Electron Arrangement in an Atom

1. Electron Arrangement in an Atom

2. Electron Configuration • The ways in which electrons are arranged into various orbitals around the nuclei of atoms. • To find electron configuration we rely on three rules: • The aufbau principle • The Pauli exclusion principle • Hund’s Rule

3. Aufbau Principle • Electrons occupy the orbitals of lowest energy first. • The range of energy levels of a principle level can sometimes overlap the energy levels of another principle level (Look below)

4. Pauli’s Exclusion Principle • An atomic orbital may describe at most two electrons . • One or two electrons can occupy an orbital of any sublevel. • If two occupy the same orbital, they must have opposite spins

5. Hund’s Rule • Electrons occupy orbitals of the same energy in a way that makes the number of electrons with the same spin as large as possible. • After, a second electron enters the orbitals so that each is paired with opposite spins

6. Electron Configuration • If I tell you that the exponents are the number of electrons, what elements have the following electron configurations: 1.) 1s22s22p1 2.) 1s22s1 3.) 1s22s22p63s2 1.) Boron (B) 2.) Lithium (Li) 3.) Magnesium (Mg)

7. What is the electron configuration of the following elements? 1.) Hydrogen 2.) Ne 3.) Potassium 1.) 1s1 2.) 1s22s22p6 3.) 1s22s22p63s23p64s1 Now use those electron configurations to fill an orbital diagram with electron spins

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