Electrons in the Atom

What do we know about electrons? What is the basic information about electrons (charge, mass, location)? Explain the Bohr model structure. Draw a model for carbon. Label the valence electrons. Draw a Lewis dot structure for carbon. What is the energy released when a hydrogen electron moves from n=6 to n=2? What is the difference between ground state and excited state? How do electrons move between these two states? What does it mean for an atom to become an ion? How does the charge relate to the change in electrons?

Quantum Mechanics Using a mathematical description of the wavelike behavior of particles on the atomic level Electrons are located in orbitals (spaces where they have a high probability of being found) Each orbital is described by three quantum numbers

Atomic Orbitals Region of space in which there is a high probability of finding an electron Principal quantum number, n Angular momentum quantum number l Magnetic quantum number ml

Principal Energy levels Quantum number, n Orbitals with the same value of n are in the same shell n= 1, 2, 3, 4, etc. Energy level n Max number electrons 1 2 8 3 18 4 32

Angular Momentum quantum number l Orbitals with the same value of n and l are in the same subshell Different shaped spaces within the sublevels s is spherical (1 orbital) p is dumbbell (3 orbitals) d varies (5 orbitals) f more complex (7 orbitals) (2 electrons per orbital)

Summary of Principal Energy Levels, Sublevels, and Orbitals Energy level n Number of sublevels Type of sublevel 1 1s 2 2s, 2p 3 3s, 3p, 3d 4 4s, 4p, 4d, 4f

Magnetic quantum number ml Distinguishes orbitals of given n and l, of given energy and shape but having different orientation in space Values are integers from -1 to +1

Magnetic quantum number ms Refers to the two possible orientations of the spin axis of an electron Values are +1/2 and -1/2 Each orbital can contain two electrons with opposite spins “Up” “Down” Spintronics

Keeping Track of Electrons All this information about electrons is very hard to visualize and understand Electron configuration and orbital diagrams can help Electron configuration: description of the orbitals occupied by electrons

Three rules and electron configuration Aufbau Principle- Pauli Exclusion Principal – Hund’s Rule – (Page 133-134)

Three rules and electron configuration Aufbau Principle- fill lowest energy level first Pauli Exclusion Principal – 2 electrons per orbital with opposite spin Hund’s Rule – Bus Seat, electrons occupy orbitals in the same energy level going in the same spin direction (Page 133-134)

Energy Levels & Orbitals Sublevels Energy Levels Orbitals 16

Aufbau diagram

Orbital diagram

Electron configuration 1s22s22p63s1 Sodium

Electron Configuration Video Periodic Table Song