All Questions
Tagged with periodic-trends periodic-table
88
questions
4
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1
answer
51
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Why does the 1st ionisation energy decrease from the 9th period to the 10th period
I’m currently looking at the ionisation energy chart within my chemistry textbook and while I know that there are not really meaningful periodic trends within transition metals, generally the ...
- 53
0
votes
0
answers
66
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Upon what does the half life of a nuclide depend on? [duplicate]
Nuclide half-lives seem to be apparently random, except for the fact that heavier elements are typically radioactive and lighter ones stable. Is there any factor that can predict the half life of a ...
- 109
-3
votes
3
answers
534
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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 ...
- 13
0
votes
1
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502
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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 ...
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-2
votes
3
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169
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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 &...
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2
votes
2
answers
298
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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 ...
0
votes
2
answers
117
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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 &...
- 369
4
votes
1
answer
554
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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.
...
- 372
0
votes
2
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863
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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 ...
-3
votes
1
answer
179
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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 ...
- 161
-4
votes
1
answer
81
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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 ...
2
votes
3
answers
2k
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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 ...
6
votes
1
answer
273
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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_{...
2
votes
1
answer
394
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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 ...
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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 ...
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