51

I think what you may find most helpful is to know a bit of the history of element discovery and atomic theory. The first pure substance containing only the element oxygen to be isolated was dioxygen ($\ce{O2}$), in 1774, though it was called "dephlogisticated air" until 1777 when Lavoisier used the term "oxygen" for the first time. This was some 30 years ...


50

Probably the biggest drivers behind using methane as a fuel is that it is abundant in natural gas and is (currently) mostly useless as a chemical feedstock. Ethane makes up a few percent of natural gas and can also be obtained as byproducts of petroleum refining, but the big difference from methane is that ethane is extremely useful in chemical synthesis (...


38

TL;DR IUPAC hasn’t made up their mind, but plain old water appears to be an appropriate name. However, chemical derivatives of water may not be named using water. In Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 it is stated (P-21.1.1.2) that The common names water, ammonia, [...] are used in these recommendations but ...


37

In both cases, there appears to be a confusion of terminology between common and technical uses. 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 this purpose. Why is that? In reality, anyone using ...


32

Yes, cations always have a positive charge and anions always have a negative one. The difficulty is that the term cathode and anode do not always correspond to the same pole. The cathode is that pole of an electrolytic/electrochemical cell where reduction takes place (cathodic reduction) while the anode is where oxidation takes place (anodic oxidation). ...


32

Not quite, an isotope has same number of protons ($ A- N = Z = \mathrm{constant}$), but a different number of neutrons ($\mathrm N$ varies; e.g. $\ce{^3_\color{red}{1}H}$ and $\ce{^2_\color{red}{1}H}$, or $\ce{^235_\color{red}{92}U}$ and $\ce{^238_\color{red}{92}U}$ are isotopes). An isobar has a fixed number of total nucleons ($Z + N = A = \mathrm{constant}...


27

There is no true, accepted definition of heavy metal. I was taught to apply the option a metal that has density equal to or over $5.0\ \mathrm{g/cm^3}$. Other variants include a different density range, specific gravity over density, environmental impact, atomic number, toxicity, or atomic mass, even chemical properties. See here$^{[1]}$ for further ...


25

First, let’s get the definition of weak and strong acids or bases out of the way. The way I learnt it (and the way everybody seems to be using it) is: $\displaystyle \mathrm{p}K_\mathrm{a} < 0$ for a strong acid $\displaystyle \mathrm{p}K_\mathrm{b} < 0$ for a strong base $\displaystyle \mathrm{p}K_\mathrm{a} > 0$ for a weak acid $\displaystyle \...


24

While nomenclature is of particular interest to organic chemists to specify an exact compound, the classification of X into broad category Y or Z isn't a precise science, and not really of practical use. The article cites a textbook by Seager to this effect, stating The distinction between "organic" and "inorganic" carbon compounds, while "useful in ...


23

You could imagine stirring the sugar enough for the water molecules to be uniformly distributed throughout - it would then be homogeneous. However, even then, to refer to the mixture as a solution of water in sugar is unhelpful, not least because referring to a slightly damp solid as a solution will only confuse. A definition needs to be useful, as well ...


22

In the original German paper [1] Adolf Strecker used Aldehyd-Ammoniak or aldehyde-ammonia as a precursor, that's where the name derives from: Vor einigen Jahren habe ich gezeigt, daſs Aldehyd-Ammoniak und Blausäure beim Erwärmen mit verdünnter Chlorwasserstoffsäure sich zu einer schwachen Basis, Alanin genannt, vereinigen [...]: $$\ce{\underset{\text{...


21

There is no chemical difference, only a psychological one: how do you think about it. They are both the same thing, but many people associate $\ce{H+}$ ions with chemical reactions and protons with particle physics. A hydrogen atom has one electron and a proton, no neutron. Therefore $\ce{H+}$ is just a proton. That is why acids are sometimes referred as ...


20

This is mostly because boric acid is commonly believed to have different acidity mechanism. While common acids generally dissociates $\ce{HNO3 <=> H+ + NO3-}$ boric acid is commonly believed to associate with water $\ce{H2O + B(OH)3 <=> H+ + [B(OH)4]-}$ this type of acidity is rather common for metal hydroxides, hence the way of writing. For ...


20

"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 of periodic tables and individual element clip art to shuttersock, iphoto, etc. in which "estrontium" is incorrectly used as the English name for strontium. The ...


19

Electrons and protons are charged particles. The electrons have negative charge, while protons have positive charge. A neutral atom is an atom where the charges of the electrons and the protons balance. Luckily, one electron has the same charge (with opposite sign) as a proton. Example: Carbon has 6 protons. The neutral Carbon atom has 6 electrons. The ...


19

Like most of the other professionals answering here, I've given a couple of talks on international conferences and published some articles in peer-reviewed journals. I have never used the terms dihydrogen monoxide or oxidane and do not intend to do so in a serious, scientific context. Typically, one talks and writes about water, aqueous solutions and even ...


19

Yes, "to the left" refers to the left side of an equilibrium expression. Traditionally, the autoionization of water is written as $$\ce{2H2O <=> H3O+ + OH-}$$ When we talk about equilibrium lying "to the left", it means that the educt/reactant is favored, i.e. more $\ce{H2O}$ than $\ce{H3O+}$ or $\ce{OH-}$. Conversely, an equilibrium that lies "to ...


19

Yes, equilibrium and steady-state are distinct concepts. A reaction is at equilibrium if reactants and products are both present, the forward and reverse rates are equal and the concentrations don't change over time. If this is the only reaction in a closed, isolated system, the entropy in the system is constant. Steady-state implies a system that is not ...


18

I liked this question because I had never thought much about it. However, it's not such a mystery because the answer is on Wikipedia's “radical” page: Historically, the term radical was also used for bound parts of the molecule, especially when they remain unchanged in reactions. These are now called functional groups. For example, methyl alcohol was ...


18

Probably you are having problems with Le Chatelier's Principle. Suppose you have an equilibrium established between four substances $\ce{A}$, $\ce{B}$, $\ce{C}$ and $\ce{D}$. What would happen if you changed the conditions by increasing the concentration of $\ce{A}$? According to Le Chatelier, the position of equilibrium will move in such a way as to ...


18

No, it's not. The "dihydrogen monoxide" name is used as part of a hoax. In the scientific community, there are chemical names for water, and which one is used in the literature generally depends on how it interacts with something else (hydroxic acid and hydrogen hydroxide were two I heard most often in acid-base reactions). IUPAC, the standards committee ...


18

It is a semantics question with an open ended discussion. If you recall the old problem "How many angels can dance on a pinhead? Medieval problem, this issue here is similar. Basically in chemistry, all the terminology is controlled or endorsed by the International Union of Pure and Applied Chemistry (IUPAC). They have a very open ended definition of a salt:...


17

I can't really provide a systematic approach, but I can attempt to clarify (as a student myself). Elements are classes of atoms. Atoms of the same element are similar (if not identical) in their physical and chemical properties (but be aware of Isotopes which are physical variations among atoms of the same element). A definite (I suppose, systematic) way to ...


17

It is essentially exactly what your teacher says: the term vitamin B complex is used because the structures assigned a name ‘vitamin Bx’ don’t really have anything in common although they are all somewhat important. As to why nobody ever uses vitamin K complex or vitamin D complex: well, at least in my country those vitamins are very under-represented when ...


17

Both answers are right. In the IUPAC Gold Book it states A liquid or solid phase containing more than one substance, when for convenience one (or more) substance, which is called the solvent, is treated differently from the other substances, which are called solutes. So either way can be used, but it is usually more conventional to call the ...


17

The reason why the generic name of most drugs have seemingly little semblance to their chemistry is in the interests of practicality; a doctor would find it easier to write sildenafil (generic name) or Viagra (brand name) in a prescription than 5-{2-Ethoxy-5-[(4-methylpiperazin-1-yl)sulfonyl]phenyl}-1-methyl-3-propyl-1$\ce{H}$,6$\ce{H}$,7$\ce{H}$-pyrazolo[4,...


16

I agree with the other answers. No serious chemist uses any word other than "water" in whatever language the chemist uses. However, the name does appear to be following the established rules for the systematic naming of binary main group covalent compounds. Take for example $\ce{N2O5}$: We list the elements in order of increasing electronegativity: ...


16

There is some disagreement in usage among authors, but IUPAC standard nomenclature approves calling beryllium an alkaline earth metal, as explained on page 51 of IUPAC's last Red Book. In fact, all the elements belonging to group 2, $\ce{Be,Mg,Ca,Sr,Ba,Ra}$, are called alkaline earth metals with IUPAC's approval. Other common traditional names approved by ...


16

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. Nope, the definitions are as follows (from the IUPAC Goldbook): cation A monoatomic or polyatomic species having one or more elementary charges of the proton. anion A monoatomic or ...


Only top voted, non community-wiki answers of a minimum length are eligible