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Questions tagged [terminology]

For questions relating to terminology and naming conventions in chemistry.

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35 votes
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Why isn't ethane used for cooking?

We commonly use methane and propane for cooking (and home heating), but not ethane. I would expect ethane to be suitable for this, being in between the two, but I've never heard of anyone using it for ...
Joshua Frank's user avatar
31 votes
4 answers
10k views

Why is the Vitamin B complex, a "complex"?

I often come across the term "Vitamin B Complex" in my biology classes and innumerable times on the back of multivitamin packets, but what does the term "complex" here, even mean? I'm still in high-...
paracetamol's user avatar
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30 votes
3 answers
10k 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 ...
F'x's user avatar
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29 votes
4 answers
4k views

How 'heavy' should an element be, to be a "Heavy Metal"?

I've come across the term "Heavy metals" innumerable times in articles, mostly pertaining to environmental issues. Is there a weight range (of sorts) against which an element (metal) is classified as ...
paracetamol'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
23 votes
3 answers
5k 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 ...
DrCopeland's user avatar
22 votes
4 answers
5k views

A drop of water in a tin of sugar: Which one's the solvent, the sugar or the water?

The other day, when we were dealing with the chapter Solutions, our teacher asked us this: If I add a drop of water, to a tin full of sugar (without mixing it in), what's the solvent here? The ...
paracetamol's user avatar
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21 votes
4 answers
3k views

Is an isobar the same as an isotope?

I am a little bit confused about what an isobar is. Its online definition is that it's an element with the same number of neutrons but a different number of protons from an element $\ce{X}$. To me, ...
SpacePotato's user avatar
21 votes
7 answers
34k views

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 ...
Jeffery's user avatar
  • 227
21 votes
6 answers
239k views

What is the definition of of 'compound', 'mixture', 'element' and 'molecule'?

I am looking for the precise definitions, as I am very confused as to what they are exactly because although I mostly understand what they mean, I have encountered some conflicting definitions that ...
Sophia's user avatar
  • 219
20 votes
3 answers
10k views

Why is ammonium a weak acid if ammonia is a weak base?

$\ce{NH3}$ is a weak base so I would have expected $\ce{NH4+}$ to be a strong acid. I can't find a good explanation anywhere and am very confused. Since only a small proportion of $\ce{NH3}$ molecules ...
Clangorous Chimera's user avatar
20 votes
1 answer
6k views

Why is an ionic bond a chemical and not a physical bond?

Ionic bonds seem to be intermolecular but are classified as chemical bonds. "Ionic bonding is a type of chemical bond that involves the electrostatic attraction between oppositely charged ions.&...
Dylan Spano's user avatar
19 votes
3 answers
33k views

Do chemists refer to water as "dihydrogen monoxide"?

Is the name "Dihydrogen monoxide" actually what chemists would use to refer to $\ce{H2O}$ (assuming there was no common name, "water")? Of course, this is all over the internet. I'm a little ...
user4553's user avatar
  • 201
19 votes
2 answers
30k views

Is there a difference between equilibrium and steady state?

The term equilibrium is used in the context of reversible reactions that reach a point where concentrations no longer change. The term steady-state is used in enzyme kinetics when the concentration of ...
Karsten's user avatar
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19 votes
1 answer
2k views

What is a Herzberg?

Whatman lists the flow rates for their filters in a unit called a 'Herzberg': What is this? I've been searching around and I did find information about Herzberg flow rate testers, for example this ...
Jason C's user avatar
  • 1,172
18 votes
3 answers
40k views

Orthogonal Wavefunctions

My current understanding of orthogonal wavefunctions is: two wavefunctions that are perpendicular to each other and must satisfy the following equation: $$\int\psi_1\, \psi_2\, \mathrm{d}\tau =0$$ ...
user avatar
17 votes
2 answers
3k views

Does the term 'Cation' always refer to a positively charged particle?

From what I was taught in middle school, cations are those ions that move towards the cathode, likewise anions are those ions which move towards the anode. I didn't have issues with this back then, ...
paracetamol's user avatar
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17 votes
4 answers
4k views

Why "monoxide" but not "diodine"?

When naming compounds, sometimes when there are two vowels in a row the second is elided: this happens for example with "mono-oxide", which becomes "monoxide" instead. Why is this ...
Dan L's user avatar
  • 317
17 votes
2 answers
4k views

What does "René" mean in René alloys?

René alloys are nickel-based super alloys (René 41, René 88, René N5 etc. etc.). But how did it get the name René? Is it an acronym or contraction of other terms? It was created by Earl Ross and the ...
BlueAshFlyer's user avatar
16 votes
2 answers
20k 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.
SubZero's user avatar
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16 votes
2 answers
789 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 ...
user avatar
16 votes
1 answer
11k views

What is a stereochemically active or inactive s orbital?

In Concise Inorganic Chemistry by JD Lee (4th edition; adapted by Sudarshan Guha), page 73 under the section 3.6 (VSEPR Theory chapter Chemical Bonding): ...according to this theory, the position of ...
jyoti proy's user avatar
  • 1,014
15 votes
6 answers
17k views

Why do we call O2 oxygen? [closed]

I have been taught that oxygen is a chemical element, in other words a certain type of atom that has 8 protons in its nucleus. So why is O2 called oxygen? It is not a type of atom but rather a ...
user avatar
15 votes
2 answers
3k views

Why do most drugs (eg: oxycodone) have seemingly arbitrary names?

How do some medicines derive their names? For instance, is the name oxycodone somewhat arbitrary? I am not well-versed in Chemistry (1st semester student) but does the prefix oxy- imply some ...
user54747's user avatar
  • 423
15 votes
2 answers
1k views

Help understanding how "steric effects" are distinct from "electronic effects"?

@jakebeal's excellent answer to Why do animal cells “mistake” rubidium ions for potassium ions? includes the following passage: In the case of potassium versus sodium, which are both very important ...
uhoh's user avatar
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15 votes
1 answer
1k views

What is the analogue of "molecule" for ionic compounds?

In a system, if we have $\pu{18 g}$ of $\ce{H2O}$ ($M_\mathrm r = 18$), we can say we have a mole of water molecules or $6 \times 10^{23}$ molecules. But in another system, if we have $\pu{342 g}$ of $...
Dante R's user avatar
  • 161
14 votes
6 answers
10k views

What is a "hydrogen-like" or "hydrogenic" atom?

I'm studying some chemistry on my own in anticipation of the new school year and in my book, I came across the Rydberg equation for the first time. I worked through some examples and everything was ...
Melanie Shebel's user avatar
14 votes
5 answers
164k views

What is a neutral atom?

I was told that an atom's atomic number is defined as follows: The number of electrons or protons present in a neutral atom is called atomic number. It is represented by ...
Santosh Kumar's user avatar
14 votes
4 answers
84k views

What does it mean to shift equilibrium?

What does it mean to shift a chemical equilibrium? For example, the equilibrium shifts to the left … I don't understand that.
jaykirby's user avatar
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14 votes
3 answers
12k views

Is beryllium an alkaline earth metal?

For context: I got a question asking, "Which of the following alkaline earth metals do not give flame colour?". I quickly marked $\ce{Be}$ and $\ce{Mg}$ and got negative marks. The following is a ...
Aditya Dev's user avatar
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14 votes
2 answers
1k views

Etymology of "click chemistry"

According to Wikipedia, the term click chemistry was coined by K. Barry Sharpless in 1998. What does the word 'click' mean here? I guess it means "join" here but I'm not sure.
user48852's user avatar
  • 141
14 votes
4 answers
94k views

What is the difference between molarity and concentration?

I learned these two words in school but still I don't understand what the difference is between them. From my understanding, molarity and concentration means the number of moles in a certain solution. ...
Simon-Nail-It's user avatar
14 votes
2 answers
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 ...
Raphael J.F. Berger's user avatar
14 votes
1 answer
2k views

Is there a name for this algorithm to calculate the concentration of a mixture of two solutions containing the same solute?

There is an algorithm called "Mischungskreuz" (German for "x of mixing") that is sometimes taught as a shortcut to figure out the following problem: You have two solutions that ...
Karsten's user avatar
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14 votes
1 answer
1k views

In Hückel's rule, can n be any integer?

Hückel's rule says that any planar compound with a ring of conjugated p orbitals with $4n+2$ electrons is aromatic. Here, can $n$ be any integer, or does $n$ have to be related to the number of p ...
carbenoid's user avatar
  • 2,042
13 votes
5 answers
4k views

What is parachemistry? What does a parachemist do?

I was reading the Washington Post article An atomic town revels in its nuclear past as tunnel collapse raises contamination concerns and came across a quote from someone who was said to have been a "...
uhoh's user avatar
  • 5,898
13 votes
2 answers
26k views

Why is carbon dioxide considered a Lewis acid?

$\ce{CO2}$ is considered a Lewis acid. How it is an acid? According to Lewis: “species that accept an electron pair are acids”. But $\ce{CO2}$ can't accept electron pairs because oxygen and carbon ...
user40151's user avatar
  • 151
13 votes
3 answers
11k views

Clear definition of a 'non-oxidizing acid'?

From the Beryllium article in Wikipedia: Beryllium dissolves readily in non-oxidizing acids, such as $\ce{HCl}$ and diluted $\ce{H2SO4}$, but not in nitric acid or water as this forms the oxide. I ...
CowperKettle's user avatar
  • 3,276
13 votes
2 answers
3k views

What is "chemical pressure"?

While reading some publications on solid superconductors, I encountered a term "chemical pressure" a few times, which is usually attributed to the changes of superconducting transition ...
andselisk's user avatar
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13 votes
1 answer
805 views

What properties a compound should have to be called an "ice"?

I wonder what compounds are usually called "ice" and what properties do determine it? I can bring some examples of ice and not. Not ice: $\ce{H2S}$ cellulose sugar graphite lithium solid mercury ...
Anixx's user avatar
  • 1,488
12 votes
3 answers
5k views

Is an acid a salt or not?

In our office, we discussed today what the exact definition of a salt is and whether an acid itself can be classified as a salt. Our first problem was that we couldn't get a definitive definition for ...
gexicide's user avatar
  • 245
12 votes
3 answers
36k views

Difference between lab-grade and food-grade purity?

What is the difference in purity betwen lab-grade and food-grade when talking about potentially consumable compounds? As an example let's take ascorbic acid powder: if it's marked as lab-grade, does ...
Casper's user avatar
  • 375
12 votes
1 answer
7k views

What does “to the left” mean?

However, the concentration of hydronium and hydroxide ions will be very, very small; in fact, the equilibrium that's established in solution lies so far to the left, that only 18 in 1010 molecules of ...
user54747's user avatar
  • 423
12 votes
1 answer
1k views

How is the aromaticity in graphene different from the aromaticity in benzene?

The web page Aromaticity in Graphene and other 2-D Systems begins: I. Graphene While the σ-bonding in graphene is assumed to be a rigid honeycomb framework built out of two-center two-electron (2c-2e)...
uhoh's user avatar
  • 5,898
11 votes
1 answer
3k views

What is the scientific term to describe the operation of a bong?

What is the scientific term for the separation of dust particles from air by suction through a specialized flask in a way similar to the operation of a bong? The thing that led me to this was a ...
soundslikefiziks's user avatar
11 votes
3 answers
1k views

Should one pronounce “periodic” the same in “periodic acid” and “periodic table”?

In “periodic table”, the adjective is related to the noun period, and comes from Ancient Greek περίοδος through French périodique. In “periodic acid”, it is formed from the prefix per- and iodic (like ...
F'x's user avatar
  • 23.9k
11 votes
1 answer
415 views

What do these mineral classification symbols mean?

For my birthday I got an awesome mineral specimen case, as pictured below. What piqued my interest was the notations in the lid where the minerals are described with 5 specifications: C (obviously for ...
stib's user avatar
  • 425
11 votes
2 answers
4k views

Quick and simple explanation of molar mass, molecular mass and atomic mass

As a physics student, I hardly deal with such quantities and when I do, I blunder through. I think it’s a good time to be given a good explanation for these since I’m in a class of Nuclear physics. I ...
physkid's user avatar
  • 119
11 votes
1 answer
6k views

Is there a name for the opposite reaction to the dissolution?

When atmospheric $\ce{CO2}$ reacts with water to form $\ce{H2CO3}$, this is called dissolution, isn't it? What term would you use for the opposite reaction when it occurs at atmospheric pressure (e.g. ...
radouxju's user avatar
  • 223
11 votes
2 answers
239 views

What kind of chemical used in a chromatography run could be denoted with the letters D.H.?

A fellow translator is having trouble translating (into Russian) the mysterious D.H. abbreviation in the following passage: Slight variations of the ratio of the mobile phase constituents or ...
CowperKettle's user avatar
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