Questions tagged [history-of-chemistry]

Questions regarding the development and exploration of chemical ideas, innovations, and discoveries.

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How were elements and molecular formulæ determined in the old days?

Before modern chemical techniques, say in the 19th century and earlier, how did (al)chemists determine whether a substance was an element or a compound? If it was a compound, how did they determine ...
Nick's user avatar
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7 votes
1 answer
546 views

Can molecular structure be determined without modern characterization methods?

Molecular composition can be determined in some "primitive" ways (1, 2). What about the molecular structure? Is there a way to know what's bonded to what without spectroscopy etc.? By "modern" I mean ...
Sparkler's user avatar
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11 votes
4 answers
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How were the elements discovered before modern technology?

I recently was in need of zinc for an experiment. So I resorted to obtain it from some dry cell. But I wondered if it was pure zinc or was it $\ce{ZnO2}$ or any other compound of $\ce{Zn}$. It then ...
karthikeyan's user avatar
10 votes
1 answer
11k views

Why are there 3 columns in Group VIII of the Periodic Table?

I'm currently reading in-depth about the layout of the Periodic Table, and I wondered why the table has 3 columns in its Group VIII: As I understand, this is an old notation of the table, now ...
CowperKettle's user avatar
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6 votes
1 answer
475 views

How were the first molecular formulas determined?

How were molecular formulas determined before spectroscopy and spectronomy? I know that John Dalton thought that the formula of water was "HO" but we now know it to be "H2O." How did Dalton even know ...
Dissenter's user avatar
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33 votes
4 answers
16k views

Where did amino acids get their one-letter codes?

Some amino acids have a one-letter code that's just the first letter of the name of the amino acid. This makes sense and obviously, since there is more than one amino acid that begins with the same ...
Melanie Shebel's user avatar
20 votes
4 answers
4k views

What is the origin of the "positive-to-negative" convention concerning dipole moments in chemistry?

I'm a physics professor who often teaches students who have taken a lot of chemistry (read: pre-meds). In physics, the dipole moment of a charge configuration is defined as pointing from ...
Michael Seifert's user avatar
16 votes
1 answer
768 views

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, ...
Paddyseo's user avatar
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14 votes
2 answers
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Effect of enatiomers in pharmaceuticals [closed]

Often (or always?) one enantiomer of a certain drug will be effective and the other ineffective or harmful. The famous example is thalidomide, where one enantiomer caused mutilation of the unborn ...
RobChem's user avatar
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11 votes
1 answer
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Were gold(II) complexes synthesized for the first time in 2017?

Recently in the Google news feed, I discovered this news: Gold stabilized in very rare oxidation state +II Missing golden link found: Divalent gold complex isolated for the first time in a ...
Nilay Ghosh's user avatar
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8 votes
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Origin of "ortho", "meta", "para"

Definition The ortho position refers to the two adjacent positions on a benzene ring. The meta position refers to the positions separated by one carbon atom on a benzene ring. The para position ...
DHMO's user avatar
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5 votes
1 answer
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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 ...
Andrey Mikhaylov - lolmaus's user avatar
5 votes
1 answer
1k views

Why would tellurium + sodium hydroxide have worked as a good anti-knock gasoline additive (if it wasn't so smelly)?

The April 22, 2022 Veritasium video The Man Who Accidentally Killed The Most People In History mentions several aspects of the historical use of tetra-ethyl lead in gasoline, the resulting widespread ...
uhoh's user avatar
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3 votes
2 answers
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According to what criteria was the periodic table of elements ordered?

I was wondering why the elements in the periodic table were disposed the way they are. I understand, of course, that they are put in increasing atomic number fashion, but I'd like to know more about ...
Adrian's user avatar
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2 votes
1 answer
27k views

What is the first organic compound to be discovered ? Urea or alloxan?

It is widely accepted that urea is the first organic compound to be synthesized from inorganic chemicals. Wikipedia states that: In 1828, the German chemist Friedrich Wöhler obtained urea ...
Nilay Ghosh's user avatar
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2 votes
1 answer
2k views

How did early chemists measure mass of atoms?

Here a book says that Berzelius measured atomic masses using a simple lab and his measurements was so close to modern results. Can someone explain how a person living in 19th century was able to ...
Turkhan Badalov's user avatar
2 votes
0 answers
194 views

What dodecahedral molecule is Linus Pauling likely holding in this photograph? Does it have 40 carbon atoms? [closed]

The video Quasicrystals ; Prof. Daniel Shechtman ; Nobel Prize in Chemistry focuses on Professor Dan Shechtman but happens to include some photos of Linus Pauling who never believed in quasicrystals. ...
uhoh's user avatar
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28 votes
3 answers
1k views

What makes a radical 'free'?

The qualifier 'free' seems to be ubiquitously attached to discussion of radicals as highly reactive species with unpaired spins. What, precisely (or imprecisely, as the case may be) does 'free' really ...
Richard Terrett's user avatar
27 votes
2 answers
7k views

Why are the rare earths erbium (Er), terbium (Tb), yttrium (Y) and ytterbium (Yb) named like that?

I know the history of the discovery of the rare earth elements, that they were discovered near the village Ytterby in Sweden in the 19th century. Four elements are directly named after that village: ...
Gimelist's user avatar
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22 votes
4 answers
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Why was Avogadro's number chosen to be the value that it is? [closed]

I understand that the mole is an extremely useful way of measuring and understanding atomic quantities. I did find some history of the number in its wikipedia article, but I did not find an answer to ...
Lucas Willhelm's user avatar
15 votes
3 answers
2k views

When did the atom theory become indisputable?

We know that the Greeks were the first scientists (or better, philosophers) to introduce the idea that matter is made up of little “chunks”, and they named these chunks “atoms”. This idea that matter ...
Hosenberg's user avatar
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15 votes
1 answer
7k views

Why do some element symbols contain a single letter while others contain two letters?

As the title says, why do some element symbols contain a single letter while others contain two letters?
Endy Sun's user avatar
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14 votes
7 answers
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Why lanthanides and actinides are shown separate from standard Periodic Table layout?

In the standard Periodic Table layout , all the elements up to 56 are in order i.e are in the same layout table. However, lanthanides and actinides are always shown separately from the layout like in ...
SRy's user avatar
  • 251
10 votes
1 answer
224 views

Before the CIP system was created, how did chemists ensure that the D/L system matched the R/S assignments?

The ᴅ/ʟ system I have referred to is the one chemists used before the Cahn-Ingold-Prelog (R/S) system where they arbitrarily assigned the (+) and (-) isomers of glyceraldehyde, 'ᴅ' and 'ʟ' ...
user25714's user avatar
  • 197
10 votes
1 answer
14k views

Democritus vs John Dalton atomic theory

What is the difference between atomic theory given by Democritus and John Dalton? Because I have read in many books and figured out that both theories explain the same i.e atom is an indivisible ...
AksaK's user avatar
  • 1,005
9 votes
1 answer
2k views

Why are Erlenmeyer flasks shaped the way they are?

The title says it all. We could conceive a good number of other possibilities. Why did Erlenmeyer arrive at this design?
docscience's user avatar
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8 votes
2 answers
428 views

How did Joseph-Louis Proust know what gases weighed?

Proust's work led him to conclude that compounds always contain the same ratio, by weight, of their constituent elements. How did he know (or deduce?) what gases weighed? Precise answers appreciated ...
Ali's user avatar
  • 91
7 votes
1 answer
3k views

How to determine the structure of organic molecules without spectroscopy [duplicate]

I wonder how chemists worked out the structures of organic molecules before spectroscopy (especially NMR) was invented? Surely, we could do functional group tests, but the correct connection of atoms ...
Nissa's user avatar
  • 419
6 votes
1 answer
2k views

Was Wöhler’s urea synthesis carried out with or without oxygen?

I learnt and was very impressed by the urea synthesis by Wöhler in 1828. The reaction was the heating of ammonium cyanate. One of my textbooks in the library said that ammonium cyanate was heated ‘in ...
PandoraU.U.D's user avatar
6 votes
3 answers
3k views

How was the diatomic nature of many common gaseous elements originally determined?

How did scientists find out that $\ce{Cl2, H2, O2}$ atoms have a two-atomic molecular structure ?
LeDuc's user avatar
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6 votes
1 answer
6k views

What is the significance of Law of Multiple Proportions?

I cannot understand how the Law of Multiple Proportions is significant, or how does it further improve over Law of Conservation of Mass or Law of Definite Proportions. From Wikipedia: If two ...
Utku's user avatar
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6 votes
1 answer
556 views

Did Berzelius unify the names of chemical elements using the Latin language?

I asked this question because the Chinese Wikipedia community is trying to decide whether it should use Latin names or IUPAC names for the first introductory sentence for its articles on chemical ...
Han-Teng Liao's user avatar
4 votes
1 answer
755 views

How was Mendeleev able to develop his table?

I asked my general chem instructor this and he didn't know: Mendeleev was able to group elements and discovered a bunch of them and put them in the correct order in the mid-1800s. What equipment did ...
g33kz0r's user avatar
  • 141
3 votes
2 answers
168 views

Discovery of elements

How did the first chemists know that a sample contained so and so elements? If they tried to find through reactions,they should know what elements make up the other reactant(s), and how it reacts ...
P.K.Harshith's user avatar
3 votes
1 answer
196 views

How long does it take to replicate Friedrich Wohler's synthesis of urea?

I’m an author, writing a story where a doctor from modern day gets dropped into the late 1800s in California. They need urea to help a patient. Friedrich Wohler's synthesis of urea happened before ...
Kyros's user avatar
  • 31
3 votes
1 answer
2k views

On the periodic table: Why are groups of elements organized by 'letter' [duplicate]

Why are the groups of elements on the periodic table organized into areas represented by the letters s,p,d,f,g, and h? What does this mean?
pandalarry's user avatar
2 votes
1 answer
162 views

Thought process behind Rutherford's gold foil experiment

In Rutherford's gold foil experiment, if he at first thought the atom looked like the plum pudding (as Thomson had said), why did he think the alpha particles would not be repelled by the positive "...
suse's user avatar
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