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.

learn more… | top users | synonyms

3
votes
0answers
44 views

Why are there 3 columns in Group VIII of the Periodic Table?

I'm currently reading in-depth about the layout of the Periodic Table, and I wondered why the table has 3 columns in its Group VIII: As I understand, this is an old notation of the table, now ...
1
vote
1answer
23 views

What properties do scientists predict for later elements?

Though scientists have predicted up to element 172 (unseptbium) what properties do they predict any elements later on the extended periodic table may have?
0
votes
0answers
21 views

Is There any way to Easily Remember the Periodic Table [duplicate]

So for a test we have to memorize the periodic table. I was wondering if there was any easy way to remember it. Please Help.
1
vote
1answer
39 views

Why do some periodic tables have 18 groups while others have 8?

In school I have been taught about the periodic table with 8 groups, representing the number of electrons in the outer shell (with exceptions). But online almost all I can find is periodic tables with ...
0
votes
1answer
24 views

2nd Electron Affinity of halogens

I have seen questions regarding EA but they were all about the 1st EA so this question is not duplicate. I came across a statement which goes like "2nd EA of halogens is almost zero". How is this ...
0
votes
1answer
35 views

What is the correct order of chemical reactivity in terms of oxidising property for the following elements: F, Cl, O, and N

This is a textbook question. I am confused as to which factors i should consider while sorting out these elements. If I take electron gain enthalpy, then Cl should be greater than F, but if i consider ...
0
votes
0answers
11 views

Reverse trend in solubilty for alkali metals

In case of alkali metals, why does ENTHALPY OF FORMATION for fluorides become less negative down the group and opposite for chlorides, bromides and iodides ?
4
votes
1answer
70 views

Why can mercury(I) exist, but not zinc(I)?

Mercury shows variable valency while zinc does not. Its electronic configuration is $\ce{[Xe]\:4f^14 5d^10 6s^2}$. So it can donate the $\ce{6s^2}$ electrons and should only be able to form ...
5
votes
1answer
49 views

Deviation of Ytterbium from general trend

What is the reason for deviation of ytterbium from the general trend of lanthanides in terms of hardness, melting point, density etc.?
1
vote
0answers
34 views

Anomalous Electronic Configuration of Thorium

The electronic configuration of thorium ($Z=90$) is $5\mathrm f^0 6\mathrm d^2 7\mathrm s^2$. But, according to the aufbau principle, the electrons should first enter the $\mathrm f$ subshell and not ...
2
votes
5answers
368 views

In the periodic table, why doesn't the 2nd row have exactly 2 elements?

Row 1: 2 elements Row 2: 8 elements Row 3: 8 elements Row 4: 18 elements Row 5: 18 elements Row 6: 32 elements Row 7: 32 elements In other words: 2, 8, 8, 18, 18, 32, 32 Why does the first ...
1
vote
1answer
69 views

Why is the periodic table periodic?

I am not a chemist, but I am interested in Science in a general sense. Can anybody explain why the periodic table is periodic in nature? I would appreciate links for further reading.
0
votes
2answers
65 views

Why is Aluminum's 2nd ionization energy higher than Silicon's?

According to the periodic table trend for I.E. Silicon should have a higher 2nd ionization energy than Aluminum so I'm confused.
0
votes
0answers
19 views

Why is mercury in the copper group?

In various old inorganic chemistry manuals it seems to have been the practice to group mercury in with the "copper group". Why is this?
1
vote
1answer
240 views

How long the block starting with element 121 will be?

I remember from my chemistry classes that (after the initial irregularities) a new block of elements starts every two periods. After the initial s-block and p-block following it shortly, we have ...
3
votes
1answer
210 views

Why does the boiling and melting point 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 ...
1
vote
0answers
34 views

Chemical mixing question [closed]

What happens when Hydrogen is mixed with every chemical individually? What kind of reaction occurs? What happens when Lithium is mixed with every chemical individually? What kind of reaction occurs? ...
-3
votes
1answer
61 views

Why do the chalcogens (Y) form YX4, YX6 but not YH4, YH6? [duplicate]

What is it about hydrogen that makes it different from the halides? What makes it only form di- and not tetra- or hexa- hydrides of the chalcogens?
3
votes
0answers
22 views

What explains the very high density of osmium and iridium? [duplicate]

Iridium with a density of $22.56$ g cm-3 & osmium with $22.59$ g cm-3. Data from their respective Wikipedia pages. Only these two naturally occurring elements have such a high density. I wish to ...
1
vote
1answer
120 views

What are inner core electrons and how do they influence chemical and physical properties?

There are six groups of p–block elements in the periodic table numbering from 13 to 18. Boron, carbon, nitrogen, oxygen, fluorine and helium head the groups. Their valence shell electronic ...
2
votes
0answers
19 views

How do I know the valence number by looking at the groups? [duplicate]

Groups say the valence number. For example Hydrogen is on group 1, has 1 electron on it's last and only level. So we can know the valence number on that are on the groups 1-2 and 13-18. But how am I ...
1
vote
1answer
56 views

A doubt about something related to elements above Feynmanium

Here I saw that if an element above atomic no 137 has to exist, it must have electron speed greater than speed of light. My question is , has this calculation been done keeping in mind Einstein's ...
2
votes
0answers
92 views

How do I model atoms with Moebius strips?

This question came to me while I was trying to model the list of elements (Mendeleïev), especially their masses and number of electrons. It came to my mind that it might be easier to model each ...
2
votes
2answers
2k views

Is iron the most stable element in the periodic table?

According to the binding energy per nucleon vs mass number graph, it is observed that iron-56 has the maximum value of binding energy per nucleon (8.75 MeV).It means that Iron-56 is the most ...
3
votes
1answer
59 views

Periodic table- quantum numbers

I have come across many questions like: "if electron had 3 spins (-1/2,0,+12) then what change will be there in the periodic table?", also sometimes " if the capacity of each orbital becomes 5 then in ...
2
votes
0answers
22 views

Families of some columns [closed]

From previous lessons, I know that column 1 are alkali metals, column 2 are alkaline earth metals, column 3 till column 12 are transition metals, column 17 are halogens and column 18 are inert gases. ...
1
vote
1answer
626 views

Memorizing polyatomic ions? Using Periodic Table

In my Chemistry course, we must memorize a list of common polyatomic ions. Is their an easy way of memorizing ions such as Sulfate $\ce{SO4^2-}$ by looking at just the periodic table. I listed the ...
8
votes
1answer
260 views

Periodic table group naming confusion - schools don't follow latest IUPAC?

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 ...
0
votes
0answers
17 views

Easy method to mug up periodic table? [duplicate]

Is there any way or shortcut to mug up periodic table elements in order. I always mix up the order and forget their atomic numbers, etc. I am now in class 12. So all elements are not required. Only ...
3
votes
0answers
129 views

Why is lutetium part of the lanthanide series?

I’ve been looking at the periodic table and began to wonder - why is lutetium part of the lanthanide series? Or, for that matter, why is lawrencium part of the actinide series? This isn’t readily ...
0
votes
1answer
308 views

Anomalous configuration for Palladium?

The p block elements generally have the general valence she'll configuration as $$n\mathrm{p}^{1-6}\,n\mathrm{s}^{1-2}.$$ Expected electronic configuration for palladium is $$\ce{^46Pd} = ...
4
votes
0answers
114 views

Which element has a greater second electron affinity, sulfur or oxygen?

I found a question asking the above which states that sulfur has a lesser second electron affinity than oxygen. But since the inter-electronic repulsion in sulfur is lesser, shouldn't it be willing to ...
8
votes
1answer
459 views

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 ...
3
votes
1answer
1k views

Trend in the melting point down the group

We know the the atomic radii increase down the group. So less energy is required to pull the outermost electron as we go down the group and gradually melting points decreases down the group. The ...
7
votes
2answers
4k views

Is aluminium a metal or metalloid?

Aluminium is along the dark line of the Periodic Table and it is $p$-block metal. Is it metal or a metalloid? Why?
4
votes
1answer
681 views

Are the elements lanthanum and actinium considered to be in the d block or the f block of the periodic table?

Many periodic tables place lanthanum and actinium in the f-block of elements, for example, this periodic table from Los Alamos National Laboratory. However, this table from the Royal Society of ...
13
votes
1answer
12k views

Why are there peaks in electronegativities in d-block elements?

Looking at the Pauling electronegativities in the Periodic Table (below, from ChemWiki): Asides from the overall trend of increasing electronegativity across and up the Periodic Table (towards ...
0
votes
1answer
118 views

Periodic table groups - which grouping is “right”? [closed]

In searching online, I've noticed there are a lot of different ways to group the elements of the periodic table. Take mercury in the two tables linked below, for example: ...
11
votes
3answers
635 views

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 ...
14
votes
1answer
667 views

Is there a function to approximate atomic mass from the atomic number?

The product of $2Z$ generally approximates the value of $m_\mathrm{a}$ of atoms that comprise relatively few protons. Whereas, the product of $2.5Z$ generally approximates the value of $m_\mathrm{a}$ ...
23
votes
1answer
2k views

How come uranium's relative atomic mass is 238.03 when it only contains isotopes with a mass number of 238 or less?

I have always been led to understand that the mass of an element on the periodic table is the weighted average atomic mass over all naturally occurring isotopes. This seems to make sense with all the ...
2
votes
2answers
79 views

Why isn't helium always He 1s?

Part 1: According to what I've learned so far, helium is in the first row of the periodic table, so its $n$ should always equal $1$. However, a question in my text asks about helium 2s. What is helium ...
3
votes
2answers
988 views

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 ...
2
votes
1answer
141 views

Reading number of outer shell electrons and other properties from periodic table?

How can one read from the periodic table the number of outer shell electrons that an atom has, to predict how these atoms will make bonds with other atoms? For example to see that hydrogen ($\ce{H}$) ...
1
vote
1answer
87 views

What number should go underneath this fictitious element on the periodic table? [closed]

A new element (Wickium) was discovered on Mars. The isotopes of Wickium are Wickium-199, Wickium-200, and Wickium 201. The percent abundance of Wickium's isotopes are as follows: $$\ce{^199Wi} = ...
0
votes
1answer
60 views

Organisation in Periodic table [duplicate]

Why do we find big spaces in the periods of the Periodic Table between $\ce{H}$ and $\ce{He}$, $\ce{Be}$ and $\ce{B}$, and $\ce{Mg}$ and $\ce{Al}$? What is the logic of such organization of the ...
4
votes
1answer
6k views

How to find density of element metals

I was wondering, how do I determine what metal (element) has the highest density by using the periodic table? Is it possible?
0
votes
1answer
53 views

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 ...
3
votes
1answer
103 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 ...
4
votes
1answer
2k 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 ...