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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14
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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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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.
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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-...
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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"/...
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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 ...
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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?
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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?
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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 ...
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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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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 ...
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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 ...
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Predominance of III oxidation state for lanthanides [closed]

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 ...
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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 ...
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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 ...
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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 ...
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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-...
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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.
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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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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, ...
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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?
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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; ...
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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 ...
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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 ...
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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 ...
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1answer
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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 ...
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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?
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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?
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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 ...
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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 ...
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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 ?
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Difference between catenation and allotropy

Can anyone tell me what the difference between catenation and allotropy is? I would like the basic explanation.
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At what temperature (in kelvin) are most of the elements on the periodic table liquids?

This question is out of pure curiosity. At what temperature are a majority of the elements on the periodic table in a liquid state/phase of matter? For the purpose of this question, assume the ...
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1answer
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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, ...
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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 ...
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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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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 ...
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Ground state electron configuration of chromium [duplicate]

What is the ground state electron configuration of chromium? Is it $\ce{[Ar]}4s^23d^4$ or Is it $\ce{[Ar]}4s^13d^5$
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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 ...
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1answer
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Does ionization energy have anything to do with how reactive an element is?

According to my textbook, fluorine has a pretty high (compared to elements like sodium) first ionization energy. But why does it have such a high requirement to ionize? After all, it actively seeks ...
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Does mercury have an NFPA 704 classification?

I've searched on a lot of websites if elemental mercury (Hg) has an NFPA classification but I can't find any. Does mercury have an NFPA classification?
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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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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 ...
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1answer
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Chemical Test for tin

How can I distinguish whether a metal that I have is tin ($\ce{Sn}$)? I am specifically looking for a chemical reaction that will happen only with tin and not with other metals such as $\ce{Al,~Cu,~Fe,...
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How to find the empirical formula for an nitrogen oxygen compound from the given mass of nitrogen and the product?

$5.00~\mathrm{g}$ of nitrogen is completely converted into an oxide of nitrogen. The mass of the oxide formed is $19.3~\mathrm{g}$. The empirical formula of the oxide would be? My working: $$\ce{...
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Relativistic effects in element 137 (Feinmanium) and above

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 ...