How many unpaired electrons are in a p subshell that is filled with 4 electrons?

An atom's p orbital is able to accompany a total of 6 electrons. Remember that these electrons will be arranged in such a way as to maximize the number of unpaired electrons, according to Hund's rule. Considering that there are 3 subshells (px, py, and pz according to the Cartesian coordinate plane - don't worry, you'll learn more about this if you take college chemistry), a total of 2 electrons will occupy each subshell - totalling 6 electrons. Take into account the following example: Oxygen has a ground state electron configuratio of 1s^2; 2s^2; 2p^4. Therefore, there are 4 electrons in oxygen's 2p orbital. (Remember, a p orbital can accompany a total of 6 electrons!) Electron 1 will go into the 2px shell; electron 2 will go into the 2py shell; electron 3 will go into the 2pz shell; electron 4 will pair up with the electron in the 2px shell (therefore, there is a pair of electrons in the 2px shell). We have a total of 4 electrons in the 2p orbital, so we are done. But the 2py and 2pz shells only have 1 electron each; therefore, there are 2 unshared pairs of electrons in oxygen's 2p orbital. I hope this helps. Email me if you have any other questions. I'll be happy to help!
By: tony

Date of comment: Wed, Sep 27th 2006