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 "...
- 31k
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 - ...
- 17.3k
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 ...
- 10.1k
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, ...
- 21.6k
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 ...
- 1,665
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 ...
- 39.1k
14
votes
What is the difference between "molecular mass", "average atomic mass" and "molar mass"?
Atomic mass refers to the average mass of an atom. This has dimensions of mass, so you can express this in terms of daltons, grams, kilograms, pounds (if you really wanted to), or any other unit of ...
- 71.1k
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).
- 7,142
13
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 ...
- 486
12
votes
Accepted
Why does technetium not exist in nature?
Technetium does occur in nature. From the Los Alamos page on technetium:
Technetium was the first element to be produced artificially. Since its discovery, searches for the element in terrestrial ...
- 10.6k
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 ...
- 1,394
11
votes
Why is gold so popular in nanotechnology?
First, let's look at gold's properties.
Gold is the most malleable of all metals. This malleability alone is very useful in aiding scientists to create such small gold nanoparticles.
Gold also ...
- 154
11
votes
Accepted
At what temperature (in kelvin) are most of the elements on the periodic table liquids?
Now that's a great question indeed! Evidently, at 0K all elements except helium are solids, at 10000K they are all gases, so someplace in between the number of liquids must reach a maximum; what and ...
- 31k
11
votes
Accepted
Confusing Lines About Extinct Elements
Defintions
Occur on Earth differentiates between all isotopes in the universe and isotopes which exist or have existed on Earth. The passage identifies that there are a total of 308 isotopes ...
- 327
11
votes
Accepted
Can we recycle garbage with the principles of mass spectrometry?
Yes it is possible, but is very expensive and would be orders of magnitude more costly than what people are willing to pay for recycled materials. Let me give two data points to explain why it is ...
- 21.8k
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 ...
- 23.9k
11
votes
Accepted
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 ...
- 37.4k
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 ...
- 37.4k
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 ...
- 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 ...
- 5,742
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 · 7 ...
- 43.8k
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 ...
- 10.6k
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 ...
- 37.4k
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 ...
- 39.2k
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 ...
- 25.2k
9
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 ...
- 53.2k
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 ...
- 8,289
9
votes
Accepted
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 ...
- 35.5k
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