Quiz 3 - Early Quantum Theory | Early Quantum Theory
General Chemistry 1 - Quiz 3 - Early Quantum Theory
Which phenomenon led to the first quantized model of the atom by postulating energy levels?
Atomic line spectra, observed as distinct lines rather than a continuous range, indicated that electrons exist in quantized energy levels within atoms. This led to the development of the Bohr model, which proposed that electrons can only occupy certain orbits with discrete energy values.
What aspect of the photoelectric effect challenged classical wave theory of light?
The classical wave theory predicted that light intensity would be the key factor in ejecting electrons from a metal. However, the photoelectric effect demonstrated that there is a frequency threshold that must be met, regardless of intensity, providing evidence for the particle nature of light.
What phenomenon is observed when a beam of electrons is passed through a narrow slit or around an obstacle?
Diffraction occurs when a wave encounters an obstacle or aperture, causing it to spread out and interfere with itself. This phenomenon is observed in electron beams, confirming their wave-like properties.
In the context of early quantum theory, what did Planck's constant revolutionize?
Planck's constant was central to the quantization of energy exchange. It is the proportionality constant in the equation E = h, indicating that the energy of photons is quantized and proportional to their frequency. This was a significant departure from classical physics, which treated energy exchange as continuous.
Which series of lines in the hydrogen emission spectrum are due to transitions to the second energy level?
The Balmer series of lines in the hydrogen emission spectrum arise from electronic transitions to the second energy level from higher levels. These transitions emit light in the visible spectrum and were key in developing the Bohr model of the hydrogen atom.
How did Louis de Broglie's hypothesis bridge the gap between macroscopic and quantum worlds?
Louis de Broglie's hypothesis extended the wave-particle duality concept from photons to matter, proposing that particles, like electrons, also exhibit wave-like properties. This bridged the gap between the behavior of macroscopic objects and that of particles at the quantum level.
What does the diffraction pattern of electrons passing through a narrow slit consist of?
The diffraction pattern of electrons passing through a narrow slit exhibits alternating bright and dark spots, indicating interference effects characteristic of wave behavior.
What is the definition of wavelength in the context of light waves?
Wavelength (λ) is defined as the distance between successive wave peaks in a wave, such as those found in light waves.
Albert Einstein's explanation of the photoelectric effect introduced the idea that light can behave as:
Einstein's explanation of the photoelectric effect suggested that light is composed of discrete packets of energy, called photons, which demonstrated its particle-like behavior. This was a pivotal concept in the development of quantum mechanics.
Which part of the electromagnetic spectrum encompasses wavelengths between approximately 400 nm to 750 nm?
Visible light consists of wavelengths between approximately 400 nm (violet) to 750 nm (red), making it the portion of the electromagnetic spectrum that is visible to the human eye.