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There's another question related to salt bridges on this site. The purpose of a salt bridge is not to move electrons from the electrolyte, rather it's to maintain charge balance because the electrons are moving from one-half cell to the other. The electrons flow from the anode to the cathode. The oxidation reaction that occurs at the anode generates ...


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Something worth adding to this discussion that I'm surprised hasn't been mentioned about such "hypervalent" molecules like $\ce{SF6}$. One of my professors at university informed me that the common explanation (that the empty d-orbitals are empty and are thus accessible) is actually most likely incorrect. This is an old-model explanation that is out-of-date,...


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Shells and orbitals are not the same. In terms of quantum numbers, electrons in different shells will have different values of principal quantum number n. To answer your question... In the first shell (n=1), we have: The 1s orbital In the second shell (n=2), we have: The 2s orbital The 2p orbitals In the third shell (n=3), we have: The 3s orbital The ...


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Here's a graphic I use to explain the difference in my general chemistry courses: All electrons that have the same value for $n$ (the principle quantum number) are in the same shell Within a shell (same $n$), all electrons that share the same $l$ (the angular momentum quantum number, or orbital shape) are in the same sub-shell When electrons share the same $...


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There is a big difference between a "rule" and a law of nature. The "octet rule" is a turn-of-the-last-century concept that somehow managed to get into introductory chemistry books and never got kicked out with the advent of modern quantum mechanics. (Circumstantial proof: it is impossible to identify individual electrons to label them "valence" or "not ...


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The pattern of maximum possible electrons = $2n^2$ is correct. Also, note that Brian's answer is good and takes a different approach. Have you learned about quantum numbers yet? If not... Each shell (or energy level) has some number of subshells, which describe the types of atomic orbitals available to electrons in that subshell. For example, the $s$ ...


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You seem to be misunderstanding what is a "sea of electrons". In fact, this is a metaphor upon a metaphor upon an abstraction. There is no sea. There is a huge bunch of orbitals. (Sure, the solid state people prefer to call them "states", but that's not really important.) The whole piece of metal is a giant molecule. It is not all that different from ...


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Disclaimer My following answer is the "traditional" explanation of Hund's first rule, which is based on a smaller value of $V_\mathrm{ee}$ (electron-electron repulsions) in the triplet state arising from Fermi holes. According to Levine's Quantum Chemistry 7th ed.: This traditional explanation turns out to be wrong in most cases. It is true that the ...


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The analogy with a proton is actually a good one if you are careful to remember that an electron is nearly 2000 times lighter than a proton. What does that mean? It means that despite the fact that an electron is very "small", the electron is actually going to be very large because lighter particles will tend to spread out and have a much more diffuse ...


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Fluorine is the most electronegative element because the definition of electronegativity makes it so. The electronengativity scales are defined based on experimentally determined properties of the elements. Fluorine has appropriate values for all of the common scales to ensure it has the highest electronegativity. The Pauling scale, which is the first ...


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s, p, d, f and so on are the names given to the orbitals that hold the electrons in atoms. These orbitals have different shapes (e.g. electron density distributions in space) and energies (e.g. 1s is lower energy than 2s which is lower energy than 3s; 2s is lower energy than 2p). (image source) So for example, a hydrogen atom with one electron would be ...


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It depends on what you mean by "spin". If you mean "have intrinsic internal angular momentum, independent of its trajectory through space", then yes, electrons spin, and that's what the quantum number is measuring. Though if by "spin" you mean "undergoes rotation" ("there's a little billiard ball, and if I were to put a mark on it and watch it, the mark ...


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There are 3 types of octet rule "violations" or exceptions molecules with an odd number of electrons, such as nitric oxide (image source) molecules with less than 8 electrons around an atom, $\ce{BeCl2}$ and $\ce{BH3}$ serve as examples (image source) molecules with more than 8 electrons around an atom, such as $\ce{PCl5}$ or $\ce{SF6}$ Take a look at ...


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Short Answer: No. Long Answer: First, strictly speaking, the orbitals themselves in the quantum mechanical sense are not probability distributions. They are eigenfunctions $\Psi_i$ of the Hamiltonian as defined by the time-independent Schroedinger equation $H\Psi_i=E_i\Psi_i$. The probability distribution function $p(\vec r)$ for electrons is generated ...


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Quoting from the Nobel lecture of Hans G. Dehmelt (1989): With the rise of Dirac’s theory of the electron in the late twenties their size shrunk to mathematically zero. Everybody “knew” then that electron and proton were indivisible Dirac point particles with radius R = 0 and gyromagnetic ratio g = 2.00. The first hint of cuttability or at least ...


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The lowest energy state has parallel spins to maximize the exchange energy. As you say, there's a Coulomb repulsion between two electrons to put them in the same orbital. There's also a quantum mechanical effect. The exchange energy (which is favorable) increases with the number of possible exchanges between electrons with the same spin and energy. Going ...


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I'll try an answer to this question because I watched this video a while back and did a bit of reading on it at the time and I think I understand the big picture. The problem is that these solvated electrons are very complicated things, and do not lend themselves to the traditional ways that chemists would like to think about things. For that reason, there ...


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Atoms are composed of a positively charged nucleus and an outer shell of negatively charged electrons. When two atoms come into close proximity, their electron shells repel, preventing the atoms from sharing the same space. The "volume" of an object can generally be understood as the total measure of space that is unavailable for other objects to occupy, as ...


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The ratio of the speed of an electron traveling in the first Bohr orbit to the speed of light is given by the handy equation $$\mathrm{V_{rel}=\frac{[Z]}{[137]}}$$ where Z is the atomic number of the element under consideration and 137 is the speed of light in atomic units, also known as the fine structure constant. Consequently a 1s electron in the ...


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If I understand the question correctly, OP is somewhat surprised that Coulomb's law is used to describe the interaction between an electron and a nucleus, although it is usually pictured that electrons are moving and Coulomb's law describes interaction between static particles. Should not then the Lorentz law be used instead Coulomb's one? First note, that ...


15

This is an example of terminology which should be taken with a grain of salt. The term "effective nuclear charge" is often casually symbolized with $Z_\mathrm{eff}.$ This is a universally accepted simplification, but you should keep in mind that the effective nuclear charge is, strictly speaking, $Z_\mathrm{eff}e,$ where $e$ is the elementary ...


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Without the salt bridge, the solution in the anode compartment would become positively charged and the solution in the cathode compartment would become negatively charged, because of the charge imbalance, the electrode reaction would quickly come to a halt. It helps to maintain the flow of electrons from the oxidation half-cell to a reduction half cell, ...


14

Great Question. From this article, it seems that extreme conditions of pressure can lead to new type of molecules,bondings and how the electrons participate in the bonding. Under very high pressures, it appears, electrons in the atom's inner shells can also take part in chemical bonds. “It breaks our doctrine that the inner-shell electrons never ...


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So, from Wikipedia article on VSEPR theory we read: The overall geometry is further refined by distinguishing between bonding and nonbonding electron pairs. The bonding electron pair shared in a sigma bond with an adjacent atom lies further from the central atom than a nonbonding (lone) pair of that atom, which is held close to its positively ...


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Usually when adding electrons based on the Aufbau principle, you go from one element to the next highest one, e.g. from $\ce{Ti}: \ce{[Ar] 4s^2 3d^2}$ to $\ce{V: [Ar] 4s^2 3d^3}$. Thus you add not only an electron but also a proton to your atom. When you remove electrons to get to a cation, you only remove electrons. Thus it is a different situation, with ...


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This is a very fundamental question and for really understanding the "why" some advanced physics is involved. I will describe the process rather superficially. As you might know, the level energies of atoms and molecules can be calculated (in principle) using quantum mechanics. The simplest system is the hydrogen atom as it consists of a single ...


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Now that's a mildly non-trivial observation. Why would they be equal, really? Let's say a particle with mass $m$, charge $q$, and initial velocity $v$ enters an area of length $L$ where an electric field $E$ starts to deflect it sideways. This is a clear example of uniformly accelerated motion, and its laws are well known: $x=vt,\;y={at^2\over2}$, where the ...


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The normal case for a covalent bond is indeed a 2-centre 2-electron bond. There are however cases, where 3 centres (= atoms) either share 2 or 4 electrons. In organic chemistry, the most famous case for an electron-deficient 3-centre 2-electron bond is the 2-norbornyl cation. In inorganic chemistry, boranes with their banana bonds are the role models. ...


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You have to think about the whole process. When a metal loses electrons to make a metal ion the following happens: The metallic bonds holding the metal atoms together are broken. The metal atom loses the electrons. The resulting metal ion is hydrated. In your analysis you are only focusing on step 2. The enthalpy and entropy of the entire process factor ...


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Because it takes two to tango. Dipoles interact with each other. A Lone dipole has nothing to interact with (other than an electric field, but if we ignore some externally applied macro field, there is nothing for a lone dipole to interact with). So molecules with an inherent dipole (like water or chloroform) interact with each other. One molecule's dipole ...


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