The periodic table is a systematic arrangement of the known chemical elements in order of atomic number. The elements are arranged in groups on the basis of similarity in chemical and physical properties.

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What exactly is Indium's ability to stabilize non-ferrous metals?

I was reading the History section about Indium on Wikipedia when I came across the following sentence: In 1924, indium was found to have a valued ability to stabilize non-ferrous metals, which ...
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46 views

Name for carbon and boron groups?

So group 17, 16, and 15, are called the halogens, chalcogens, and pnictogens respectively. Is there a name for the groups 14 and 13? (I really don't know if this is on topic here if it isn't tell me ...
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32 views

Why does the second electron affinity has an opposite sign of the first one?

Most of the first electron affinities are positive, therefore the second ones are negative, and vice versa. but why? SPECIALLY WHEN THE FIRST ELECTRON AFFINITY IS NEGATIVE .. WHY THE SECOND ONE IS ...
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How adding one more electron increases the ionization energy?

elements of group 6A, compared to 5A, requires less ionization energy due to the paired electrons of 6A but a question arises... why group 7A,compared to group 6A, requires more ionization energy in ...
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21 views

degeneracy and Mendeleev table [closed]

A very basic question. When we construct Mendeleev table we can think of adding one electron at a time, filling one by one the electronic states, that are numbered by well known quantum numbers (using ...
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22 views

Why does the electron affinity increase in the 15th group

Why does the electron affinity increase by going down through the 15th group?
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1answer
35 views

Trying to figure out what these elements have in common [closed]

I have an old periodic table and I marked five metals from groups 1A and 2A with dots to indicate something about them. Only all this time later I can't figure out what exactly it was. I've been ...
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1answer
34 views

Why does the “gap” between atomic radii get smaller down the periodic table?

The question asks: why is the difference in atomic radii between $\ce{K}$ and $\ce{Na}$ larger than the difference in atomic radii between $\ce{Cs}$ and $\ce{Rb}$? I do have some kind of notion that ...
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34 views

Determine which is more electronegative based on ionization energy

One of the questions I got wrong in my assignment is this one: X, Y and Z are three unknown elements whose first 5 ionization energies are given above. The question is which of the 3 is the most ...
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41 views

Reaction between elements in a periodic table [closed]

Can we know the reaction between any two elements in the periodic table? If yes then can we know the reaction between any three or more elements in the periodic table?
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1answer
42 views

Why does potassium form peroxides but sodium does not?

As we go down the periodic table, Group 1 alkali metals hold their single outer valence electron more loosely, and so reactivity increases. Below potassium (Na, Li), we can store the metal in oil with ...
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134 views

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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2answers
87 views

Periodic table for printing

I there a Good Version of a printable Periodic table Which is minimalistic and gives necessary information only such as - At. Number Element Name At. weight Shell configuration color coding of ...
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1answer
43 views

Actinides and Lanthanides group

I would like to ask which group do actinide and lanthanide belong? I had a question in my assingment that which group has most number of elements? if they belong to 3rd group then the 3rd group should ...
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1answer
59 views

A question about transition metal ions [closed]

Can a transition metal ion with a charge of 2+ form without valence shell s and p electrons?
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35 views

Why are d-orbitals required/used for hypervalent molecules (where the central atom has expanded its octet) [duplicate]

Period 2 elements like carbon, oxygen and nitrogen cannot expand their octet because they cannot make use of d orbitals in that energy level (they don't exist). However, period 3 elements like sulfur ...
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1answer
33 views

How does absence of nd orbital in Oxygen affect its valency?

The original question was 'Oxygen exhibits Oxidation state -2 to +2 but other elements of grp 16 exhibit only +2,+4,+6. Explain Why'. In the solution given i can't understand meaning of this line 'It ...
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1answer
117 views

Why do screening effect decreases due to d-orbital?

I am currently learning about p-block elements. In that in 13th group from Boron to Aluminium atomic radii increases. From Aluminium to Gallium atomic radii decreases. From Gallium to Indium atomic ...
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1answer
57 views

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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1answer
65 views

What is the usage of orbitals more complex than f orbitals?

Every high school learner, in each corner of the world, faces the lesson History of Atom during his courses, just as I did. We learned about s,p,d and f orbitals, though there were no signs of ...
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656 views

Why is gold unreactive when only one electron in outer shell?

I've been trying to answer my (high school) daughter's questions about the periodic table, and the reactivity series, but we keep hitting gaps in my knowledge. So I showed that the noble gases have a ...
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1answer
41 views

Periodic trends: why is effect of protons greater than electrons?

Why is it that adding protons has a greater effect than electron-electron repulsion on periodic trends like atomic radius and ionization energy (assuming # of shells constant)? It seems that if ...
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1answer
200 views

Why is Osmium the densest known element

Why is Osmium so dense, Even if we have more heavy elements post to it.
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1answer
44 views

Show which group the element with Z=31 belongs

and I understand it belongs to the 13 th group, but my teacher wants to express it as IIIA, so how should I convert it in my mind?
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2answers
32 views

How can we confirm the number of protons in an atom?

The periodic table tells us that there are 6 protons in a carbon atom. Is there a way to verify this first-hand? Or are we just expected to believe it unquestioned?
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1answer
402 views

Electronegativity in Krypton and Xenon?

Why do Krypton and Xenon have high electronegativity? Noble gases are supposed to be "happy" with the amount of electrons they have, because they have 8 valence electrons (thus, most noble gases have ...
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1answer
138 views

Outermost electronic configuration of f block elements

I have a doubt regarding the general outermost electronic configuration of f block elements. Why is it $(n-2)f^{1-14}(n-1)d^{0-1}ns^2$. The only exception i thought to this formula was thorium ...
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1answer
147 views

According to what criteria was the periodic table of elements ordered?

I was wondering why the elements in the periodic table were disposed the way they are. I understand, of course, that they are put in increasing atomic number fashion, but I'd like to know more about ...
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72 views

How was Mendeleev able to develop his table?

I asked my general chem instructor this and he didn't know: Mendeleev was able to group elements and discovered a bunch of them and put them in the correct order in the mid-1800s. What equipment did ...
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563 views

Biological Consequences of Asteroid Mining—Death by Isotope?

It's been documented that NASA hope to capture an asteroid in 2025, and have subsequent aims to mine that asteroid. If if this is successful, we would expect other asteroids to be mined in the future. ...
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2answers
87 views

Does there exist any relation between metallic property and oxidation potential?

I was having a revision on periodic table I was thinking about different properties I could connect most of I could not connect metallic property and oxidation potential .
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1answer
69 views

Arrange B , Be , Li in order of increasing IE2

IE2 = Second ionization energy the correct arrange of them is like this : Be < B < Li ... But why? Li will have the greatest IE2 because that will involve removing a core electron but what I ...
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89 views

Atomic radii of Sc,Ti and Fe,Co

The atomic radii of Sc is 162pm , Ti is 147pm , Fe is 126pm and that of Co is 125pm. Electronic configuration of Fe is (Ar)3d6 4s2 and that of Co is (Ar) 3d7 4s2. Difference of Z between them is 1 ...
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1answer
111 views

Block on the Periodic Table?

What are the blocks of the periodic table? What is the purpose of naming the elements per block group? What do they signify?
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124 views

Do isotones share any similarities?

A trivial research in atoms and their basic theories led me to this term: "isotones" Nuclides sharing the same number of neutrons but different atomic numbers. A simple request or shall I say, quest: ...
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Why lanthanides and actinides are shown separate from standard periodic table layout?

In standard periodic table layout , all the elements upto 56 are in order i.e are in the same layout table. However, lanthanides and actinides are always shown separately from the layout like in this ...
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181 views

Classifying atoms as metals or nonmetals based on the periodic table [closed]

The electron configuration of the outer shell of four atoms are: $X: 3s^23p^3, Y: 6s^26p^3, Z: 3s^23p^4 T: 6s^26p^4$. I don't know if these atoms are metal or nonmetal. Please classify the four ...
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1answer
386 views

lanthanide contraction

"The Lanthanide Contraction refers to the fact that the 5s and 5p orbitals penetrate the 4f sub-shell so the 4f orbital is not shielded from the increasing nuclear change." First, 5s and 5p are ...
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The formula for finding the percentage of isotopes in an element's atomic weight?

In my class my teacher showed us how to find it, with a method, but he didn't really state the formula. I conjured up a formula from what I observed and it works. Here it is: $$ \frac{i_1x + ...
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0answers
32 views

Why does sulphur exist as $S_8$ molecule? [duplicate]

Sulphur belongs to the same group as Oxygen. Then why Oxygen exists as an $O_2$ molecule while Sulphur exists as $S_8$ molecule? What's the Chemistry behind it?
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1answer
162 views

What is the most rare element in periodic table

What is the most rare element in periodic table? I have a lot of confusion about this.
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1answer
544 views

Why is lanthanum a lanthanide and actinium an actinide?

I do know that the lanthanides start with the element lanthanum, but why? Lanthanum doesn't even have an $f$ orbital, so why isn't it considered a transition metal? It's the same way with actinium, ...
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1answer
404 views

Memorize Transition Metal Electronic Ground State

In the course of my undergraduate studies it has become clearer and clearer that it is quite helpful to know the ground electronic state of transition metals by heart, if only to speed up the process ...
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313 views

What is the joke that is shown in this picture?

There is supposedly a joke shown in this picture relating to periodic trends. Does anyone know what it is? And could they also explain where the elements on the eye exam came from?
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1answer
518 views

What is the group number or name for elements between group 3 and 4 (F-block) on the periodic table?

What is the group number or name for elements between group 3 and 4 (F-block) on the periodic table? I noticed when I look at a periodic table of elements, the elements of the F-block between group 3 ...
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1answer
361 views

Pair of analogous periods on the periodic table

On the periodic table, period 2 and 3, 4 and 5, 6 and 7 and so on have similar blocks, identical length and groups. What are such pairs of analogous periods called?
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1k views

Why does Ruthenium only have one electron in its 5s orbital in the neutral oxidation state?

So recently I have undertaken some research with some organometallic chemistry involved, specifically regarding that of ruthenium-aryl compounds. Trying to understand the chemistry of the central ...
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1answer
390 views

How many p-orbitals are there in each period?

The question is this: How many p-orbitals are there in each period?a. 1b. 3c. 5d. 7e. 14 I take this to mean "how many p-orbitals are there in each period of the periodic table?" Looking at the ...
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1answer
106 views

Chelation and its relation to transition metal ligands

Can someone explain chelation and its relation to monodentate and tridentate ligands? I dont understand what they mean by chelate effect and chelating rings.
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1answer
280 views

Oxidation state of group 2 elements

I have came across the following statement : "the oxidation state $+II$ is stable for the elements of the alkalin earth metals" , the same is true for the elements of the first group , i've looked for ...