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Orbital Diagrams. And Electron Configurations. Electrons behave as though they are spinning on their axis. A half arrow is used to indicate if the direction of the spin is up ( ) or down ( ). Electron configuration. H: 1 electron. , 1s 1. Pauli Exclusion Principle:
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Orbital Diagrams And Electron Configurations
Electrons behave as though they are spinning on their axis. A half arrow is used to indicate if the direction of the spin is up ( ) or down ( ). Electron configuration H: 1 electron , 1s1
Pauli Exclusion Principle: Each orbital can contain 2 electrons ONLY if the electron spins are in opposite directions. He: 2 electrons , 1s2
Auf bau principle: the electrons fill the orbitals starting with the lowest energy level and working their way up the energy ‘ladder’ Li: 3 electrons , 1s2 2s1
Be: 4 electrons , 1s2 2s2
B: 5 electrons , 1s2 2s2 2p1
Hund’s Rule: all sublevel orbitals of the same energy must be filled with a single electron before the electrons can begin to pair up. C: 6 electrons , 1s2 2s2 2p2
Total electrons 10 12 18 20 21 2 4 complete configuration Sc: 21 electrons , 1s2 2s2 2p6 3s2 3p6 4s2 3d1 Shorthand notation: [Ar] 4s2 3d1 noble gas core configuration
Rules to Drawing Electron Dot Structures • Electrons 1-4 are added singly. • Exception: If there only two electrons, they’re shown as a pair. • Electrons 5-8 are paired with the single electrons that are already there. Electron Dot Structures Chemical reactivity depends upon the number of electrons in the highest energy level (the largest n). • Electron dot structures show only the outermost electrons so that reactivity can be easily predicted. • The outermost electrons are also called the valence electrons.
Examples: 1. What is the electron configuration of strontium (Sr)? 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 The highest energy level is n=5 and there are 2 electrons in it. Therefore, Sr has 2 valence electrons. Sr 2. What is the electron configuration of nitrogen (N)? 1s2 2s2 2p3 N The highest energy level is n=2 and there are 5 electrons in it. Therefore, N has 5 valence electrons. 3. What is the electron configuration of xenon (Xe)? 1s2 2s2 2p6 3s2 3p6 4s2 3d10 3p6 5s2 4d10 5p6 The highest energy level is n=5 and there are 8 electrons in it. Therefore, Xe has 8 valence electrons. Xe