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Topic: Atom structure  (Read 2985 times)

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Offline kapital

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Atom structure
« on: August 25, 2009, 05:06:28 PM »
What is the diffrence between orbital, shell and subshell? I assume that nothing of this exist, it is all just theoretical place of electrons. If orbital is a place when the electron is found in 95% probability, what are then shells and subsels? And when vhen we write and electronic configuration, example 1s2 2s2 2p3, numers mean shells, and the letters mean orbitals. Why we dont write down the subshells to? I hope the question is not to much non specific. Thanx for answers.

Offline renge ishyo

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Re: Atom structure
« Reply #1 on: August 25, 2009, 08:16:24 PM »
Hi there kapital,

The different names are for grouping purposes. Here is a breakdown of the three groups:

Orbital - Each orbital can only hold a maximum of two electrons. For example, the 2s orbital can hold a maximum of two electrons.

Shell - Includes all the orbitals that are in a row on the periodic table. For example, the 2s orbital and all three 2p orbitals together form a shell (since these are all the orbitals that appear in row number 2).

Subshell - Includes all the orbitals in a row that have the same orbital type. For example, the three 2p orbitals together form a subshell. This subshell does not include the 2s orbital because an s orbital and a p orbital are not of the same type.

Hope this helps.

Offline Yggdrasil

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Re: Atom structure
« Reply #2 on: August 26, 2009, 02:19:14 AM »
Why we dont write down the subshells to? I hope the question is not to much non specific. Thanx for answers.

This is a good question, and the answer has to do with energy.  First, to clarify nomenclature, we'll refer to the four quantum numbers: the principle quantum number (aka energy level, 1, 2, 3, etc.), the azimuthal quantum number (s, p, d, f, etc.), the magnetic quantum number (e.g. which specific type of orbital such as px, py and pz), and the spin quantum number (+1/2 or -1/2).  The energy of an orbital depends on the principle quantum number and (for all atoms except atoms with only one electron) the azimuthal quantum number.  In most cases, the magnetic quantum number and spin quantum number have no effect on the energy of the orbital (there are, howerver, special cases, where states with different magnetic or spin quantum numbers have different energies--for example, the presence of an external magnetic field).

Because states with different azimuthal quantum number have the same energy, the order in which the orbitals are filled does not matter.   So, for an atom like boron (electron configuration 1s2 2s2 2p1), the highest energy electron could have gone into either the px, py or pz orbital because they all have equal energy.  Since we don't know which orbital the electron went into, we cannot provide the information in the electron configuration.

Offline kapital

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Re: Atom structure
« Reply #3 on: August 26, 2009, 06:08:51 PM »
I understend this more, but have some similar ptoblems again.I have got a problems with imaginating all this. For example where inside of the shell orbitals are? I draw a picture to explain how my thinking. I draw orbitals somewhere randomly in shells. But thats probably not how it and now i am asking how it is? I draw an two dimensional atom

Offline UG

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Re: Atom structure
« Reply #4 on: August 27, 2009, 02:01:16 AM »
I quite like this diagram.

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