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143 votes
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Why doesn't H₄O²⁺ exist?

I myself was always confused why $\ce{H3O^+}$ is so well-known and yet almost nobody talks of $\ce{H4O^2+}$. I mean, $\ce{H3O^+}$ still has a lone pair, right? Why can't another proton just latch onto ...
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37 votes
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Why does salt dissolved in water taste like salt? If it's just Na+ and Cl- ions

When you taste salt, you're not pushing crystalline $\ce{NaCl}$ into your taste buds. It dissolves in your saliva and dissociates. When one tastes salt, the saltiness taste receptors respond ...
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34 votes
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Do atoms form either a positive or a negative charge, but not both?

Actually, in theory almost all of the elements can be found with both positive and negative oxidation numbers: it's just a matter of finding a system with the proper reagents and conditions to force ...
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32 votes
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Does the term 'Cation' always refer to a positively charged particle?

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 ...
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29 votes

Bonding in the phosphate ion

First of all, let me state the obvious: Phosphorus is awesome. After we got that out of the way we can focus on why. There are many different modifications of phosphorus in nature. With increasing ...
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26 votes
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Can metals have a net negative charge

These species usually do not exist in nature, but they can be synthesized. Silver has been reduced in liquid ammonia to give $\ce{Ag-}$. A lot of anionic metal carbonyl complexes $\ce{M(CO)_{n}^{m-}}$...
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24 votes
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How should the hydrated proton be represented in chemical equations?

In addition to entropid's answer, let's remember why we invoke the hydronium ion $\ce{H3O+}$ in the first place. We use $\ce{H3O+}$ as a shorthand for $\ce{H+(aq)}$, which looks more like protonated ...
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23 votes

What is difference between H⁺ and proton?

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 ...
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  • 7,046
23 votes

Do non-classical carbanions exist?

Interesting question. It is much less studied and reported on than the case of non-classical carbocations, but I did find a few papers. Brown and Occolowitz (Ref.1) reported that deuterated bicyclo[3....
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22 votes

How was it concluded that the H3O+ rather than H+ is the "acid" ion?

Actually, the initial theories before Lewis suggested that $\ce{H+}$ is the cause of acidity. However, it soon turned up that an ion as small as the nucleus of hydrogen (you may simply call it a ...
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21 votes
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Why are protons more common than hydride ion?

This is because we live in a world dominated by oxygen and water. In other words, it is an oxidized world. Most metals occur naturally in the form of oxides, silicates, halides, or other derivatives. ...
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19 votes

Do ligands with a positive charge exist?

Aromatic cations like the tropylium cation ($\ce{C7H7+}$)[1] or the cyclopropenyl cation ($\ce{C3H3+}$)[2] can coordinate to metals, creating sandwich or half-sandwich compounds. The positive charge ...
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18 votes
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Do non-classical carbanions exist?

In addition to the species mentioned in the answer above, I found another one in Organic Chemistry by Morrison and Boyd(Seventh Edition)
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17 votes
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Can H4O 2+ form?

The existence of $\ce{H4O^{2+}}$ has been inferred from hydrogen/deuterium isotopic exchange monitored through $\ce{^{17}O}$ NMR spectroscopy in the most extremely acidic condensed phase superacid we ...
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17 votes

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. Nope, the definitions are as follows (from ...
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17 votes

Can glass be deionized?

You can indeed "harden" glass by exchanging ions on the surface, but not because it turns into quartz glass. Quartz glass is mostly so robust because it has an extremely small thermal expansion ...
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16 votes

Do ligands with a positive charge exist?

The nitroso ligand ($\ce{NO^+}$) is also one of the most commonly occurring positively charged ligands.
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16 votes
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Negative ions and health: pseudo science or something more?

Charge separation at waterfalls with airborne ions, resulting in a potential between the base of the waterfall and the surrounding air, is a phenomenon examined by Philipp Lenard (Über die ...
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16 votes

Differentiation between zinc, aluminium, and magnesium ions in solution

Apart from the methods, Ringo already described, you can do a few other tests. Aluminium This is loosely translated from the German chemgapedia.de. Look at the pretty pictures. Probably the easiest ...
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16 votes

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

Short version: We don't call bonds "physical", there are chemical bonds and other types of interactions between particles. The chemical bonds are classified this way because they make up molecules, ...
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16 votes
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Does the hydrogen ion actually exist?

Yes free $\ce{H+}$ ions, protons, really exist. Protons are constantly emanating from the sun and reaching Earth. The proton flux is continuously monitored by satellite. However, in a ...
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  • 38.8k
16 votes

Why doesn't H₄O²⁺ exist?

In chemistry ask "why" only after you ask "if". Given a sufficiently strong superacidic medium, $\ce{H3O^+}$ can be protonated to $\ce{H4O^{2+}}$. Evidence for this reaction, by ...
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15 votes
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Why are bromine oxyanions uncommon?

I can only really speak for bromine(VII). Bromine(V) is pretty common and I'm not entirely sure what's the deal with Br(I) readily disproportionating to Br(V) + Br(-1). (The tendency of Br(I) to ...
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15 votes
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Superscript and subscript together after the same atom

From IUPAC Green Book [1, p. 51]: In writing the formula for a complex ion, spacing for charge number can be added (staggered arrangement), as well as parentheses: $\ce{SO4^2-}$, $\ce{(SO4)^2-}$. The ...
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14 votes
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Flame test: Is the metal atom or the metal ion responsible for the flame colour?

The phenomenon that is witnessed during a flame test is an "atomic emission". This statement may seem inappropriate, since it is a solution of metal ions (and not atoms) that is tested. The reason for ...
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14 votes
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Why the salts in a salt bridge?

The purpose of the salt bridge is to prevent the two half-cell solutions from mixing. It is possible to make a really bad galvanic cell by putting both half-cells in a single solution, but they ...
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14 votes
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Why Ca 2+ and not Ca +2

Chemistry has an organization called the International Union of Pure and Applied Chemistry (IUPAC), which sets standards for nomenclature (among other things). Chemists usually follow its ...
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14 votes
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Why are hydrogen ions always associated with another molecule?

The way I understand it is (and my understanding is by no means perfect, or complete), as you pointed out correctly: a hydrogen ion is in fact a proton. The proton is a "bare charge" and as you ...
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14 votes
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Can you in reality give neon a charge of +8?

Of course you can take all the electrons off an atom - it is then called "fully stripped" in atomic physics. You don't need to do it to an entire mole, mind you. In accelerators one would send ...
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  • 7,591
13 votes

Is the atom the smallest particle, which takes part in chemical reactions?

Protons definitely participate in chemical reactions. Free protons are generally not present in liquid water because a free proton is extremely reactive, but in the upper atmosphere or in other ...
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