BackBohr Model, Electron Shells, and Absorption/Emission in Atomic Structure
Study Guide - Smart Notes
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Bohr Model of the Atom
Introduction to the Bohr Model
The Bohr Model describes the atom as electrons traveling in circular orbits (shells) around the nucleus. Each shell is associated with a specific energy level, and electrons in different shells possess different amounts of potential energy.
Shell (n): A grouping of electrons surrounding the nucleus, defined by the principal quantum number n.
Potential Energy: The energy an object possesses due to its position; in atoms, this refers to the energy of electrons in different shells.
Key Features of the Bohr Model
Energy Levels: Each shell (n = 1, 2, 3, ...) corresponds to a specific energy level.
Electron Configuration: Electrons fill shells starting from the lowest energy (closest to the nucleus).
Protons: Positively charged particles in the nucleus.
Neutrons: Neutral particles in the nucleus.
Electrons: Negatively charged particles in shells around the nucleus.
Example: Electron Shells
Consider an atom with electrons in shells n = 1, 2, and 3. The electron furthest from the nucleus is in the shell with the highest value of n.
Example Question: What is the value of n for the electron furthest from the nucleus? Answer: The largest value of n present (e.g., n = 3).
Absorption and Emission of Energy
Electron Transitions
Electrons can move between shells by absorbing or emitting energy. These transitions are fundamental to understanding atomic spectra and chemical behavior.
Absorption: When an electron absorbs energy, it jumps from a lower-numbered shell to a higher-numbered shell (moves up).
Emission: When an electron emits energy, it falls from a higher-numbered shell to a lower-numbered shell (moves down).
Energy and Electron Transitions
Greatest Energy Transitions: The largest energy change occurs when an electron moves between shells that are farthest apart (e.g., n = 1 to n = 4).
Energy Equation: The energy change for an electron transition is given by: where is the Rydberg constant, is the initial shell, and is the final shell.
Practice Examples
Absorption Example: n = 1 to n = 3 (electron moves up, absorbs energy).
Emission Example: n = 3 to n = 1 (electron moves down, emits energy).
Greatest Energy Absorption: n = 1 to n = 4 (largest jump, greatest energy absorbed).
Absorption & Emission Table
The following table summarizes the differences between absorption and emission:
Process | Electron Movement | Energy Change | Shell Transition |
|---|---|---|---|
Absorption | Jumps to higher shell | Energy absorbed | Up (e.g., n = 1 to n = 3) |
Emission | Falls to lower shell | Energy released | Down (e.g., n = 3 to n = 1) |
Summary of Key Terms
Bohr Model: Atomic model with electrons in quantized shells.
Shell (n): Principal quantum number indicating electron energy level.
Absorption: Electron gains energy, moves to higher shell.
Emission: Electron loses energy, moves to lower shell.
Additional info: The notes provide foundational concepts for understanding atomic structure and electron transitions, which are essential for GOB Chemistry students.
