Rules for Assigning Electron Orbitals
Occupation of Orbitals
Electrons fill orbitals in a way to minimize the energy of the atom. Therefore, the electrons in an atom fill the principal energy levels in order of increasing energy (the electrons are getting farther from the nucleus). The order of levels filled looks like this:
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, and 7p
One way to remember this pattern, probably the easiest, is to refer to the periodic table and remember where each orbital block falls to logically deduce this pattern. Another way is to make a table like the one below and use vertical lines to determine which subshells correspond with each other.
Example
Following the pattern across a period from B (Z=5) to Ne (Z=10), the number of electrons increases and the subshells are filled. This example focuses on the p subshell, which fills from boron to neon.
Outside links
Occupation of Orbitals
Electrons fill orbitals in a way to minimize the energy of the atom. Therefore, the electrons in an atom fill the principal energy levels in order of increasing energy (the electrons are getting farther from the nucleus). The order of levels filled looks like this:
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, and 7p
One way to remember this pattern, probably the easiest, is to refer to the periodic table and remember where each orbital block falls to logically deduce this pattern. Another way is to make a table like the one below and use vertical lines to determine which subshells correspond with each other.
Example
Following the pattern across a period from B (Z=5) to Ne (Z=10), the number of electrons increases and the subshells are filled. This example focuses on the p subshell, which fills from boron to neon.
- B (Z=5) configuration: 1s2 2s2 2p1
- C (Z=6) configuration:1s2 2s2 2p2
- N (Z=7) configuration:1s2 2s2 2p3
- O (Z=8) configuration:1s2 2s2 2p4
- F (Z=9) configuration:1s2 2s2 2p5
- Ne (Z=10) configuration:1s2 2s2 2p
Outside links
- CHEMTUTOR has a section on the atomic structure that may be useful in reviewing a few fundamental concepts about elements . The page topics transition into electron configurations and the octet rule (useful in later sections) http://chemtutor.com/struct.htm
- Wikipedia also has a section on the electron configurations, but goes into slightly more detail about topics not covered here such as exceptions, ionization, Madelung's rule, and applications of electron configurations.
- http://en.wikipedia.org/wiki/Electron_configurations
- http://www.youtube.com/watch?v=FmQoSenbtnU&feature=youtube_gdata
- http://www.youtube.com/watch?v=RJlEH5Jz80w&feature=youtube_gdata
- http://www.youtube.com/watch?v=YURReI6OJsg&feature=youtube_gdata
- http://www.youtube.com/watch?v=1TZA171yxY4&feature=youtube_gdata