Quantum Concepts
Quantum physics reveals that at the subatomic scale, matter and energy behave in ways that defy classical physics, including wave-particle duality and quantised energy levels.
What You Need to Know
Key Concept Diagram
Quantum physics describes the behaviour of matter and energy at the atomic and subatomic scale
Wave-particle duality: particles like electrons exhibit both wave and particle properties depending on how they are observed
Energy is quantised: electrons in atoms can only occupy specific energy levels, not continuous values
The photoelectric effect, explained by Einstein, showed light travels in discrete packets called photons
The Heisenberg uncertainty principle states we cannot simultaneously know the exact position and momentum of a particle
Key Vocabulary
Quantum
The smallest discrete unit of a physical quantity, especially energy
Wave-particle duality
The principle that all matter and light exhibit both wave-like and particle-like properties
Photon
A quantum (packet) of electromagnetic energy; the basic unit of light
Uncertainty principle
Heisenberg's principle that the position and momentum of a particle cannot both be precisely known at the same time
Knowledge Check
Select the correct answer for each question. Click "Check Answer" to see if you are right.
Question 1
What did Einstein's explanation of the photoelectric effect establish?
Question 2
Wave-particle duality means that electrons:
Question 3
What does the quantisation of energy in an atom mean?
Key Concepts Summary
- ●Quantum physics describes the behaviour of matter and energy at the atomic and subatomic scale
- ●Wave-particle duality: particles like electrons exhibit both wave and particle properties depending on how they are observed
- ●Energy is quantised: electrons in atoms can only occupy specific energy levels, not continuous values
- ●The photoelectric effect, explained by Einstein, showed light travels in discrete packets called photons
- ●The Heisenberg uncertainty principle states we cannot simultaneously know the exact position and momentum of a particle