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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What is the number of 3d electrons of the transition metal ion in the following complex: [closed]

What is the number of 3d electrons of the transition metal ion in the following complex: [Cr(OH2)4Cl2] Im confused how to count the electron config if it is complex. is there a very easy way to ...
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Why does sulphur exist in two forms in solid state, monoclinic and rhombic? Why in one favoured over another at a certain temperature and pressure?

Both Rhombic and Monoclinic sulphur consist of $S_8$ molecules packed together. Yet the former is more stable below $114^{\circ}C$ at 1 atm and spontaneously converts to monoclinic sulphur above that ...
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The melting and boiling point decreases down the group up to group 14 (not including transition metals), but the trend reverses from group 15. Why?

In groups 1, 2, 13 and 14, the melting and boiling point decreases down the group with a few exceptions. In group 15 the melting/boiling point increases up to Arsenic and then started decreasing. In ...
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How many atoms are there in single element? [closed]

Elements are chemical substances made up of the same types of atoms (atoms with the same proton number), whereas molecules are chemical compounds made up of atoms from two or more different elements. ...
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What is the sign of first electron affinity? [duplicate]

I have found contradicting information on this all over the net. From Libretexts When an electron is added to a neutral atom (i.e., first electron affinity) energy is released; thus, the first ...
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Why is effective nuclear charge used to explain the periodicity of size of atoms and ions?

Why is effective nuclear charge used for explaining the periodicity of size of atoms and ions, even though radius depends upon many other factors? The size of $\ce{Na+}$ is smaller than that of $\ce{...
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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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What is really the number in the periodic table? [closed]

I learning basic chemistry and i have a doubt. I have this definitions Molar mass: Is the mass of $6.022\times10^{23}$ atoms of a chemical element and its unit of measurement is $\mathrm{g/mol}$. ...
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Solution for Electroplating Selenium?

I need to electroplate selenium onto a conductive metal (for an experiment). The end goal is a thin film of pure, elemental selenium. Unfortunately I can't find anything on the internet: Ideally, I'd ...
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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 ...
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Why is the number of covalent bounds typically formed by an element equal to 8 minus the group number? [closed]

Why would the number of covalent bounds typically formed by an element equal to 8 minus the group number? E.g for C, we have 8-4 bonds, for Cl, 8-7 bonds
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Exceptional electromagnetic properties of lanthanide series elements

Why do so many lanthanide series elements have exceptional electromagnetic properties? They can form strong magnets and are also used in superconducting applications. The number of elements in the ...
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Is it tennessINE because it has 117 electrons or because it behaves like a halogen?

The NPR News podcast and transcript The Convoluted Story Of How The First Atoms Of Tennessine Were Created includes the following exchange between science reporter Joe Palca and Oak Ridge nuclear ...
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How does a vitamin differ from a mineral [closed]

At the molecular level, I would like to know fundamentally how does a vitamin differs from a mineral. I understand both have, to say, Fe (Iron), then what exactly makes it a mineral Iron or a vitamin ...
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The "nose" of the periodic table [closed]

My teacher said that on the periodic table there is a "nose" formed by Al, Zn, Ag, and Cd. She said that they are all fixed charged (+3, +2, +1, and +2 respectively), and said that if I write them in ...
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Crystal structures of heaviest nuclides' compounds

What is the heaviest element of the periodic table for which there is a compound whose crystal structure has been completely resolved by X-ray diffraction?
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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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Why does period 3 of the periodic table contain 8 elements instead of 18?

Period 1 of the periodic table contains 2 elements ($1s^1$ and $1s^2$). Period 2 contains 8 elements ($2s^1$, $2s^2$, $2p^1$, $2p^3$, ..., $2p^6$). By the same argument, period 3 might contain 18 ...
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Isotopes and elements [closed]

this is a gold bar. If we look at its structure, will we see that there are atoms that have a different number of neutrons (aka isotopes) (as far as I'm concerned, an isotope is an atom with a ...
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Predicting atomic weight and density of calcium [closed]

I have a question from school: Assuming that the element Ca had not been discovered, predict using the properties of the known element surrounding Ca its own properties such as its atomic weight ...
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Why does zinc sulfide glow when hit by electrons? [duplicate]

In cathode ray tube experiment in order to check the direction of flow of electrons a hole was made in a note and behind it phosphorescent material zinc sulfide it was coated. Why does zinc sulfide ...
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Electrolysis of a calcium salt in polar aprotic solvent

If i found a calcium salt that is soluble in acetone or ethyl acetate, which are polar aprotic solvents, and attempted electrolysis, what would happen? Since polar aprotic solvents are used in metal-...
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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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"Estrontium" on poster

I was looking at a poster for an international chemistry olympiad. Its background contains some random elements as periodic table tiles. One of them said "Estrontium." A google search returned ...
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What is the most common element in the human body? [closed]

I was wondering that since H2O was 66% of the human body, hydrogen would be the most. But apparently carbon is. Can someone explain that?
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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 ...
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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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Does dilithium exist? [duplicate]

Lithium has two electrons in $\mathrm{1s}$, filling the first energy level; and one valence electron in $\mathrm{2s}$. Could two $\ce{Li}$ atoms form a bond to create $\ce{Li2}$; like $\ce{O2}$ or $\...
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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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