NIRAMAY SHARMA ATOMIC STRUCTURE
ATOMIC STRUCTURE
ATOMIC S TRUCTURE .......................................................................................................................1
Discovery of Subatomic Particles .....................................................................................................1
Atomic Models ................................................................................................................................1
Quantum Mechanical Model.............................................................................................................2
Quantum Numbers ..........................................................................................................................2
Electronic Conf iguration...................................................................................................................2
Important Formulas .........................................................................................................................3
Key Points to Remember .................................................................................................................3
Discovery of Subatomic Particles
Electron Discovery (J.J. Thomson, 1897)
• Cathode ray tube experiments
• Charge-to-mass ratio (e/m) = 1.76 × 10¹¹ C/kg
• Electrons are negatively charged particles
Proton Discovery (Goldstein, 1886)
• Canal ray experiments
• Positively charged particles in nucleus
• Mass ≈ 1836 times that of electron
Neutron Discovery (Chadwick, 1932)
• Neutral particles in nucleus
• Mass approximately equal to proton
Atomic Models
Thomson's Model (1898)
• "Plum pudding" model
• Electrons embedded in positive sphere
• Limitations: couldn't explain atomic stability
Rutherford's Model (1911)
• Gold f oil experiment
1
ATOMIC STRUCTURE
ATOMIC S TRUCTURE .......................................................................................................................1
Discovery of Subatomic Particles .....................................................................................................1
Atomic Models ................................................................................................................................1
Quantum Mechanical Model.............................................................................................................2
Quantum Numbers ..........................................................................................................................2
Electronic Conf iguration...................................................................................................................2
Important Formulas .........................................................................................................................3
Key Points to Remember .................................................................................................................3
Discovery of Subatomic Particles
Electron Discovery (J.J. Thomson, 1897)
• Cathode ray tube experiments
• Charge-to-mass ratio (e/m) = 1.76 × 10¹¹ C/kg
• Electrons are negatively charged particles
Proton Discovery (Goldstein, 1886)
• Canal ray experiments
• Positively charged particles in nucleus
• Mass ≈ 1836 times that of electron
Neutron Discovery (Chadwick, 1932)
• Neutral particles in nucleus
• Mass approximately equal to proton
Atomic Models
Thomson's Model (1898)
• "Plum pudding" model
• Electrons embedded in positive sphere
• Limitations: couldn't explain atomic stability
Rutherford's Model (1911)
• Gold f oil experiment
1
