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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.

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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Above is the standard periodic table used by most scientists around the world. However, alternatives exist, ranging from useful ones which order the elements based on electron configuration, to artistic designs which are purely aesthetic in their appeal.

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What are the alternatives to the Periodic Table of the Elements?

What are the different diagrams/tables used to organize the elements other than the Periodic Table? What are the advantages/disadvantages of each?
RandomDuck.NET
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To which block of the periodic table does helium belong?

According to quite a few books I have read, helium belongs to the p-block with reasoning along the lines of "it's an inert gas, so let's clump it together with other noble gases which are in the p-block." However, on Wikipedia, helium is classified…
paracetamol
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Is there an abundance threshold of a 'synthetic' element for it to be considered natural?

I always (possible naively) thought that elements are either natural or synthetic, either one or the other. But, according to the Wikipedia page about Synthetic Elements, it states that: All elements with atomic numbers 1 through 98 are naturally…
user15489
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Why are metalloids found in a zig-zag line on the periodic table

I am confused about the zig-zag pattern of metalloids in the periodic table. Why are metalloids arranged in a zig-zag line? Can anyone answer my question?
Eddy Kwong
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Confusion with the Periodic Table

The periodic table has 7 periods and they have 2,8,8,18,18... elements respectively from 1 to 7. But from what I understand, the periods each state the number of electron shells that the elements in that period has. So if that is the case, shouldn't…
phi2k
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Mendeleev's predictions

While studying about Mendeleev's periodic table in my textbook( class 11 NCERT chemistry), I have studied that Mendeleev has predicted some elements like Eka-boron(scandium), Eka-Aluminium(Gallium),Eka-Silicon(Germanium)etc. He also predicted their…
sai saandeep
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Why are there only 7 periods in the periodic table?

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
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Why don't Schools follow latest IUPAC for naming groups?

In high school I am taught that Group 7 were halogens and Group 8 were noble gases, and Group 3 the boron group, Group 4 was carbon group, etc. Then when I looked up the groups, I found that noble gases were group 18, halogens were group 17, Group 7…
Nihilist_Frost
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Where did the rest of the elements come from?

There were ninety original elements on the Periodic Table. Over time, new ones were founded and put on. However, they were all either the original elements experimented on. For example, Plutonium was discovered by deuteron bombardment of uranium.…
user904
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How can scientists be certain that there are no undiscovered elements missing from the periodic table from hydrogen to lawrencium?

Scientists are certain that there are no undiscovered elements missing from the periodic table from hydrogen to lawrencium. How? and why?
user773
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What is a "period" of the periodic table?

I'm familiar with the periodic table / periodic system, but I wonder why it's called "periodic" since there seems not much periodic about (there seems to be little or no predictability of which elements are stable) and from physics I know Z-value of…
Niklas Rosencrantz
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Why are group 1 elements called alkali metals and group 2 elements are called alkaline earth metals?

I was studying the periodic table. My teacher said that Group 1 elements are called alkali metals because their oxides are soluble in water and group 2 elements are called alkaline earth metals as their oxides form in the earth and are water…
MartianCactus
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What do the numerals on the top right corner of the cells in the periodic table represent?

On the table published here (link) each cell has one to five numerals arranged vertically in its top right corner. The sum of those numbers is always the relative atomic mass of the element. I suspect that, in most cases, two of those numerals…
Hal
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How to quickly predict the group of elements with atomic numbers 117 and 120?

The elements Z (atomic number) = 117 and 120 have not yet been discovered. In which group would you place these elements? I tried to write their electronic configurations but it was too tedious and I do not remember the Aufbau principle to that…
GK A
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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 be the answer. Am I wrong or Right? Please Help…
Aditya ultra
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