic table [closed]

We know that atomic radius decreases along a period and increases along a group. (Same goes for metallic character) But if we take 2 elements A & B(A is at somewhere in the top and left in ...
Nipun Kulshreshtha's user avatar
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0 answers
163 views

Lead vs Carbon Properties

Lead and carbon are part of the same group on the periodic table, so they have the same number of valence electrons. However, their chemical and physical properties are dramatically different. But why ...
user121618's user avatar
2 votes
3 answers
1k views

Why an atom is more stable when only sublevels s and p are full?

Supposedly when explaining electronegativity and stability of an element, they tell you that it is more stable if the last level is full. That works up to the third period, but after transition ...
Curious student's user avatar
4 votes
1 answer
424 views

How do the odd proton-number elements originate?

I have a question about the origin of the odd proton-number elements in the periodic table, please. As it is generally thought that the big bang produces hydrogen first, and then hydrogen combined to ...
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6 votes
1 answer
267 views

Is there a canonical variable for period and group?

For example, "Z" is the standard symbol for atomic number. I'm writing a manuscript that uses the group and period of elements within some equations, and so far I'm just denoting them as $G_{...
AmphotericLewisAcid's user avatar
-2 votes
1 answer
44 views

Why does $\mathrm{NO_3}$ have charge $1-$? [closed]

I'm given the following problem: Write the molecular equation for the reaction $\mathrm{Iron\;(III)\; Nitrate\; and\; Sodium \;Phosphate}$ I begin by attempting to determine the empirical formula of ...
10GeV's user avatar
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-2 votes
1 answer
216 views

calculation of relative atomic masses in the periodic system [closed]

If I now want to calculate the relative mass of c-13 based on the definition m(c-12) = 12amu, I need the q/m values of c-12 & c-13, where do I find these (I've looked everywhere on the internet)? ...
iwab's user avatar
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1 answer
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Does fluorine have 5 or 7 active valence electrons?

In a paper on chemical periodicities of elements, Cao et al. show the number of valence electrons in a periodic table (https://doi.org/10.1515/pac-2019-0901). Apart from Boron and Aluminum shown as ...
Karsten's user avatar
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How to know the number of valence electrons of f-block elements? [closed]

I kinda know how to get the valence electrons for s/p/d- blocks but i don't know about the f-block. Wikipedia says that valence electrons for f-block is ns + (n-1)d + (n-2)f, so is it true? If so can ...
Elie Makdissi's user avatar
1 vote
1 answer
612 views

How to know the group number from the ionization energy?

The successive ionization energy of the first four electrons of a representative element are $\pu{738.1 kJ/mol}$, $\pu{1450 kJ/mol}$, $\pu{7730 kJ/mol}$ and $\pu{10500 kJ/mol}$. Characterize the ...
An Alien's user avatar
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-4 votes
1 answer
289 views

atomic structure - why only hydrogen be separately written in periodic table [duplicate]

The other exception is hydrogen. It has only one s-electron and hence can be placed in group 1 (alkali metals). It can also gain an electron to achieve a noble gas arrangement and hence it can behave ...
shugo's user avatar
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8 votes
1 answer
546 views

Naming of the chemical elements and original sentences by the discoverers

Does anyone recall a printed or an online compilation where the names of all the chemical elements are listed along with the original sentence, from a research paper, containing the name of the ...
AChem's user avatar
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0 votes
3 answers
119 views

Do Ions with less stability have less energy of ionization than those who are stable?

Problem. I've come up with the strange example of the third energy of ionization of both $\pu{Mg}$ and $\pu{Al}$, the standard logic that is to be applied on any problem of "which element has ...
Acyex's user avatar
  • 135
5 votes
1 answer
863 views

What would happen if electrons were spin-1?

We were speaking about this in class, but I can't understand it quite well. What would happen if (hypothetically of course) the allowed $m_s$ values were $-1$, $0$ and $1$? What impact does this have ...
DIana's user avatar
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-3 votes
1 answer
89 views

Doubts regarding Mole concept and Avogadros number [closed]

So I am really confused about simple topics like mole and Avogadro Here is my oversimplified view So mass of 1 atom of elements in grams was not in whole numbers and it was difficult using em for ...
doesnt exist's user avatar
0 votes
0 answers
77 views

Why is effective nuclear charge used to explain the periodicity of size of atoms and ions?

Why is effective nuclear charge used for explaining the periodicity of size of atoms and ions, even though radius depends upon many other factors? The size of $\ce{Na+}$ is smaller than that of $\ce{...
Osmium's user avatar
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0 answers
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Does the Atomic Mass listed for each element on the periodic table reflect the relative abundances of their isotopes on Earth? Or in the Universe? [duplicate]

Somehow, I cannot find a site or book or paper explaining exactly how the average atomic masses for the elements on the periodic table are weighted.... I posted a question either here or on Physics S....
Kurt Hikes's user avatar
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0 votes
0 answers
128 views

Relation between Ionization energy and reactivity

So I was learning about the periodic table where I came across the topic of ionization energy. As a general trend the Ionization energy decreases as we move down a group with a few exceptions such as ...
Nahul Alaguraj's user avatar
1 vote
1 answer
707 views

What is the name for the relationship between two elements in the same group?

I'm looking for a specific term which can be used to describe two elements in the same group of the Periodic Table. This would be useful since elements in the same group tend to have similar chemical/...
creillyucla's user avatar
7 votes
1 answer
1k views

Spontaneity and nature of attack of fluorine gas on aluminum

What is the nature of the reaction of attack of fluorine gas on aluminium metal? Is it spontaneous in nature? I have studied reactions of halogens on aluminium, but it had no information about ...
Jay's user avatar
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0 answers
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Color of Flame Test for Alkali Metals

Lithium is known to have the highest ionization energy among Group 1 elements. Also, characteristic colours in the flame test arise due to the excitation and de-excitation of electrons. Then why ...
Chaitanya Garg's user avatar
7 votes
4 answers
1k views

Why are there only 7 periods in the periodic table? [duplicate]

Is seven a hard theoretical limit (there can’t be an eighth period) or is it there just because we haven’t discovered/synthesized anything beyond that?
Happy Red Maple Leaf's user avatar
2 votes
2 answers
1k views

How do we know the natural abundance of isotopes on Earth?

Without knowing the Average Atomic Mass or the percent abundance, how do we know that Protium is the most prevalent hydrogen isotope? What methods did scientists use to come to this conclusion? How ...
Gianna's user avatar
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-2 votes
1 answer
65 views

Predict the valence configuration of this element using the first five ionization energies [closed]

If the first five ionization energies of an element are, respectively: $\pu{1.09 kJ/mol}$, $\pu{2.35 kJ/mol}$, $\pu{4.62 kJ/mol}$, $\pu{6.22 kJ/mol}$ and $\pu{37.83 kJ/mol}$, to which group of the ...
Delena's user avatar
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1 vote
1 answer
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Why is Cu(II) more stable than Cu(I)? [duplicate]

Seeing Copper has an exceptional electron filling in its valence shell(4s1 3d10), the way I see it is that on +1, a d10 configuration should be more stable and hence easier to attain than a d9 which ...
Saumya Chaturvedi's user avatar
2 votes
1 answer
985 views

Why does the ionization enthalpy of elements across a period not follow a regular pattern while the atomic size always decreases?

First of all, I would like to mention that I am only talking about elements that aren't from the d or f blocks. In order to further elaborate on my question, I would like to take the third period as ...
Jithendra Kasibhatla's user avatar
1 vote
2 answers
248 views

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 ...
pasaba por aqui's user avatar
6 votes
1 answer
157 views

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 ...
gen-ℤ ready to perish's user avatar
1 vote
1 answer
102 views

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 "...
user17584's user avatar
2 votes
1 answer
56 views

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 ...
Param Budhadev's user avatar

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