In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals.

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Explanation for increase in the number of oxidation states for transition elements from Sc to Mn of the 4th period

From Sc, to Mn, the number of oxidation states increases from one (Sc) to seven (Mn). The explanation for this is because the unpaired 3d electrons can be lost along with the 4s electrons during ...
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Why is carbon tetravalent?

How does the electron from the 2s orbital "jump" to the 2p, thus leaving 4 unpaired electrons to form four covalent bonds? Also, does the octet rule not apply to carbon? If it does, how can it bond ...
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copper is more stable in+2 rather than+1 [duplicate]

Despite the fact that its electronic configuration is 3d104s1, why is copper usually found on nature in+2. Instead of more intuitive+1? I know we can explain based on enthalpies but is there a better ...
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Shells, orbitals, subshells, and energy levels

I think i Know what these mean, each row on the periodic table has a new shell of electrons, a subshell is e.g. 1s, 2s, 2p, 3s, 3p, etc and energy levels are the same as shells whilst orbitals are the ...
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Valence Shell for Transition Metals

In transition metals, is the shell with the highest energy considered the valence shell? For example, in copper the electronic configuration is ${[Ar]\text{ } 3d^{10}\text{ } 4s^{1}}$. However, in ...
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Ground State Configuration

Studying for an exam tomorrow, I came across this question. Which two ions have the same electron configuration in the ground state? A) $\ce{Rb^+}$ and $\ce{Cs^+}$ B) $\ce{Ba^2+}$ and $\ce{I^-}$ ...
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Why can Cu have an oxidation number of +2?

The electronic configuration for $\ce{Cu}$, adjusted for Hund's rule, is: $[\ce{Ar}] 3d^{10} 4s^1$ So, shouldn't $\ce{Cu}$ have an oxidation number of $+1$? whereby it gives off its outermost 4s ...
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MacGyvered chlorine gas protection

I was watching Periodic Video's chlorine video, which discusses Chlorine's ferocity in stripping electrons whenever possible, and the professors mentioned its consequent use in WWII as a chemical ...
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How are electrons in conjugated molecules excited? [duplicate]

I have recently started reading about colour in organic molecules and come across conjugation of pi bonds. My question is pretty short... In transition metal ions I understand colour is caused by ...
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What is the appropriate procedure for determining the quantum numbers of an electron?

How do I find the set of quantum numbers for a specific electron in an element? For example, Calculate the set of quantum numbers for the 19th electron in chromium. The electronic configuration ...
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Why is the 8-electron rule more important than the 2- or 18-electron rule

Why is the fulfilled electronic configuration of only $p$ orbital is stable. I mean why $II-B $ group with fulfilled $d$ orbital,$II-A$ group with fulfilled $s$ orbital...are not stable. Why makes ...
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Could someone please explain the difference between m/z and m/e in mass spectroscopy

The definition: The abbreviation m/z is used to denote the dimensionless quantity formed by dividing the mass number of an ion by its charge number. It has long been called the mass-to-charge ratio ...
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Bonding, multiplicity and quantum chemistry for FeP$_2$

I'm trying to do some quantum chemical calculations for the linear molecule FeP$_2$ in the gas phase as well as its crystal (orthorhombic symmetry like here). I am lead to believe that in both cases ...
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How to determine mineral properties based on chemical formula?

I need to learn a bunch of minerals and their properties. What I want is some sort of rule which helps me deduce color, crystal system, luster etc. I know that different kind of ions give specific ...
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Is there an energy cost associated with flipping the spin of an electron?

THE STORY: A common example used to illustrate the limitations of restricted Hartree-Fock (RHF) theory is the H$_2$ dissociation energy ($D_e$) curves. RHF enforces electrons to be paired into spin ...
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A reversible exothermic reaction between a molecule in an excited triplet state and a reducing agent

Say I promote a molecule to a triplet state via repeated electronic excitation events. Here, this is going to mean that an electron from the HOMO level, originally with a spin-UP and spin-DOWN ...
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What does the subscript of atomic orbital mean?

As everyone knows, the atomic orbital can be classified as $s, p_z, p_x, p_y, d_{z^2},d_{xz},d_{yz},d_{xy},d_{x^2-y^2}$ and so on. I want to know the meaning of $z^2,x^2-y^2$ and so on. Maybe this is ...
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If two electrons move up to a higher energy level in an atom, is it considered excited?

In Germanium, if two electrons go from 1s go to 4p is it in its excited state?
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Why is the orbital angular momentum of a pi electron along the axis of two atoms' molecule one?

I'm reading quantum chemistry. The book says that the orbital angular momentum of a $\pi$ electron along the symmetry axis of a molecule made up of two atoms is $\pm 1$. I think this is a primary ...
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Classifying atoms as metals or nonmetals based on the periodic table [closed]

The electron configuration of the outer shell of four atoms are: $X: 3s^23p^3, Y: 6s^26p^3, Z: 3s^23p^4 T: 6s^26p^4$. I don't know if these atoms are metal or nonmetal. Please classify the four ...
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Ground state electron configuration of chromium

What is the ground state electron configuration of chromium? Is it [Ar]4s23d4 or Is it [Ar]4s13d5
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lanthanide contraction

"The Lanthanide Contraction refers to the fact that the 5s and 5p orbitals penetrate the 4f sub-shell so the 4f orbital is not shielded from the increasing nuclear change." First, 5s and 5p are ...
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Why does $\text{Cr}^{3+}$ not have the same electron configuration as $\text{Sc}$?

To be explicit, $\text{Cr}^{3+}$ and $\text{Sc}$ have the same number of electrons, the only difference is the nuclear charge. This is not an isolated anomaly, it seems: the book I'm using claim ...
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The energy gap between a pi-conjugated system with (2 bonding and 1 anti-bonding orbital) and (1 bonding and 2 anti-bonding) orbitals

I asked a question previously about "why" it is the case the expanding the size of pi-conjugated systems decreases the required energy to excite an electron from a HOMO to a LUMO band: Why does the ...
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Does the emission spectrum for a dye depend on the frequency of light used to excite the dye?

Take a look at the emission spectrum for an arbitrary fluorescent dye: http://en.wikipedia.org/wiki/File:Fluorescein_spectra.jpg Does the emission spectrum depend on exciting the dye at its peak ...
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Why does the energy gap for π - π* transitions shrink with the size of the pi-conjugated system?

Quoting from this site: As conjugated pi systems become larger, the energy gap for a π - π* transition becomes increasingly narrow, and the wavelength of light absorbed correspondingly becomes ...
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maximum number of electrons each shell

In my textbook it says that the maximum number of electrons that can fit in any given shell is given by 2n². Which would mean 2 electrons could fit in the first shell, 8 could fit in the second shell, ...
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Why does the 3rd electron shell start filling up with scandium?

The electron configuration of calcium is 2, 8, 8, 2, where up to that point each shell, asides from the first shell counts up to 8 - why then does scandium have an electron configuration of 2, 8, 9, ...
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Where does the 9th electron go in a $\ce{N=O}$ bond?

In the first resonating structure you can see 5 unpaired electrons and 4 shared electrons on nitrogen, then isn't this a extended octet? If it is so, then in which orbital that 9th electron is ...
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Electron Configuration of Tellurium

Below is a copy of the method I am using to determine electron configurations. I started doing some practice questions (unfortunately there were no answer keys attached to it -- so I consulted ...
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What is an intuitive explanation for Electron Configurations

I'm sort of self studying Chemistry. I'm now getting stuck wrapping my head around a concept (and I realize it was the same concept I had difficulty grasping years ago) and that is Electron ...
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Configuration Interaction matrix composition from electronic configurations

The six electronic configurations below could all be found in the matrix elements of the CI matrix at CISD level. How do I construct the 6 x 6 CI matrix composed of these six configurations and which ...
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Explaining the oxidation states of palladium

Palladium follows an exception to normal electron filling-up rules and so has the electron configuration of $\ce{[Kr] 4d^{10} 5s^0}$ The oxidation states of palladium are $\ce{+II}$ and $\ce{+IV}$. ...
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Plutonium having more oxidation states than samarium?

Why does plutonium have more oxidation states than samarium? Electron configuration of Pu: $\ce{[Rn] 5f^6 7s^2}$ Electron configuration of Sm: $\ce{[Xe] 4f^6 6s^2}$ I thought that only the valence ...
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Comparision in ionization enthalpy of Cs and Fr

Why ionization enthalpy of Fr is greater than Cs even though it have larger size. I found no google result regarding.
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Why does ammonia have sp hybridization?

Apparently it has sp3 hybridization, but I don't understand why. Ammonia (NH3) seems to me to not require sp hybridization because all of its bond lengths are already equal. It has 3 hydrogens bonded ...
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Does the hybridization model gives us any further insight on Molecular Geometry?

It doesn't seem as though the hybridization model adds anything useful to the discussion of molecular geometry as predicted by the VSEPR model. It's just another way of labeling linear, trigonal ...
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How to compute the electron configuration of an atom?

How to compute the electron configuration of an (electrically neutral) atom ? So when given the atom number how does one compute the electron configuration ? I know the sum of electrons must equal ...
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what is a difference between outer electrons and unpaired electrons

I know outer electrons include (n-1)d...+ all n'ss.. But i don't understand, never been told what unpaired electron is supposed to be? is it the same thing. so in the following electron ...
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Memorize Transition Metal Electronic Ground State

In the course of my undergraduate studies it has become clearer and clearer that it is quite helpful to know the ground electronic state of transition metals by heart, if only to speed up the process ...
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Have there been no advances in the determination of effective nuclear charges since Clementi and Raimondi in the 60s?

Effective nuclear charge is a very important concept in chemistry, and is the basis for the qualitative explanation of many observed chemical and physical properties, including several periodic ...
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What is the electron configuration of Br-?

It's easy to do atomic electron configuration, but ionic is confusing.
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Is ionic bond just formed by “electrostatic” interaction between two oppositely charged ions?

According to the definition of ionic bond: An ionic bond is a type of chemical bond formed through an electrostatic attraction between two oppositely charged ions. If we consider the above ...
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Difference between inorganic and organic semiconductors: electronic structure or configuration, or?

Organic semiconductors differ from inorganic semiconductors. In organic semiconductors the molecules are held together by weak van der Waals interactions and in inorganic semiconductors by covalent ...
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Is the electron configuration redundant?

For example the electron configuration for oxygen is 1s2 2s2 2p4. But if an element can never have an element in the p orbital unless it has 2 full s orbitals*, then why can't we write 2p4 as the ...
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The Violation Of A Certain Rule or Principle in the following Electronic Configuration

I've to detect the violation of a certain rule or principle in the following electronic configuration: $1s^2,2s^2,2p^1_x,2p^0_y,2p^0_z$ 1) If we test this configuration for $n+l$ rule, then we come ...
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Number of $\pi$-electrons in an energy state

I am learning quantum chemistry and I am trying to understand the statement in a .pdf I'm reading which states "The energy transition associated with the spectral transitions observed is: $$\Delta E = ...
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Lone pair electrons on secondary carbon vs primary carbon

I know that a molecule is more stable when a free radical is on a secondary carbon over a primary carbon, but how about when there is a lone pair of elections that can be placed on a secondary or ...
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Why apart from when building atoms in the first place, the 3d is the lower energy orbital?

"If the phosphorus is going to form PCl5 it has first to generate 5 unpaired electrons. It does this by promoting one of the electrons in the 3s orbital to the next available higher energy orbital. ...