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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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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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 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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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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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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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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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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Does any element have nutritional (caloric) value?

Is there any single element (e.g. possibly carbon) that can be eaten, which has a nutritional value such that it provides calories? I found on Wikipedia (dietary element) that there are certain ...
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Confusing Lines About Extinct Elements

In "The Greatest Show On Earth", author Richard Dawkins spends a chapter discussing radiometric dating. I find myself confused by the following lines, though I'm sure the reason is elementary. (...
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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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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 radioactive elements emit alpha beta and gamma rays

I am confused about this that why radioactive elements emits alpha beta and gamma rays WHILE other elements can't do so.
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Liquid fertilizer nutrient values - % weight by weight or % weight by volume?

I was convinced that liquid fertilizer labeling use the % weight by volume convention. However now I bought a magnesium-sulfur based additive. The label clearly uses % weight by weight. Weight by ...
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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 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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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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What is the difference between metaphosphoric acid and phosphonic acid?

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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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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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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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 ...
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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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Why does technetium not exist in nature?

Why does technetium not occur in nature? It is the only element before bismuth to net exist in nature. What's the reason for that?
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Can you calculate the properties of a substance based solely on its atomic properties?

I'm trying to write some software that I can use to determine, roughly, what the physical properties of a pure substance are. I know I could just use a database of the known properties of each element,...
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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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How to Determine An Element's Colour

Different elements have different colours. Some elements may have similar colours like Sodium (Na) and Potassium (K), so that's why i'm asking "is there a way to calculate or even simply deduce the ...
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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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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 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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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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1answer
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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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Memorizing the periodic table

Several people have said that the key to understanding chemistry is through memorizing the periodic table. I want to ask if there is a simple technique to learn it, or if I just have to remember ...
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Doubt on 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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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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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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“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 true depiction of the periodic table?

Normally with the periodic table the lanthanide series is separated out because it's long and would make the table wide. I looked for an expanded version and found this: I found it kind of strange ...
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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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