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40 votes

Does the mass of sulfur really decrease when dissolved in water and increase when burnt?

Upon reading the answers on Quora (thanks S007 for pointing that out) I realized this trick question is a lousy play upon two somewhat peculiar features of sulfur: When submerged in water (not "...
Ivan Neretin's user avatar
  • 31.2k
24 votes

If you put two blocks of an element together, why don't they bond?

Why, when you bring the two bars together so that they touch each other, do they not instantly bond with each other forming one larger bar or block? ... Why do we need to 'weld' two bars together - ...
hBy2Py's user avatar
  • 17.4k
21 votes

"Estrontium" on poster

"Estrontium" is not used as an element name in any language. It appears that the error traces to a single user by the name of Alejo Miranda (listed as from Ecuador) who has posted a large collection ...
Andrew's user avatar
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17 votes
Accepted

Can osmium react with oxygen at room temperature?

From Encylopedia Britannica: Of the platinum metals, osmium is the most rapidly attacked by air. The powdered metal, even at room temperature, exudes the characteristic odour of the poisonous, ...
Waylander's user avatar
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16 votes
Accepted

Why are some elements more abundant than others in the universe?

WHAT MAKES HYDROGEN ABUNDANT IN UNIVERSE: After few minutes of creation of the universe, protons and neutrons began to react with each other to form deuterium, an isotope of hydrogen. Deuterium, soon ...
Yb609's user avatar
  • 1,685
16 votes

How did Mendeleev know elements from compounds or mixtures?

Please do not underestimate the scientists of 19th century. They were as creative, intelligent and perhaps more genuinely dedicated to science than the scientists of the 21st century. Spectroscopy was ...
ACR's user avatar
  • 41.2k
14 votes
Accepted

Identification: was this gallium or mercury from broken thermometer?

Gallium, and Galinstan have the ability to wet glass, while mercury does not. So it's most probably gallium (or Galinstan).
aventurin's user avatar
  • 7,230
12 votes
Accepted

Chemical composition of seawater

The book that you're reading is measuring by mass. If you have pure water then you would expect oxygen to make up $\frac{16}{16 + 2}\times 100\% \approx 89 \% $ by mass. Likewise, hydrogen would ...
PJ R's user avatar
  • 1,394
12 votes
Accepted

Elements other than carbon that can form many different compounds by bonding to themselves?

Is carbon the only element that can do this? No, carbon is not the only element with such characteristics. If not, then what are the other elements can also do this? There is a whole number of ...
user79161's user avatar
  • 484
11 votes
Accepted

Why is UuX used as a symbol for unnamed elements on the periodic table?

In 1978, the IUPAC Commission on the Nomenclature of Inorganic Chemistry decided that it would be necessary to have a systematic naming for the elements with atomic number greater than 100, even for ...
ringo's user avatar
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11 votes
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Confusion over boiling point of gallium

This question has been recently raised in Chemistry & Engineering Letters. The CRC Handbook (2017) in section "MELTING, BOILING, TRIPLE, AND CRITICAL POINTS OF THE ELEMENTS" [1, p. 4-117] lists ...
andselisk's user avatar
  • 38.3k
11 votes

Elements which do not form oxides

The first thing that came to mind is oxygen itself, as the term "oxide" suggests one other element in its chemical formula. Merriam-Webster suggests a more strict version: "a binary compound of oxygen ...
andselisk's user avatar
  • 38.3k
11 votes

Can osmium react with oxygen at room temperature?

As the others already stated, handling pure Osmium is too dangerous at home, but there are shops that offer small samples of elements sealed in acrylic glass, which is supposed to be safe. Maybe this ...
Eldrad's user avatar
  • 211
10 votes

Is there a way to contain fluorine gas for long term so that it can be visually observed?

Here's a slightly exotic, expensive solution: solid, crystaline $\ce{CaF2}$ tubing will do the job. How to get the gas inside, then make a glass seal, is a bit of a challenge though. Surfaces can be ...
uhoh's user avatar
  • 5,898
10 votes
Accepted

Macgyvering a Spectroscope

The medieval "nerd" in a D&D campaign might use acids to get minerals into solution. Sulfuric acid ($\ce{H2SO4}$, vitriol oil) was initially prepared by heating iron(II)-sulfate ($\ce{FeSO4 ยท 7 ...
Klaus-Dieter Warzecha's user avatar
10 votes
Accepted

Meaning of m2 in the symbol for an isotope of an element

As per this Wikipedia page on isotopes: The letter $m$ is sometimes appended after the mass number to indicate a nuclear isomer, a metastable or energetically-excited nuclear state (as opposed to the ...
Todd Minehardt's user avatar
10 votes

Chemical composition of seawater

As it has already been mentioned, these are mass percentages, which are a bit imprecise. For the reference, CRC handbook of chemistry and physics [1, p. 14-17] lists elements' abundances in seawater ...
andselisk's user avatar
  • 38.3k
10 votes

Can osmium react with oxygen at room temperature?

According to Wikipedia: Finely divided metallic osmium is pyrophoric[1] and reacts with oxygen at room temperature, forming volatile osmium tetroxide. Some osmium compounds are also converted to the ...
Oscar Lanzi's user avatar
10 votes

Why is Gallium-69 stable, Gallium-70 unstable and Gallium-71 stable again?

There is the general neutron/proton ratio rule, regarding stability of nuclides, described by the Valley of stability. Additionally, in beta decay context, there are 3 easily remembered rules, based ...
Poutnik's user avatar
  • 42.3k
10 votes

Elements with most commonly occurring isotope being different from the most stable one

Yes. You're probably thinking about comparing nuclear stability by comparing radioactive decay half-lives, which is a reasonable and intuitive (though somewhat limited) criterion. Already here there ...
Nicolau Saker Neto's user avatar
9 votes
Accepted

Chemical elements or compounds with yellowish white color

Aluminium(III) chloride - often described as white but samples is sometimes contaminated with iron(III) chloride giving it a light yellow color Antimony(V) oxide - pale yellow solid Bismuth(III) oxide ...
Nilay Ghosh's user avatar
  • 26.2k
9 votes
Accepted

How many elements have been identified for which there are no known spectral lines?

How many elements have been identified for which there are no known spectral lines? tl;dr: Eighteen, or all of them above A=100. One place to start is a 2015 article by H. Backe et al. in Nuclear ...
Jon Custer's user avatar
  • 8,600
9 votes
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How many carbon, hydrogen, oxygen, nitrogen, and phosphorus atoms are there in the observable universe?

Two key numbers can be estimated from known observable things in astronomy (and cosmology where current big bang models explain the processes that created the "light" elements and their ...
matt_black's user avatar
8 votes
Accepted

Why don't we see these lanthanide species?

This is really the exact same question but just in a different context of transition metals: Cr(II) and Mn(III) - their oxidizing and reducing properties? The answer is because exchange energy (which ...
orthocresol's user avatar
  • 71.5k
8 votes
Accepted

Why doesn't Sodium (Na) form duplet?

Well, sodium does have non-zero electron affinity, so it surely can acquire another electron, provided it can get one for free. That's what happens when a lone sodium atom meets a lone electron ...
Ivan Neretin's user avatar
  • 31.2k
8 votes
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Extracting sulphur from hot springs with medieval technology?

Sulfur does naturally occur around hot springs and volcanos. It would be very reasonable to assume that a hot spring could have natural deposits of sulfur near it that could be collected without any ...
A.K.'s user avatar
  • 12.6k
8 votes

Element Names in English

There are several reasons for this, one of which is the pigeon-hole effect. The English language consists of only 26 letters, while nature contains more than 90 elements. The letters would become ...
ACR's user avatar
  • 41.2k
8 votes
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Very Little Astatine

It's true that astatine is radioactive and it will vaporize by its own radiation. Not to mention its very low half-life (8.1 hours), meaning it will lose half of its mass before you even try to detect ...
Nilay Ghosh's user avatar
  • 26.2k

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