Questions tagged [nomenclature]

This tag should be used for questions about the naming of compounds and elements, usually using systematic names according to IUPAC recommendations, but also using retained traditional names.

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53
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3answers
8k views

Why do we write NH3?

We've learnt that the electropositive element is written first. Then why is ammonia written as $\ce{NH3}$ ?
50
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6answers
55k views

Is carbon dioxide organic or inorganic?

Today in chemistry class we were discussing Organic Chemistry. We discussed what organic compounds basically are and then I asked the teacher whether $\ce{CO_2}$ is organic or not. She told that it is ...
44
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4answers
43k views

Why do the names of most chemical elements end with -um or -ium?

Why do the names of most chemical elements end with -um or -ium for both primordial and synthetic elements?
41
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1answer
4k views

Why is methane's molecular formula conventionally “CH₄”, while water is “H₂O” (among others)?

While revisiting some of my old notes about the Miller-Urey experiment, I stumbled across the "equation"... Electricity + $\ce{CH4~/~ NH3~/~H2O~/~CO}$ = Amino Acids This got me thinking. ...
38
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2answers
7k views

Why is arsenous acid denoted H3AsO3?

Inspired by this question, I'm wondering why arsenous acid is frequently denoted $\ce{H3AsO3}$, as opposed to $\ce{As(OH)3}$, which would appear to more accurately reflect its connectivity? [edit] I ...
35
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2answers
1k views

IUPAC nomenclature for an interesting looking organic compound

How can I name this organic compound while adhering to the IUPAC standards?
33
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4answers
5k views

Why are isotopes of hydrogen the only ones with special names?

Why does no other element but hydrogen get special names for its isotopes?
32
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5answers
7k 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 ...
31
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3answers
16k views

IUPAC nomenclature: “Smallest sum of locants”?

While naming any compound, the numbering should be done such that position of substituted groups gives smallest sum. I'm struggling with the IUPAC naming for cyclic compounds. How exactly does this ...
29
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2answers
20k views

What do the prefixes meta, ortho, pyro mean in inorganic chemistry?

In inorganic chemistry, when is the prefix meta used? (as in metaborate and metasulphite) What about the terms pyro and ortho (as in orthophosphorous acid)? For example, I recently came to know about ...
29
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4answers
8k views

Is activated carbon classified as organic or inorganic?

Organic compounds are typically defined as “molecules containing carbon”. Wikipedia states that there for some historical (read: non-logical) reasons, a few types of carbon-containing compounds ...
26
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3answers
2k views

How to assign E/Z configuration according to the Cahn-Ingold-Prelog rules when subsituents differ only by stereochemistry

I stumbled-upon this compound: I'm wondering how to determine the configuration of the double bond. Is it E or Z? How do I decide on the priorities when the substituents can only differ in the ...
25
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1answer
3k views

How to name binary (inorganic) compounds given their chemical formula, and vice-versa?

I wish to understand how to name binary (inorganic) compounds when given their formula. When I am a given compound like $\ce{B2F2}$ or $\ce{N2O4}$, I have little to no clue on how to write their ...
25
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2answers
6k views

What is the IUPAC nomenclature of alkane with large numbers of C atoms (more than 200)?

What is the IUPAC nomenclature for alkanes with large numbers of $\ce{C}$ atoms (more than 200)? For example, what is the IUPAC accepted name for $\ce{C_{205}H_{412}}$?
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2answers
3k views

Does IUPAC nomenclature have the ability to name all organic compounds?

We all know about IUPAC nomenclature. There are rules to name straight chain compounds, cyclic ones, polycyclic ones, ones with functional groups, and so on. But I have come across several examples of ...
24
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2answers
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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: ...
23
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4answers
4k views

What is a word for “atom or molecule”?

What is a word for "atom or molecule"? As in: "The entry of an atom or molecule across a cell membrane into a cell is dependent on its size and solubility." This keeps coming up, and it's really ...
23
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2answers
3k views

Cubane systematic name

Why is cubane called pentacyclo[$4$.$2$.$0$.$0^{2,5}$.$0^{3,8}$.$0^{4,7}$]octane? I am especially intrigued by the pentacyclo part.
23
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1answer
974 views

What is the meaning of the “-osic” suffix on a metal (e.g., cobaltosic oxide)?

I just came across the term cobaltosic for the first time in the abstract of Ind Eng Chem Res 52(18): 6076, 2013 (emphasis added): A nanocomposite of cobaltosic oxide and nitrogen-doped graphene ($\...
23
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2answers
37k views

Is the nomenclature “primary”, “secondary”, “tertiary”, and “quaternary” carbon atoms limited to sp3 carbon atoms?

In organic chemistry we can classify carbon atoms as primary, secondary, tertiary, or quaternary based on the number of additional carbon atoms bonded to the carbon atom of interest. The definitions ...
22
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2answers
7k views

What does lowercase r-s notation mean?

I came across a naming convention which I haven't seen before. I let ChemDraw name the following compound for me and got a name containing lowercase "r" and "s" configurations. Can someone tell me ...
21
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2answers
135k views

What is the difference between D and L configuration, and + and −?

What is the difference between D and L configuration, and + and −? My textbook says they are two different things. It also says that the correct way to name glucose is D(+)-glucose. Could someone ...
21
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2answers
5k views

Is the ring or the chain chosen as the parent structure in octan-2-ylbenzene?

How would you name the above compound according to IUPAC rules? I see some sources say it is 2-phenyloctane, but ChemDraw and a few other sources say it is 2-octanylbenzene.
20
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2answers
7k views

A monocyclic 6 carbon ring with 6 double bonds

I would like to know if this molecule has ever been synthesized, if not why not, and what would its IUPAC name be?
20
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2answers
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Usage of ammine vs amine in nomenclature

In the nomenclature of complex salts we use ammine for NH3 instead of amine. I thought this was to differentiate between ammine ligand and amine in organic ligand (like en). However, Wikipedia ...
20
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2answers
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What does dl- mean in nomenclature

I came across the compound dl-stilbene dibromide, and I am confused by exactly what this means. I thought it might have meant a racemic mixture but there is only one chemical structure given.
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2answers
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Do the names of some elements have anything to do with planets?

There are elements like neptunium and plutonium in the periodic table. Did their discovery have anything to do with Neptune and Pluto? Or are they randomly assigned with such names?
18
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6answers
722 views

Organic Structure Challenge

Recently we had this challenge in our Organic Chemistry Department. I was not involved in it but I thought it might be interesting for the SE Chemistry site, so here it is. Propose a structure for ...
18
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2answers
867 views

Why do we not generally have “enneane”?

Most numerical prefixes are based on Greek roots, but for "nine" we use the Latin root instead which seems inconsistent. Thus, for instance, "nonane" instead of "enneane", or in mathematics "nonagon" ...
18
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1answer
794 views

What does the newest IUPAC nomenclature have against unsaturation?

IUPAC nomenclature 2013 changed a couple of rules very commonly used in naming simple acyclic compounds. As a result, depending on which nomencalture we choose, the answer to this question varies ...
17
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2answers
15k views

Does water have a chemical name?

Does water have a chemical name? If so, what is it? P.S. I checked up the web and got all sorts of crazy answers like dihydrogenmonoxide, oxidane, hydrogendihydride etc. Please validate.
17
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1answer
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What is Fjord Region?

I'm studying molecular motors for a project of mine and I'm trying to understand what a Fjord region is. It's sort of labeled in the image below but I'm not entirely sure which part. I would like ...
17
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1answer
443 views

How to name this quintuply-bonded chromium dimer?

Depicted below is a chromium compound with a metal–metal quintuple bond. It boasts two identical bridging ligands, derivatives of 1,3-diphenylbenzene. The aim of this question is to figure out the ...
16
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3answers
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IUPAC name for 1,2,3-trichlorocyclopropane?

What is the IUPAC name for the two isomers of 1,2,3-trichlorocyclopropane? Similarly what is the name for isomers of 1,2,3,4-tetrachlorocyclobutane, 1,2,3,4,5-pentachlorocyclopentane, etc? 1,2,3-...
16
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2answers
657 views

Etymology of alanine

Oxford dictionary online gives etymology of alanine as: Coined in German as Alanin, from aldehyde + -an (for ease of pronunciation) + -ine. But I see no resemblance to the aldehyde structure in ...
16
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1answer
4k views

What is the IUPAC systematic name for methane?

The 1993 IUPAC Blue Book claims that "methane" is a semisystematic name: Semisystematic names also exist, such as "methane", "propanol", and "benzoic acid", which are so familiar that few chemists ...
16
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1answer
2k views

How to name this cyclic compound with an O in it?

How to name this cyclic compound with an O in it? I was going to name it cyclobutane, but not all of the atoms making up the ring are carbons, one is an oxygen. So, then I decided to name it butane, ...
16
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1answer
784 views

Alphabetization rule in case of consecutively placed substituents

This is the compound: I am stuck on assigning the locants to the given halo substituents. We know that all halogens are of equal priority. So, using first point of difference, we get either an $\ce{I ...
16
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1answer
4k views

How are non-carbon stereogenic centers named (S/R)?

The R/S naming system for stereocenters relies on the Cahn–Ingold–Prelog priority rules to rank the four substituents of a stereocenter; the R or S name is then attributed depending on the spatial ...
16
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1answer
346 views

Is there a preferred way of naming the resonance hybrid in keto-enol tautomerism?

While answering a question about keto-enol tautomerism the question arose, how can I refer to the resonance hybrid instead of on of the resonance forms. In the case of the deprotonated butane-2-one, I ...
16
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2answers
357 views

What is the IUPAC preferred name of this tetracyclic natural product?

On page 819 of Vollhardt, Organic Chemistry 7th Ed., the following "subunit of the antibacterial platensimycin" appears. I have attempted to apply von Baeyer and skeletal replacement ('a') ...
15
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3answers
2k views

Pubchem, InChI, SMILES, and uniqueness

PubChem compound 6140 is L-phenylalanine in its neutral (not zwitterionic) form. According this PubChem, this molecule has the following SMILES and InChI indentifiers: SMILES: C1=CC=C(C=C1)CC(C(=O)O)...
15
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2answers
998 views

Why is this compound named resorcinol?

Substituted phenols or polyhydroxy phenols have their general name apart form IUPAC names. The general names comes from the source it is found like:- Catechol (1,2-dihydroxybenzene)- obtained from ...
15
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1answer
2k views

Why is a temporary name given to an element with an atomic number above 100?

All the elements with an atomic number more than 100 are given temporary names by IUPAC according to nomenclature rules. For example, element 101 was temporarily named "Unnilunium" until they give it ...
15
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7answers
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Which is anode and which is cathode?

A maybe (hopefully) simple question about the denotations of "anode" and "cathode". The below image is a schematic of a polymer solar cell (Source (WBM)). (The figure text is quoted as well for the ...
15
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1answer
611 views

IUPAC name of C₆(CH₃)₆²⁺

What is the correct IUPAC name (or least incorrect one, if the current rules can't precisely describe that) of the interesting species $\ce{[C6(CH3)6]^{2+}}$ (which is extensively discussed here), ...
14
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3answers
695 views

Can geometrical isomers be enantiomers?

I have just been pondering upon the question above. I have found this example and I am sure they are enantiomers, but do they also count as geometrical isomers?
14
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2answers
3k views

Etymology of saturation degrees (-ane, -ene, -yne) in aliphatic compounds

I like to know where the names for saturated, unsaturated double, and unsaturated triple bonded aliphatic compounds came from. What is the reason/etymology behind the suffix -ane, -ene, and -yne? I ...
14
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1answer
814 views

Why was Lawrencium's symbol changed?

The initial proposal by Lawrence Berkeley National Laboratory scientists for naming element 103 was "Lawrencium" with the symbol "Lw", However, while IUPAC accepted the name "Lawrencium" for the ...
14
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1answer
2k views

Is it correct to say that ethenol is an alcohol?

IUPAC Gold Book defines alcohols as: Compounds in which a hydroxy group, $\ce{–OH}$, is attached to a saturated carbon atom $\ce{R3COH}$. However, Wikipedia says that: Vinyl alcohol, also ...

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