Questions tagged [elements]

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Does emission-spectrum of molecule equal sum of emission-spectrum of its components

Imagine a number of elements with known emission-spectra, that form a primary chemical bond of either * ionic * covalent * metallic type. Does the emission-spectrum of the resulting molecule match the ...
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Why does formation of iron in stars doesnt produce any energy?

Why does the formation of iron in the stars doesnt produce any energy, i have a hunch that it might have something to do with the fact that iron has the highest binding energy per nucleon and hence (...
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Finding stable superheavy elements

Finding new stable superheavy elements is big interests in nuclear physics. Nuclides with $Z>92$ are not found in nature, but can be made artificially. Usually these nuclides become more unstable ...
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Why are helium and lithium so different, while lithium and beryllium are similar?

How is it possible that helium, having 2 protons, and lithium, having 3 protons, are so different in terms of their physical properties? How come one is a gas at room temperature and the other is a ...
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Are there names for Helium (He) emission lines like the Lyman/Balmer/Paschen series in Hydrogen?

Just wondering if helium emission lines have names like hydrogen lines. For instance the Balmer series is: $$H_{\alpha}, H_{\beta}, H_{\gamma}, H_{\delta}...$$ The Lyman series is: $$L_{\alpha}, ...
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Why do the elements Tc and Pm have such low abundances?

What specific nuclear and electronic properties make these two elements (Tc & Pm) almost disappear from solar and galactic abundance tables?
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What units are represented by pr - micrometer?

In studying column abundances, I often encounter the units $pr-\mu m$. What does this stand for? Part per micrometer? how can this be an abundance unit? Incredibility I cannot figure out what it ...
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Isn't it entropy (disorderliness) that every atom in the universe is not of iron Fe?

The concept of mass defect and binding energy Iron has most mass defect and the greatest binding energy. It has the most stable nuclei. Nuclei with higher atomic number than iron undergo fission ...
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Facts about element 173 [closed]

I am watching a video about element 173 being the biggest and last element that can ever be assembled. The reason given as the last element that can be created is that the electrons would have to ...
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Bare Critical Masses of $^{241}$Am, $^{242m}$Am, $^{238}$Pu and $^{242}$Pu

$^{238}$Pu has 144 neutrons, and it has 2.8$\times$10$^{3}$ g$^{-1}$.s$^{-1}$ spontaneous fission neutrons and bare critical mass in 10 kg. $^{242}$Pu has 148 neutrons, and it has 1.7$\times$10$^{3}$ ...
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1answer
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Was Helium hydride really the first molecule?

This press release by NASA: https://www.nasa.gov/feature/the-universe-s-first-type-of-molecule-is-found-at-last/ When the universe was still very young, only a few kinds of atoms existed. ...
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Why, precisely, do three elements in a row (iron, cobalt, nickel) show ferromagnetism, but not the elements below them on the table?

The same is true for Neodymium, Promethium and Samarium, right? But like the first three, they are consecutive, not above and below each other. Somehow only elements in those two ferromagnetic 'hot-...
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Element creation in space

In my astronomy magazine I recently saw the periodic system revisited where the elememnts were color-coded according to their production site. For example, Hydrogen was created from the early Universe ...
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Why, precisely, is argon used in neutrino experiments?

Why is argon used in neutrino detectors? Other than liquid argon being denser than water or oil, what are its advantages?
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Why are man made substances in the periodic table?

Why are man made substances such as Berkelium and Lawrencium in the periodic table if they aren't natural substances? I thought the periodic table was suppose to have elements on it, which are the ...
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How many known nuclides are there?

What is the current estimate for the number of nuclides? This is a very basic question, but I'm finding it remarkably hard to get a reliable, up-to-date answer. A few books published in the last 2-3 ...
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Elements Of the periodic table [duplicate]

Why even-numbered elements, with their even proton numbers are more abundant than odd-numbered elements ?
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Why do fusion and fission both release energy?

I only have high school physics knowledge, but here is my understanding: Fusion: 2 atoms come together to form a new atom. This process releases the energy keeping them apart, and is very energetic. ...
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Why does Magnesium burn hotter than other Group 2 elements?

It seems apparent, when one performs the standard "flame tests" in a lab, for the Group II elements that Magnesium burns by far the hottest and brightest. Why is this true? I wouldn't expect this at ...
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How quickly is momentum transferred through an object? [duplicate]

If there was a pole, that was a light year long, out in space. (Away from all physical interference.) If we pushed one end of it, would the other end move instantly? And does it's speed depend on ...
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Why is argon a noble gas but not, say, beryllium or palladium?

Why is argon a noble gas given that the 3d subshell is still empty? More generally, why is it that the filling of a p sub-shell makes an element noble rather than s, d, or f sub-shells, or completed n-...
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How are the relative abundances of isotopes of elements on Earth estimated?

"For example, of all the hydrogen isotopes on Earth, 99.985% occur as an isotope without a neutron and 0.015% as an isotope with 1 neutron. There is a third isotope with 2 neutrons, and is even more ...
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Are any two elements indistinguishable using a single measure? [closed]

According to infoplease.com, elements can be investigated using a range of different techniques to determine their fundamental properties. I'm assuming this list isn't exhaustive. Some properties ...
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What would the periodic table look like in 2 spatial dimensions? [closed]

I looked at this question https://worldbuilding.stackexchange.com/q/13094/, and I think it answers part of my question about how atomic physics would work, but I'm not sure. How many orbitals would ...
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Where do large deposits of heavy elements come from?

I understand that the heavier elements were produced by a series of fusion reactions in a series of stars. What I've never understood is why the atoms of these elements would ever coalesce together ...
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Can any element be a metal?

I was reading that hydrogen can become a metal in some cases, like in Jupiter, and the same for helium. Is this true for all non-metals?
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Commercially available material with highest density to cost ratio? [closed]

What are the top 5 commercially available materials (not limited to just the elements) with the highest density to cost ratio? To point to an application, say that my goal was to mass produce a solid ...
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Is there a database of emission spectra of wavenumber and intensity for all elements?

Is there a database of emission spectra of wavenumber and intensity for all elements? I have been trying to get the emission spectra of all elements from the Atomic Spectra Database but from what I ...
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1answer
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Why are powdered silver and powdered platinum black?

The quantum-mechanical (relativistic) explanations for the observed colours of copper, silver & gold don't appear to explain the black colours of powdered silver (& powdered platinum). Can ...
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What are all the wavelengths of the dueterium spectra?

What are all the wavelengths in the spectrum of deuterium? I've searched and came up with an abstract that only lists the visible part of deuterium's spectrum (see http://myslu.stlawu.edu/~jmil/...
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When will hydrogen no longer be the most abundant nucleus?

In a recent question, we learned why hydrogen is currently the most abundant nucleon or element in the universe. Here I ask a follow-up: For how long will hydrogen be the most abundant nucleus? It ...
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3answers
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Why is hydrogen the most abundant element in the Universe?

Hydrogen is the most abundant element in nature. Does cosmological nucleosynthesis provide an explanation for why is this the case? Is the explanation quantitatively precise?
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1answer
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When you see the atomic mass number for an element, does it take into account the atomic mass defect?

Sometimes I read that the official atomic mass number for an element on the periodic table only includes natural isotope ratios, other times I read that atomic mass defect, number of electrons, etc. ...
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Are there processes other than fusion which can create very heavy elements? [closed]

Have there been hypothesized processes other than nuclear fusion which could possibly create heavy elements? For example these incredibly powerful particle accelerators we are continuously building ...
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If iron can’t undergo fusion, does that mean a black hole is mostly iron?

Since stellar fusion can’t progress beyond iron, and a large enough star collapsed into a black hole because an iron core stalled fusion, wouldn’t that mean all black holes are predominantly iron?
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What is the source for Osmium's colour?

The majority of metals are known for appearing grey to our eyes, cf. e.g. Why are most metals gray/silver? But the main exceptions to this are the "famous" group eleven metals, where their distinctive ...
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1answer
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How can I determine which element is found from an electron count vs binding energy graph

I am given tables of data that I have made into graphs with electron count vs binding energy. The goal of this assignment is to determine the element of the surface material using data that was ...
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Which experimental procedures exist for determining the elemental composition of a nanostructure?

I am doing nanostructures on semiconductors with focused-ion beam lithography, and I am interested to know if the elemental composition is changed at the surface where the sputtering occurred. ...
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1answer
276 views

Reason for exponentially(?) decreasing atomic radius

Attached is a graph depicting atomic radius size across the first 20 elements. Why does the radius decrease in size when going from left to right across a period, and why is the decrease exponential, ...
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1answer
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Why is Helium 4 so stable?

I've been looking at stuff to do with binding energies and was wondering why Helium 4 is so stable. The fact everything up to carbon is less stable seems a bit odd. Is there a reason for this or ...
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Burning atomic elements

when someone says "the carbon was completely burnt up" eg. in a car's engine. what does that mean?, Where does it go? I know no new elements are formed and of course it really didn't disappeared. so ...
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Why do different elements have different number of isotopes?

For example: Carbon-12,Carbon-13 and Carbon-14 are three isotopes of the element carbon with mass numbers 12, 13 and 14 respectively. Lithium-6 and Lithium-7 for lithium,etc. My question is that are ...
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Why are atoms so different from one an another? [duplicate]

An atom is composed of a positively charge nucleus, with a cloud of electron(s) around it. But I can seem to understand the huge differences between 2 components that seem so close in terms of what ...
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The Planetary Light Curve

I know that light can be affected by gravity. But what if there was a planet where if you shone a light in a direction and it could hit your back. I'm talking about a planet where light is bent around ...
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Orbitals and configurations with degenerated energy

When we have to choose, given $n$, $\ell$, where to put an electron, when there are several $m$ orbitals, with the same energy, is there a concrete quantum mechanic rule or some superselection rule to ...
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1answer
102 views

First method to observe solar prominences without an eclipse

What was the first method used to observe solar prominences without an eclipse? I understand that Helium was first discovered in the Sun, separately by Pierre Janssen and Norman Lockyer, in 1868, ...
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1answer
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How well can we calculate atomic spectra from first principles?

Calculating atomic spectra means to me that one takes a Hamiltonian neglecting some effects known to be present (any such Hamiltonian will always neglect something, be it relativistic effects or even ...
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210 views

Grounds state of carbon - Hunds Rule

I have a question about Hund's second rule for the ground state of carbon. Why is it that when S=1, L has to be 1 instead of 2? I don't get the whole symmetric/ antisymmetric argument. Why is L=2 ...
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Missing elements? Electron shell filling after argon [duplicate]

https://en.wikipedia.org/wiki/Electron_configurations_of_the_elements_(data_page) I am confused about shell fulfillment after argon. Argon is 2, 8, 8 1s2 2s2 2p6 3s2 3p6 why is their not ...
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Nickel, Iron and Cobalt attraction strength to a magnet

I cannot find any list of para-, ferromagnetic materials by attraction strength. Particularly, I would like to know which of these (not magnetized) metals is attracted stronger to the magnet?