7.1 Energy Levels Flashcards
What are emission spectrum?
Set of wavelengths of light emitted by gases.
Emit light when heated to high temperature or exposed to high electric field.
Light emitted consists of discrete set of specific wavelengths.
What are absorption spectrum?
Set of wavelengths of light that are absorbed when white light is transmitted through a gas.
Wavelengths corresponds exactly to wavelengths in emission spectrum.
What is a photon?
Particle of light.
Bundle of energy and momentum.
Energy of photon given by E=hf.
What are energy levels?
Energy of atom is discrete, can only have specific values. Possible energies atom can have are energy levels.
What are atomic transitions?
Photon is emitted when atom makes transition from higher energy level to lower energy level. Photon carries away energy equal to difference in energy of levels involved in transition.
What is evidence for energy levels?
Existence of discrete energy spectra.
Every transition from high to lower energy level emits one photon.
What are the forces acting within a nucleus?
Electrical repulsion force between protons.
Strong nuclear forces acting between nucleons, mostly attractive.
Weak nuclear force responsible for beta decay.
What is the range of the strong force?
Short range, a nucleon only attracts immediate neighbours.
What is the range of the electrical force?
Infinite range, implies any proton repels all other protons in nucleus.
What does the presence of the strong nuclear force prevent?
Prevents the electrical force ripping the nucleus apart.
Why is gravitational force negligible in the nucleus?
Because masses involves are so small.
