7586398
Description
Flashcards by Nitin Ranjan, updated more than 1 year ago
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Created by Nitin Ranjan
almost 8 years ago
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| Question | Answer |
| The postulation of the presence of an indivisible entity of atom was proposed by? | Democritus in ancient Greece, Kanad in ancient India and John Dalton in the modern times. |
| What did the ancient philosophers as well as John Dalton think of atoms? | Though ancient views were philosophical, Dalton too felt that atoms were indivisible largely due to the fact that his theory was based on the then newly profound laws of chemical combinations - the conservation of mass and of definite proportions. |
| What were the cathode tube experiments? What role did they play? | The cathode tube was formulated by Faraday and Crooks - they both believed that elementary charges were responsible for conduction. So, in an evacuated tube under very low pressure and high voltages, discharges were experimented with. these experiments helped to discover electrons and protons. |
| Who discovered electrons? | Sir J J Thomson Thomson proposed the plum pudding model which was a failure. However, he worked extensively on fundamental particles, electric discharges. |
| Who discovered proton? | E. Goldestein |
| Who discovered the nucleus? | E. Rutherford. A scientist par excellence, he propounded the first modern version of atomic structure where electrons revolve around a nucleus, experimentally proved that protons are fundamental particles, his method is used to determine atomic and nuclear radii, he also postulated the existence of neutrons. |
| What were the drawbacks of Rutherford's theory? | |
| Who improvised Rutherford's model? | Neils Bohr A scientist and assistant to Ruthrford, Bohr implemented the newly developed quantum mechanics to state the supremacy of rutherford's model and quantum physics over classical thermodynamics while dealing with atomic scales. |
| Bohr's Hydrogen atom | |
| What was Heisenberg's uncertainity principle? | Heisenberg stated that 'no single physical experiment can be devised to explain everything as an observation' OR... it is impossible to define momentum and position of an electron simultaneously.. so, no serious Bohr's orbits can exist. It met with resistance from many scientists including Albert Einstein himself. |
| What were the drawbaccks of Bohr's model? | 1. Heisenberg's U.P failed some basic concepts behind the hypothesis. 2. Zeeman and Stark Effects 3. Non- applicability on a multi- electron system |
| What was proposed to explain the Zeeman and Stark effects? | The Bohr-Sommerfield model |
| What was the Sommerfield's model? | The principle orbits have many elliptical paths. the electron could transit between these states. This laid the foundation for azimuthal numbers of orbits, the future reference for sub-shells. This could well explain the idea of Zeeman and Stark breakings of spectral lines. |
| who developed the probability postulate? | Max Born |
| Who developed the modern version of atomic model? | Scrodinger |
| What is the modern accepted atomic model? | The Quantum model of atom. It deals with the electron probability density functions. There are no absolute orbits but only defined regions (called orbitals) in which electrons of specific energies are most "probable" to be found. It is more of a mathematical model. |
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