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Questions tagged [periodic-trends]

Trends which are observed in the properties of elements as you move along the periodic table in a given direction.

Trends which are observed in the properties of elements as you move along the periodic table in a given direction. Some of these properties include atomic radius, ionization energy, electron affinity, electronegativity, number of valence electrons, and metallic properties.

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What trends exist in the Periodic Table?

I wish to know the trends in the periodic table and why that trend exists, for the following parameters: Atomic size Ionization energy Metallic character Positive ion size Negative ion size Electronegativity My progress (if my reasoning is wrong…
Tim Xu
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Why is the size of Al3+ less than that of Li+?

Why is it so that the size of $\ce{Al^{3+}}$ is lesser than $\ce{Li+}$? I'm a bit confused about this one as the aluminium(III) ion is composed of 10 electrons and 13 protons, while the lithium ion has only 2 electrons and 3 protons. Electronic…
Kushashwa Ravi Shrimali
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Why does electronegativity increase across a period?

What explains why electronegativity increases as you move across a period? Does it have something to do with the shielding effect of added electrons?
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Will O or S accept an electron more easily?

O has more electronegativity than S but S has more Electron Gain enthalpy than O. How do we decide, which one pulls the electron more easily? In other words, Electron gain enthalpy dominates or electronegativity ?
Aaryan Dewan
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Inert Pair Effect

My notes say that inert pair effect is the tendency of electron in the outermost atomic s orbital to remain unionised or unshared in compounds of post-transition metals. (Eg. Sncl2 is formed preferentially over SnCl4) I've watched a video lecture on…
Kim Mijin
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Available orbitals for promotion

I am under the impression that elements from the third period onwards can promote electrons into d orbitals to form hybridised orbitals. Why would an element in the third period promote an electron to the 3d orbital when we learn that 4s orbitals…
Horatio Cox
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Shielding effect- specifically defined?

In all the sites I have searched, shielding effect has been defined as the reduction of the nuclear attraction upon the outer electron/electrons, due to the core electrons that repulse the outer electron. So, is the shielding effect specifically…
SNB
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Electronegativity trends: Is it more important to prioritize families or periods?

I know that an atom that an atom is more electronegative as it moves up a group or right on a period (in terms of the periodic table). So if you have two atom that is diagonally across from each other, which one is more electronegative? Do you…
Mike
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Why is periodicity seen in these certain properties?

I missed my lesson on periodicity so had to teach myself, and have always forgotten to ask my teacher to explain to me why these trends are seen, which, unfortunately, the textbooks don't. Density: the density of an element tends to increase across…
ODP
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Why is ionization potential considered a periodic property?

Why is ionization potential considered a periodic property??? A periodic property is a one which appears at regular property But we see that every element has some kind of ionization potential
Souhardya Mondal
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Reason of being 2nd ionization energy

Why is the second ionization energy always greater than the first? By shielding effect, it shouldn't have been true. Let's take $\ce{Mg}$ and $\ce{Mg^+}$ for example. Effective nuclear charge(ENC) for $\ce{Mg},Z_{\mathrm{eff}}=Z-$ no. of core…
madness
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Trends in atomic radii across a period

I am a 12th grader. Recently, while revising the Periodic Table, I came across the statement: As the effective nuclear charge increases across a period, the atomic radius of the elements decreases on moving from left to right in a period. For some…
ChaturLomdi
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Why is effective nuclear charge said to be decreased down the group, but the Zeff calculated is increased down the groups instead?

Some textbook write that effective nuclear charge is constant when gping down the group,while some write that the effective nuclear charge decrease down the group So which statement is true? I try to dtermined it by using slater's rule.However,it…
Pck Tsp
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Determining the group number of an element from its successive ionization energies

The successive ionization energies of an unknown element X are: 1st - 9534; 2nd - 11790; 3rd - 13683; 4th - 15309; 5th - 16458. To what group number does X belong? There aren't any significant jumps so that means X is in groups 5-8. After that…
Rishi
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Octet rule violation in Period 2 elements

My textbook states, Period 2 elements typically obey the octet rule. Period 3 and later elements can expand their valence shells. Elements in Periods 5 and 6 of the p-block show variable valence (the inert-pair effect). I was surprised that it…
coder
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