Ch.7 - Quantum MechanicsWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Solution: What is the threshold frequency for sodium metal if a photon with frequency 6.66 × 1014 s−1 ejects an electron with 7.74 × 10 −20 J kinetic energy? Will the photoelectric effect be observed if sodium

Problem

What is the threshold frequency for sodium metal if a photon with frequency 6.66 × 1014 s−1 ejects an electron with 7.74 × 10 −20 J kinetic energy? Will the photoelectric effect be observed if sodium is exposed to orange light?

Solution

Recall: According to the photoelectric effect, an electron can be ejected from the surface of a metal if it's hit with photons of sufficient energy. The kinetic energy (KE) of the ejected electron is related to the energy of the photon (Ephoton) hitting the metal surface by this equation:

(1) 

where φ = work function of the metal, which is the minimum energy of a photon that is needed to eject an electron. The threshold frequency, v0, of a metal is the minimum frequency needed to eject an electron and is given by:

(2) 

where h = Planck's constant (6.626 × 10–34 J • s).

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