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Topic: I need help with electron configuration  (Read 8785 times)

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babyliseca

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I need help with electron configuration
« on: June 14, 2004, 11:40:53 PM »
Hey everyone, can anyone please help me with a question I'm stuck on?  I'm having a hard time understanding this particular topic.

I'm having problems understanding electron configuration.  Is there anyone that can explain it a lil clearer then the text for me?  I need to write 6 ions that have the same electron configuration as Ne (neon).  Can anyone help me with one or two to start?  Thanks!


Offline AWK

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Re:I need help with electron configuration
« Reply #1 on: June 15, 2004, 06:25:44 AM »
N3-, O2-, F-, Na+, Mg2+, Al3+
AWK

babyliseca

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Re:I need help with electron configuration
« Reply #2 on: June 15, 2004, 10:03:16 AM »
Thanks AWK!  Appreciate it alot  :)  Can anyone else try and explain electron configuration in layman's terms for me?

chemicalLindsay

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Re:I need help with electron configuration
« Reply #3 on: June 16, 2004, 04:37:43 AM »
I dont know if i am boring you on stuff you allready know but the maximum amount of electrons in a shell of an atom is 2n squared when n stands for the shell number.Know electron configureation from my recollection is basically the configuration or in easier terms the placement of electrons in different shells or energy levels around the nucleus of an atom and the valence shell (outermost shell) will allways generally contain the same number of electrons as its group number .so for example flourine used in the previous example is in group 7 ,thus has 7 valence electrons and 2 other electrons in the inner most shell which is full .there is a picture atttached of flourines general electron configuration and this should help you to understand it a bit better.

Offline Donaldson Tan

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Re:I need help with electron configuration
« Reply #4 on: June 18, 2004, 04:00:33 AM »
I try to explain electronic configuration as simple as possible..

electronic configuration would tell us the composition of energy levels of the electrons inside the atom/ion.

An electron shell can hold up to 2n^2 number of electrons (where n is the shell number). Application of this equation would tell you that the first shell holds a max of 2e, and max of 8e for the 2nd shell.

Using the above idea, the electronic configuration of oxygen (proton number 8) is 2.6. It means the first shell contains 2e and 2nd shell contains 6e. Consequently, oxygen is in group 6. Elements in the same group contain the same number of valence electrons. Valence electrons are the electrons in the outermost electron shell.

Next, we are going to split the electron shell into sub-shells, namely the s, p, d & f (in order of increasing energy level). The number of sub shell would correspond to the shell number. Eg. the first shell would only contain 1 sub-shell, ie. 1s. The 2nd shell would contain 2 sub-shells, ie. 2s and 2p. The 3rd sub-shell would contain 3s, 3p and 3d. An interesting feature to note is that 3d energy level is lower than that 4s. This results in the interesting properties in the transition metals (the column of elements between group 2 and 3 in e periodic table).

The sub-shell energy levels are ranked in this order:
1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p .. (this is less than complete. refer to a general chemistry textbook for the full order)

Each sub-shell would contain a specific number of orbitals. Each orbital can hold up to max of 2e (with reference to Pauli's Exclusion Principle). s subshell contains 1 orbital, p subshell contains 3 orbitals, d subshell contains 5 orbitals, f subshell contains 7 orbitals. I hope u can see the pattern, that 1,3,5,7 are actually increasing odd numbers with reference to increasing energy level of s,p,d to f.

Electrons are filled into their subshell according to Aufbau's Princple, that lower energy level is being filled first. Also note that electrons are filled to minimise inter-orbital electronic repulsion too.
Eg. if I were to have 4 electrons to fill the 3 2p-orbitals, I would end up with 1 full orbital and 2 half-filled orbitals, and not 2 full orbitals. Imagine that if u have two electrons in the same orbital (aka same confinement into 3D space), their electronic repulsion would be maximised, because they are so near to each other. Electronic configuration are such that the atoms/ions would be at the lowest energy level at their ground state.

Now, back to the example of Oxygen (2.6), the electronic configuration can be re-written as 1s2 2s2 2p4. 1s2 would mean there are 2 electrons in the s energy level of the first shell. 2s2 would mean there are 2 electrons in the s energy level of the 2nd shell. 2p4 would mean there are 4 electrons in the p energy level of the 2nd shell. Notice that when u sum the number of electrons in the same shell, they correspond to first form of electronic configuration (2.6)

I hope reading this will increase your understanding on electronic configuration.

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