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Questions tagged [elements]

A pure chemical substance consisting of a unique type of atom with a distinguished by its atomic mass.

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Is hydrogen bonding generally defined to include only three period two elements?

Traditionally, hydrogen bonding has been defined to only include interactions between a positively polarized hydrogen and three period-two elements: nitrogen, oxygen, and fluorine. Why was this ...
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6 answers
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The last element's atomic number

I was just thinking what can be the last atomic number that can exist within the range of permissible radioactivity limit and considering all other factors in quantum physics and chemical factors.
Devgeet Patel's user avatar
14 votes
1 answer
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What makes carbon special and versatile?

My teacher told me that carbon's tetravalency and high catenation ability makes it special and is the reason why there are millions of compounds of carbon. 1) Silicon is tetravalent too but doesn't ...
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Why don't we see these lanthanide species?

For most lanthanide metals$^{[1]}$, the stable oxidation state is III. The general electronic structure$^{[2]}$ is $$\ce{[Xe] 4f^{0}^{-14} 5s^2 5p^6 5d^{0}^{-1} 6s^2}.$$ Elements that have the d-...
Linear Christmas's user avatar
10 votes
3 answers
47k views

What is the difference between "molecular mass", "average atomic mass" and "molar mass"?

I don't understand the difference between "molecular mass" and "average atomic mass". They seem like the same thing to me. Is it that average atomic mass is just the weighted average of the "weights"/...
kara's user avatar
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19 votes
2 answers
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Is the relative natural abundance of isotopes of an element the same everywhere?

Wherever you find potassium, the isotopes are present in a set percentage that exists the same everywhere in nature, but why is that? Does it have something to do with how the element is produced?
HyperLuminal's user avatar
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12 votes
1 answer
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Phosphorus standard state

Why is white phosphorus considered to be the standard state of phosphorus although it is only metastable? Red phosphorus is thermodynamically more stable than white phosphorus, yet it is not the ...
Rohan Rajpal's user avatar
11 votes
4 answers
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How were the elements discovered before modern technology?

I recently was in need of zinc for an experiment. So I resorted to obtain it from some dry cell. But I wondered if it was pure zinc or was it $\ce{ZnO2}$ or any other compound of $\ce{Zn}$. It then ...
karthikeyan's user avatar
9 votes
1 answer
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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?
eric's user avatar
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4 answers
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Why are potassium organic salts ever preferable to the sodium equivalents?

$\ce{KOH}$, $\ce{KCN}$, $\ce{KNO3}$, $\ce{K2CO3}$, and plenty of other potassium salts are frequently used in industry. But, as far as I can see, the sodium equivalents are also widely used, often ...
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7 votes
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Miscibility of Molten Metals

While reading about the size of atoms and ions of the Group 1 elements in the textbook "Concise Inorganic Chemistry" by JD Lee, I came across this line: The Li+ is much smaller than the other ions. ...
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Predominance of III oxidation state for lanthanides

For most lanthanide metals, the stable oxidation state is III [*]. The general electronic structure is $$\ce{[Xe] 4f^{0}^{-14} 5s^2 5p^6 5d^{0}^{-1} 6s^2}\ \ [**].$$ Elements that have the d-electron ...
Linear Christmas's user avatar
21 votes
4 answers
4k views

If you put two blocks of an element together, why don't they bond?

Say you have two lumps or blocks of an element, like lithium for example, say in the form of two bars. Why, when you bring the two bars together so that they touch each other, do they not instantly ...
Paul's user avatar
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15 votes
1 answer
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Why is osmium the densest known element?

Why is osmium so dense despite there being heavier elements after it in the periodic table?
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13 votes
1 answer
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Which elements can be diatomic?

Which elements can be diatomic and why? Motivation Hydrogen, Nitrogen, Oxygen and the Halogens tend to be thermodynamically stable as a diatomic molecule at room temperature, and are usually ...
Ali Caglayan's user avatar
8 votes
1 answer
178 views

Which allotropes of sulfur exist naturally?

I'm writing a paper on chemistry and I would like to know which allotropes of sulfur exist naturally. I've searched on the Internet but I haven't found anything about natural sulfur allotropes except ...
Tech Expert Wizard's user avatar
6 votes
2 answers
312 views

How do I correctly typeset metastable radionuclide symbols?

Does anyone know if there is an officially sanctioned way to typeset symbols like technetium-99m (99Tcm or 99mTc)? I have seen both, although in more recent publications, I think, the latter ...
Gavin Kirby's user avatar
21 votes
7 answers
34k views

What is the difference between an element and an atom?

First, I would like to quote sentences from a book introducing elements and atoms: An element is a fundamental (pure) form of matter that cannot be broken down to a simpler form. Elements are made up ...
Jeffery's user avatar
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17 votes
1 answer
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What is the melting point of diamond?

Textbooks and the online reference differ about this and there are more than two answers.
user3286264's user avatar
16 votes
1 answer
772 views

How did Mendeleev know elements from compounds or mixtures?

I read that Mendeleev initially thought didymium was an element, but it was actually a mixture. How did he know the rest of the chemicals in the periodic table were elements and not compounds, ...
Paddyseo's user avatar
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1 answer
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Why is a temporary name given to an element with an atomic number above 100?

All the elements with an atomic number more than 100 are given temporary names by IUPAC according to nomenclature rules. For example, element 101 was temporarily named "Unnilunium" until they give it ...
Freddy's user avatar
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14 votes
8 answers
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Are there any good examples of commonly ingested molecules that contain particular toxic individual elements?

In the house on my own and an article popped up on my feed with the following statement: While the Government has insisted the chemical is safe, cadmium is recognised as a cause of lung cancer ...
Toni Leigh's user avatar
11 votes
2 answers
405 views

Do chemical bonds impact half-life of elements?

Let’s say we have element X with half life of 100 years. Can chemical bonds like X−X or X−Cl increase/decrease half-life of X? As a follow up question, can it increase/decrease radioactivity of X?
suyashsingh234's user avatar
10 votes
4 answers
19k 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 ...
Ordinary Owl's user avatar
5 votes
4 answers
2k views

Phase diagram for first 10 elements

I've been looking on the net for a reference which shows a phase diagram for elements at least from $\ce{H}$ up to $\ce{Ne}$. Specifically, I'm looking which of these elements can be solid or liquid ...
lurscher's user avatar
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1 answer
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Why aren't Boron and Aluminium assigned to group 3 of periodic table? What determines the group? [closed]

I've been curious about this 3D representation of the periodic table "Mendeleev's Flower" and was trying to study it, wondering if it reveals any regularities that are not obvious from classic ...
Andrey Mikhaylov - lolmaus's user avatar
4 votes
1 answer
281 views

Why don't decomposition reactions form pure elements as products?

For example, if I had a reaction like this: $$ \ce{NaHCO3 -> Na2CO3 + H2O + CO2} $$ Why does it not break down all the way down to its elements? What makes it form such "intermediate" products, ...
didgocks's user avatar
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4 votes
4 answers
430 views

Except pure alloys, are there any compounds with more metal elements proportion of atoms than nonmetal elements in proportion of atoms? [closed]

Except pure alloys, are there any compounds with more metal elements in proportion of atoms than nonmetal elements in proportion of atoms? For example, Aluminium oxide has 2 metal elements & 3 ...
user2986288's user avatar
3 votes
2 answers
131 views

Atomic weight = expected weight?

The atomic weight of an element, is it accurate to say that another way to think of it is the expected value of that element's weight if we were to sample one at random from the environment? Are man-...
AJJ's user avatar
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2 votes
0 answers
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Why there is an exception in melting and boiling point in p block?

Why is the boiling point and melting point of 15th group and 16th group has an exception? We know that as molecular mass increases boiling point and melting point also increase. So, down the group 15 ...
Murtuza Vadharia's user avatar
2 votes
1 answer
6k 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?
Scribblenautical's user avatar
49 votes
4 answers
61k views

Why do the names of most chemical elements end with -um or -ium?

Why do the names of most chemical elements end with -um or -ium for both primordial and synthetic elements?
lambda23's user avatar
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39 votes
6 answers
69k views

Why do we use helium in balloons?

While I was looking at the periodic table today, I realised that there were gases that were much lighter than helium such as hydrogen. If hydrogen is lighter than helium, why do we insist on using ...
Ayush Madan's user avatar
34 votes
1 answer
19k views

Melting and boiling point trend in Group II

The following picture shows the melting and boiling point trends down group II elements. I have added question marks where the variability in data was rather disturbing (over two hundred degrees ...
Linear Christmas's user avatar
27 votes
1 answer
11k views

Why do people often capitalize element names?

According to IUPAC rules, names of chemical elements should not be capitalized. See Wikipedia’s take on the issue: According to IUPAC, chemical elements are not proper nouns in English; ...
F'x's user avatar
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23 votes
3 answers
4k views

Why is gold so popular in nanotechnology?

Gold is a very popular metal in nanotechnology. It is often used as a substrate in electronic applications, as a core of functionalized nanoparticles, and more. Why is gold so attractive? Why are ...
Sparkler's user avatar
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19 votes
4 answers
5k views

Will adding up protons and electrons (without neutrons) create a new element?

If protons have a positive charge and electrons have a negative charge, can we add up several protons and electrons together to create a new element, without adding neutrons to hold the nuclei ...
soundslikefiziks's user avatar
15 votes
1 answer
7k views

Why do some element symbols contain a single letter while others contain two letters?

As the title says, why do some element symbols contain a single letter while others contain two letters?
Endy Sun's user avatar
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14 votes
5 answers
5k views

Is there a way to contain fluorine gas for long term so that it can be visually observed?

Bromine, chlorine and iodine can all be sealed in a glass container for display without the elements reacting with the glass. But if you try to seal fluorine in glass I believe it will react and fog ...
docscience's user avatar
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14 votes
1 answer
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Why is Astatine monoatomic?

I learnt that halogens always form covalent bonds to becoms diatomic molecules. So why is astatine monoatomic? I mean they have the same properties, why shouldn't they all be diatomic?
Simon-Nail-It's user avatar
12 votes
1 answer
1k views

Confusion over boiling point of gallium

I am completing a project on gallium, and I need to include its boiling point. I thought that this would be fairly simple to look up, however, it appears that different sources quote different ...
David's user avatar
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12 votes
1 answer
7k views

Reasons for low melting point of gallium

J.D. Lee writes in Concise Inorganic Chemistry: Gallium has an unusual structure. Each atom has one closest neighbor at a distance of 2.43 Å. This remarkable structure tends towards discrete diatomic ...
William R. Ebenezer's user avatar
12 votes
2 answers
14k views

Two different electronic configurations for cerium

Depending on the textbook there are two different electronic configurations stated for cerium. On the one hand $$[\ce{Xe}]\mathrm{4f^15d^16s^2}\quad$$ and on the other hand $$[\ce{Xe}]\mathrm{4f^...
Peter Hofer's user avatar
12 votes
1 answer
2k views

Is it possible that atoms with 120 protons are possible, but that atoms with 119 protons aren't possible?

We currently know that there are atoms with atomic number up to 118 are possible. Is it possible that atoms with 120 protons are possible, but that atoms with 119 protons aren't possible? Or are ...
wythagoras's user avatar
11 votes
1 answer
1k views

What are the most extreme chemicals?

Some chemicals certainly have extraordinary properties. One can consider them extreme in a sense, that they are the prime example for a concept, or they achieve the highest or lowest values in a ...
7 votes
1 answer
16k views

Is it possible for Hydrogen to lose its electron?

I know the basics of Chemistry and one thing I've always wondered if it is possible for Hydrogen to give up it's one electron? I know Hydrogen is eager to share its election through covalent bonds, ...
Dom's user avatar
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7 votes
0 answers
9k views

Which is more electronegative: chlorine or nitrogen? [duplicate]

Why nitrogen is considered to be less electronegative than chlorine. Nitrogen should be more electronegative as I was reading some content about this and I read some reasonable arguments: $\ce{NCl3}$ ...
Hamza's user avatar
  • 308
7 votes
1 answer
9k views

What makes elements radioactive?

I know that certain elements like plutonium and certain isotopes of caesium are radioactive but what gives them this ability? If it's their electron/proton/neutron arrangement, what makes that ...
Okx's user avatar
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6 votes
3 answers
3k views

How was the diatomic nature of many common gaseous elements originally determined?

How did scientists find out that $\ce{Cl2, H2, O2}$ atoms have a two-atomic molecular structure ?
LeDuc's user avatar
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6 votes
1 answer
562 views

Did Berzelius unify the names of chemical elements using the Latin language?

I asked this question because the Chinese Wikipedia community is trying to decide whether it should use Latin names or IUPAC names for the first introductory sentence for its articles on chemical ...
Han-Teng Liao's user avatar