Electron configuration
- 1. Electron configuration D.M K.M S.H Z.M I.S
- 2. Contents Introduction: Learning Objectives Arrangement of electrons in an atom 2 Atomic orbitals Electron configuration Filling rules for electron orbitals Energy levels and sublevels Examples and questions
- 3. Introduction: Learning Objectives 1. Describe the structure of energy levels 2. Define s, p and d orbitals, and describe their shapes 3. Describe the rules for assigning electrons to subshells 4. Deduce the electron configuration of an atom from its atomic number 5. Compare electron configurations of atom and ion
- 4. Electrons exist in layers called shells. (The shells can also be called energy levels). The arrangement of electrons in these shells is often called the electron configuration. 1st shell 2nd shell 3rd shell Arrangement of electrons in an atom
- 5. Each energy level has a maximum number of electrons that it can hold. Electrons will fill the level nearest the nucleus first. 1st level holds a maximum of 2 electrons 2nd level holds a maximum of 8 electrons 3rd level holds a maximum of 8 electrons This electron arrangement is written as 2,8,8. Arrangement of electrons in an atom
- 6. • Each sublevel (s, p, d, f) contains orbitals. • Orbitals are electron-clouds that hold the electrons 90% of the time. • Each orbital can hold TWO electrons. Atomic orbitals Maximum Number of Electrons In Each Sublevel Maximum Number Sublevel Number of Orbitals of Electrons s 1 2 p 3 6 d 5 10 f 7 14
- 7. 1s 2s 3s 4s 5s 6s 7s 2p 3p 4p 5p 6p 3d 4d 5d 6d 4f 5f 1s 2s 2p 3s 3p 4s 3d 4p … 2 2 6 2 6 2 10 6 Electron configuration
- 8. 4f 4d 4p 4s n = 4 3d 3p 3s n = 3 2p 2s n = 2 1s n = 1 Energy Sublevels s s s s p p p d d f 1s22s22p63s23p64s23d104p6… Electron configuration
- 9. • Hund’s Rule • Within a sublevel, place one electron per orbital before pairing them. • “Empty Bus Seat Rule” • Pauli Exclusion Principle • Each orbital can hold TWO electrons with opposite spins. WRONG RIGHT RIGHT WRONG Filling rules for electron orbitals • Aufbau Principle • Electrons fill the lowest energy orbitals first. • “Lazy Tenant Rule” 3d 5s 5p 6p 2s 3s 4s 5s 6s 7s 1s 2p 3p 4p 5p 6p 3d 4d 5d 6d 4f 5f 1s 2s 2p 3s 3p 4s 4p 4d 6s 7s 6d 4f 5f 5d Energy
- 10. As - Arsenic ( Z=33, e=33 ) 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3 Examples and questions Cu - Copper( Z=29, e=29 ) 1s2 2s2 2p6 3s2 3p6 4s1 3d10 Cr - Chromium( Z=24 , e=24 ) 1s2 2s2 2p6 3s2 3p6 4s1 3d5 1s2 2s2 2p6 3s2 3p6 3d6 not 1s2 2s2 2p6 3s2 3p6 4s2 3d4 S - Sulfur ( Z=16, e=16 ) 1s2 2s2 2p6 3s2 3p4 F - Fluorine ( Z=9, e=9 ) 1s2 2s2 2p5
- 12. Thank You!