Questions tagged [periodic-trends]
Trends which are observed in the properties of elements as you move along the periodic table in a given direction.
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Teaching Periodic Trends [closed]
I teach physical science, which is an introductory 9th grade physics/chemistry class. Our first chemistry standard is: “Use the periodic table as a model to predict the relative properties of elements ...
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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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Does atomic radius increase down a group due to the shielding effect, the increase in occupied energy levels, or both?
I understand that atomic radius increases down a group (of the periodic table) due to an increase in occupied energy levels, which puts the valence electrons in a higher energy level and further from ...
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3answers
798 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 ...
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Why are hydrated lithium ions' radii larger than hydrated sodium ions' radii?
Why are hydrated lithium ions' radii larger than hydrated sodium ions' radii i.e. $r_\ce{Li+(aq)}>r_\ce{Na+(aq)}$?
If ionic radii increase down the group i.e. $r_\ce{Li+}<r_\ce{Na+}<r_\ce{K+}$...
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Reorganization during ionisation for d block elements
This is a quote from my textbook:
The irregular trend in the first ionisation enthalpy of 3d lmetals,can be accounted for by considering that the removal of one electron alters the relative ...
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3answers
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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 ...
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1answer
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Why does hydration of ions depend on their charge to area ratio?
The following is written in my book Concise Inorganic Chemistry by J. D. Lee.
Hydration energy, hydrated radius and hydration number of a particular ion depends upon the charge per unit area. Hence ...
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1answer
255 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_{...
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2answers
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The oxidation number of N and Cl in NOClO4
My doubt is not about the solution itself, actually I was able to find the solution myself.
We could split NOClO4 as (NO+) + (ClO4-) and then proceed, but here I "knew" this split. Is there ...
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1answer
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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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771 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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1answer
122 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 ...
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3answers
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Which atom is the smallest atom?
Is hydrogen or helium the smallest atom? My teacher said that the smallest atom is the helium atom, but I think that the smallest atom is the hydrogen atom. It has a single electron and a single ...
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1answer
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Why is boiling point of Ammonia greater than Arsine?
I have previously read that the boiling point of Stibane(SbH3) is greater than Ammonia(NH3) as ammonia is gas at room temperature and no hydrogen bonding exists in the gaseous form of NH3.
Hence, as ...
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1answer
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Why is copper a better conductor of electricity than calcium?
How would we compare the electrical conductivity between copper and calcium? I understand that electrical conductivity of a metal is dependent on the number of delocalized electrons for that metal. ...
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The melting and boiling point decreases down the group up to group 14 (not including transition metals), but the trend reverses from group 15. Why?
In groups 1, 2, 13 and 14, the melting and boiling point decreases down the group with a few exceptions. In group 15 the melting/boiling point increases up to Arsenic and then started decreasing. In ...
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What determines the kind of Bravais lattice structure (body-centred cubic, hexagonal, etc) a transition metal shows?
With the exception of Zn, Hg, Cd and Mn transition metals most transition metals have only one kind of lattice structure at room temperature. Another trend I noticed was that Groups 3 and 4 have ...
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Question on d block contraction
For size trend down a group, it is known that:$$Al\gt Ga$$
Due, to d block contraction of gallium.
Why isn't this the case when it comes to silicon and germanium?
Won't the poor shielding effect from ...
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2answers
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Why the radius of noble gases is more than the halogens or the previous groups?
Noble gases have larger radii than that of halogens.
Sometimes it is greater than the radius of group I elements.
Why is it like that? When we talk about radii of noble gases, what type of radius is ...
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4answers
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Why does screening effect decrease due to d-orbital?
In 13th group, atomic radius increases from boron to aluminium. From aluminium to gallium, atomic radii decreases. From gallium to indium, atomic radii increases. And from indium to thallium, atomic ...
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Why does magnesium have a greater ionization energy than lithium?
I'm a high school student and I'm learning about ionization energy and atomic radius of elements. I want to compare the ionization energy of lithium and magnesium.
Here is the information provided in ...
Mathew Mahindaratne
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Is Copernicium a transition metal?
Zinc, cadmium, mercury and copernicium belong to the group 12 of the periodic table. In my textbook , it is mentioned that zinc, cadmium and mercury are d-block elements, but not transition metals. ...
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Why H2S2 is hydrogen disulfide and not hydrogen persulfide?
Context: I was checking this question and in the answer, the compound $\ce{FeS2}$ was named "iron disulphide" (it was previously named "iron persulfide" but later changed after ...
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Exchange energy of d6 configuration
In NCERT Chemistry book, it is given as:
Exchange energy is responsible for the stabilization of energy state. Exchange energy is approximately proportional to the total number of possible pairs of ...
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Regular decrease in the atomic radius of 3d series
While comparing atomic radius, two factors are important:
A. Decrease in size due to increase in effective nuclear charge
B. Increase in size due to increase in shielding effect
I was surprised to ...
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1answer
143 views
Effect of d-orbital electron shielding on atomic radius
In a standard book it is given:
"Atomic radius of Gallium is less than that of Aluminium. This can be understood from the variation in the inner core of the electronic configuration. The ...
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2answers
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Density of d-block elements
Something that confuses me slightly is the trends in density when comparing periods 4, 5, and 6 in the d-block. Looking at periods 5 and 6, the density peaks at group 8, with ruthenium and osmium, ...
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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 ...
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2answers
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Which has the largest bond angle between water, oxygen difluoride and dichlorine oxide?
Which one out of $\ce{H2O}, \ce{Cl2O}, \&\ \ce{F2O}$ will have largest bond angle?
I think it should be $\ce{H2O}$ because oxygen is most electronegative in this case so electrons will be more ...
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How to explain the periodic trends in boiling points in groups?
Observing the trend of boiling points of the compounds listed, choose the appropriate terms to fit into the blanks:
\begin{array}{lr}
\hline
\text{Compound} & \text{b.p.}/\pu{°C}\\
\hline
\ce{H2Te}...
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Why are the melting and boiling points of the group 1 metals lower than the group 2 metals in the same period?
I thought it was because the group 1 metals are smaller than the group 2 metals but the answer sheet says it's because there are more valence electrons and a stronger positive charge in group 2 metals....
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Periodic Trends of Zeff and Electronegativity
The effective nuclear charge $Z_\mathrm{eff}$ increases from left to right and from top to bottom. Can you explain why it increases from top to bottom?
Also can we explain the periodic trend of ...
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1answer
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Why do selenium , tellurium and polonium have more negative electron gain enthalpy than oxygen?
In my book(NCERT Chemistry Part I, Textbook for Class XI[1]) a list of values of electron gain enthalpies of various elements is given. According to that list, oxygen has less negative electron gain ...
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Which oxidation states were used when Pauling developed his electronegativity scale?
Paulings electronegativity is a relative scale, based on the difference in electronegativity between X and Y, $\Delta EN = 0.102 \sqrt {\Delta}$, where $\Delta = (X-Y)_{measured}-(X-Y)_{theoretical}$ ...
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1answer
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Do organopolonium compounds exist?
Analogues of alcohols exist for all the heavier Group 16 elements, namely sulfur, selenium, and tellurium. Would polonium also be able to form a "polonol" like $\ce{CH3PoH}$?
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Why is strontium(II) ion bigger than krypton atom?
$\ce{Sr^2+}$ is exactly the same as $\ce{Kr}$, in terms of electrons and orbitals.
The only difference between the two, is that $\ce{Sr^2+}$ has a couple of extra protons in the nucleus (and probably ...
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Acidic character and anion stability across periods and groups of the periodic table [duplicate]
I understand that to compare relative acidity one must consider the stability of the conjugate bases.
Across a period the electronegativity of an element increases. And that is for example why $\ce{HF}...
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Electron Affinity of Lead as compared to Bismuth
For "nitrogen family" and "carbon family" the trend goes that in a period, the electron affinity in case of group 15 is less than that of group 14. This is attributed to the half-...
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Why do the boiling and melting points decrease as you go down group 1 and vice versa for group 7?
I used to think that because an alkali metal needs to lose one electron to complete its outer shell, when the atom increases in size (atomic radius), the electron would be easier to lose as the ...
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1answer
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Why are group 1 elements so low in density?
I was studying the s-block elements and found that they extremely low in density. Lithium is said to be the least dense solid in the entire periodic table and their Cohesive Energies are also very low....
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S(p)-C(p) vs. O(p)-C(p) overlap
In Grossman, The Art of Writing Reasonable Organic Reaction Mechanisms, he provides the following explanation. The question asks to explain why the difference in pKa values between PhSH and EtSH is ...
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Is there an enolate equivalent for enamines?
I'm learning that enolates are stronger than enamines are stronger than enols in terms of general nucleophilicity. Makes sense. But what I can't find any explanation for online is why the trend ...
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Why is fluorine more reactive than iodine despite the weaker I-I bond?
The atomic radius of halogens increases as we go down the group due to the addition of new shells. As a result, the bond length of halogen $\ce{X-X}$ increases down the group. So, less energy is ...
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Why is the increase in covalent radius from As to Bi not as big as from N to P?
The following is the radius of Group $15$ elements:
$$\begin{array}{c|c} \hline
\text{Element} & \text{Covalent Radius }(\pu{pm}) \\ \hline
\ce{N} &75 \\
\ce{P} &110 \\
\ce{As} &...
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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 ...
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Why is magnesium sulfate more soluble in water than that of strontium and calcium sulfates?
Magnesium sulfate is soluble in water. Its solubility is $\pu{26.9 g}/\pu{100 mL}$ at $\pu{0 ^\circ C}$ $(\pu{35.1 g}/\pu{100 mL}$ at $\pu{20 ^\circ C})$.[1]
However, both calcium sulfate $(\pu{0.21 g}...
Mathew Mahindaratne
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Out of KCl, CaCl2, MgCl2, NaCl, which causes the greatest corrosion rate of iron and why?
I know that salts act as an electrolyte in a redox process and rusting of iron, where iron loses electrons and oxidizes, and oxygen gains electrons and reduces. I did an experiment with KCl, NaCl, ...
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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 ...
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Ionization enthalpy for group 13 elements
The ionization enthalpy for elements along a group generally reduces.
But there is an exception for group 13 elements and the order is not
uniform.
The order is:
B>Tl>Ga>Al>In
According to ...
