33877064
Description
Flashcards by JUSTIN KOK SHAO LOONG / UPM, updated more than 1 year ago
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Created by JUSTIN KOK SHAO LOONG / UPM
over 2 years ago
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| Question | Answer |
| Explain the formation of the electromagnetic spectrum. | Electromagnetic radiation comes directly from the Sun. It is a form of energy emitted and absorbed by charged particles, which exhibit wave-like behaviour as it travels through space. Electromagnetic spectrum is the range from the lowest to highest frequency of all types of electromagnetic radiation such as radiowaves, microwaves and ultraviolet rays. |
| Explain the photoelectric effect. | The photoelectric effect is defined as the ejection of electrons from a metal plate when light (photons) falls on the metal surface. The amount of kinetic energy of the electrons depends on the frequency of the light. Related by the formula E = h mew. |
| Describe the formation of the line spectrum of hydrogen atom. | At low pressure, when a vacuum tube is filled with hydrogen gas and an electric current is passed through the tube, a reddish light is emitted. The light produces several lines with a distinguished wavelength in different regions of the electromagnetic spectrum such as visible, ultraviolet and infrared regions. |
| State Bohr's atomic theory | Bohr's atomic theory states that in an atom, electrons revolve around the nucleus in certain definite circular paths called orbitals or shells. Each shell or orbit corresponds to a definite energy. Therefore, these circular orbits are also known as energy levels or energy shells. The energy of an electron is given by the formula...En = -Rhc/n^2 = -RH/n^2 |
| Explain the weaknesses of Bohr's atomic model. | 1. Could not explain the line spectra of atoms containing more than one electron. 2. Could not explain the presence of multiple spectral lines. 3. Could not explain the splitting of spectral lines in a magnetic field (Zeeman effect) and in electric field (Stark effect). THe intensity of these spectral lines was also not explained. 4. Could not explain the dual nature of matter as explained based on De Broglie's concept. 5. Could not explain the uncertainty principle. 6. No conclusion was given to the concept of quantization of energy |
| Explain the differences between continuous spectrum and line spectrum. | Continuous spectrum contains all the wavelengths in each range. It is a distribution of radiant energies of gradually changing wavelengths. Line spectrum only contains a few wavelengths. Line spectrum can be an absorption spectrum or an emission spectrum. |
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