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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Why doesn't Sodium (Na) form duplet?

The atomic number of Na is 11 (2, 8, 1). Na loses an electron to achieve octet stability but why can't it just accept an electron to complete duplet stability?
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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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How many elements can be in one molecule? [duplicate]

How many elements can be in one molecule? What is the maximum number of chemical elements in one molecule?
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Does the Atomic Mass listed for each element on the periodic table reflect the relative abundances of their isotopes on Earth? Or in the Universe? [duplicate]

Somehow, I cannot find a site or book or paper explaining exactly how the average atomic masses for the elements on the periodic table are weighted.... I posted a question either here or on Physics S....
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what does it mean to say oxygen in a given context?

My textbook "chemistry by Julia" says the following When it comes to expressing the molar mass of elements such as oxygen and hydrogen, we have to be careful to specify what form of the ...
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Trends of electron affinity

Trends for electron affinity going across the group increases negatively. Does this mean Noble gases' electron negativity is more negative than halogens? I'm confuse here. Noble gases should have a ...
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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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4answers
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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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Why isn't hydrogen gas an element according to the definition of an element? [duplicate]

I read the definition of element: Element consists of only one kind of atom and cannot be broken down into a simpler type of matter by either physical or chemical means. Then as per definition, $\...
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Are the names for chemical elements the same in both modern Greek and classical Greek? [closed]

I am curious whether the modern Greek names for chemical elements were adopted from Classical Greek, both Latin and Classical Greek, or some international standard? I'm unsure if this is the correct ...
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What is the color of elemental silver?

From my lab book it says it is black? I don't understand how we know the color of it is black. Can anyone explain?
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1answer
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What does being an “elementary substance” mean?

Which of the following isn't an elementary substance? Ozone Sulfur diamond quartz I don't get what elementary substance means. By seeing the options and the word elementary, I guess it means ...
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Elements other than carbon that can form many different compounds by bonding to themselves?

My textbook says the following: Unique among the elements, carbon can bond to itself to form extremely strong two-dimensional sheets, as it does in graphite, as well as buckyballs and nanotubes. ...
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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 ...
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1answer
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Which atoms form which elements?

Is there a diagram/flow chart available that shows which atoms fused together to make each of the elements? I can find examples for some elements, but nothing which shows all the combinations of ...
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2answers
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Can our chemical elements be differents on other universes? [duplicate]

Let's pretend that in other universe we have an element with atomic number 6, like our carbon, but in this other universe the element is completely different from our carbon, like a new element with ...
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What is the difference between metaphosphoric acid and phosphonic acid? [duplicate]

Are metaphosphoric acid and phosphonic acid the same? I have been told that they're same BUT the structures online are different. Metaphosphoric acid has formula: $\ce{(HPO3)_n}$ phosphonic acid ...
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Where do I find data on 'molecular membership' sequences?

Techniques such as isotopic labeling allow for radioactive tracing of an element through a sequence of molecules. Using analytical instruments (such as LC-MS) we can then find out where labelled atoms ...
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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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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^...
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Why are the rare Earth elements divided into light and heavy categories?

Rare Earth's up to z=62 (Samarium) are often called 'light' rare Earths, while z=63 (Europium) and beyond are sometimes referred to as 'heavy' ones... Why the distinction, though? Never have I come ...
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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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Predict the valence configuration of this element using the first five ionization energies [closed]

If the first five ionization energies of an element are, respectively: $\pu{1.09 kJ/mol}$, $\pu{2.35 kJ/mol}$, $\pu{4.62 kJ/mol}$, $\pu{6.22 kJ/mol}$ and $\pu{37.83 kJ/mol}$, to which group of the ...
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How can chlorine be 'only' the third-most electronegative element yet have the highest electron affinity?

From Wikipedia: It is an extremely reactive element and a strong oxidising agent: among the elements, it has the highest electron affinity and the third-highest electronegativity on the Pauling scale, ...
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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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Does there exist a molecule of formule XαYβ where X and Y are elements that are also found in molecule XγYδ? [closed]

I am not a chemist, but I will be explaining chemistry to some third-graders. I want to give the example of how different things can be made of the same parts, but arranged differently. My "real ...
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How are the boiling points of Tungsten and other metals determined and proved?

The boiling point of Tungsten is 10,030 degrees Fahrenheit. How was this determined and proved? And more generally how are the boiling points of metals determined and proved? Is it really so simple ...
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Oxidation number approximately

I argued with my lecturer when he is saying that during the calculation of oxidation number, and your answer give you like 3.46 you can approximate it to whole number, I know tell him NO that if the ...
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Probability of forming dihydrogen with molecular weight 3 [closed]

During a lecture, my professor told us that the probability $P$ to form a hydrogen molecule $\ce{H2}$ with mass number 3 could be calculated out of the abundances, $\gamma$, of the isotopes of this ...
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Electronegativity (Oxygen and Phosphorus)

What makes an element electronegative. I understand, for example, $\ce{P(OR)3}$ is less basic than $\ce{PR3}$ because the oxygen in $\ce{P(OR)3}$ is more electronegative than P, so it pulls electron ...
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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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Could there ever be a way to safely handle visible amounts of elements like astatine, francium, or protactinium? [closed]

This is something I'd actually be interested in doing if possible. I've asked about artificial stability here https://physics.stackexchange.com/questions/584595/could-there-at-least-theoretically-ever-...
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How would someone in 1917 describe elements 43, 61, 72, 75, 84, 85, 87, 89, and 91? [closed]

https://books.google.com/books?id=aaELAAAAYAAJ&printsec=frontcover#v=onepage&q&f=false Notice the list of elements on pages 62–63. It includes a short description of each element's "...
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Can someone help me figure out what the noble gas configurations for zirconium and holmium are? [closed]

I am currently working on noble gas configurations in chemistry and I am having a hard time understanding why I got two questions wrong on a practice. The instructions for the practice are here: Write ...
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1answer
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What is the reason behind the characteristic colours of elements?

I've been trying to find out about this for some time now and when I searched online, I couldn't get any proper reasons. My question is: What is the reason for the characteristic colours of elements? ...
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Why can't Astatine form a diatomic homonuclear molecule like the rest of the halogens? [duplicate]

My understanding of chemistry is very elementary. I was reading about diatomic molecules and found the following image showing which elements can exist as diatomic (2 atoms) homonuclear (same element) ...
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Is there a standard scholarly reference for lattice constants of crystals of the elements?

I need to discuss the lattice constants of bulk crystals of several metal and semiconductor elements. I can find plenty of tables and numbers that are probably "close enough" but for a paper ...
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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?
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How do you know what elements will bond in a reaction? [closed]

I know all about the types of reactions, synthesis, decomp. etc., but when a bond is broken, how do you know that the free element will bond to another molecule? Is it because that element has a ...
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1answer
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A theoretical chemistry question about elements and their presence over time [closed]

I'm not a chemist myself, but I can't think of a better place to get some insight about elements and chemistry than from people who live and breathe it here on stackexchange. This is not any kind of ...
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1answer
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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, ...
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Chemical elements or compounds with yellowish white color [closed]

Are there chemical elements or compounds that have a yellowish white (cream) color in their natural state?
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How do scientists know they have discovered an element? [duplicate]

I have a background in math not chemistry and perhaps this question is inappropriate but I will try. I read that after pitchblende was discovered Martin Klaproth in 1879 a latter date discovered that ...
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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 ...
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Reactivity and its meaning

When we say that “potassium” is reactive, are we referring to a potassium atom or bulk potassium as in the solid metal? In other words does “potassium” refer to a type of atom or an agglomeration of ...
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Is there any elemental molecule which does not react well with anything but oxygen? [closed]

For example, phosphor reacts with oxygen but it also easily reacts with many halogens, metals, etc. Is there any elemental molecule that doesn't react well with almost anything but oxygen?
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Similarities between Co and Ni [closed]

Elements $\ce{Co}$ and $\ce{Ni}$ share many similar/same properties and usually if one of them is an example of some group (e.g., ferromagnetism, same possible oxidation states, packing fraction and ...
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What element has good conductivity but is also brittle? [closed]

I'm confused by what element(s) can be identified to have these properties. The following is text from my 2019-2020 Kaplan MCAT General Chemistry book under the metalloids section Silicon (Si) has ...
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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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Why do elements have mass numbers? [duplicate]

I don't really understand why an element has a mass number, I thought that an element has several isotopes, each with a different mass. Is my understanding correct: The mass number of an element ...

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