Class 11 First Session: Atomic Structure

Introduction

• Analysis of tough questions from the last year
• New question set and solutions
• Practice videos and PDF solutions

Atomic Structure

• Calculation part
• Study of energy levels, wavelengths, and frequency
• Calculation and graph

Important Points

• Importance of maintaining enthusiasm in Class 11 syllabus
• Rotating questions between Bohr's model, Hydrogen spectrum, etc.
• Each atomic model: Key fundamentals

Weightage (JE Mains and JE Advanced)

• Average weightage: 4%
• Bohr's model and its related questions in JE Exam
• Consistently asked in previous years

Dalton's Atomic Theory

• Postulates
  • Matter is made up of small indivisible particles (Beyond the theory of redox reaction outcomes)
  • Atom can neither be created nor destroyed (Practically different in isotopes cases)
  • Atoms of the same element are identical in all respects
  • Atoms are not unbreakable; electrons, protons, and neutrons can break
• Limitations
  • Isotopes: Isotope deficiency
  • Argon and Calcium case
  • Isobars: tampering with isobars
  • Allotropes: description of different forms

Cathode Experiment

• Discharge tube, vacuum pump, high voltage generator
• Electron push at cathode
• Cathode rays: high velocity, straight path, green glow, shadow
• Mechanical effect, statement of charged particles

Millikan's Oil Drop Experiment

• Calculation of e/m: determination of charge and mass
• Nature determination of cathode ray

Thomson Model

• Summarization
• Limitations: Scattering experiments that could not justify the Thomson model

Rutherford Model

• Alpha particle experiment
• Description of the model
• Head-on collision events
• Failure of Maxwell theory and its limitations

Heisenberg - Uncertainty Principle

• It's not possible to state the exact position and momentum of a particle
• Combination of error

Planck's Quantum Theory

• Energy and time relationship
• e=hν equation  

De Broglie Hypothesis

• Dual nature of particle and wave
• Equation:
  • λ=h/p  

Bohr's Atomic Model

• Quantization (angular momentum as a multiple of H/2π)
• Electronic transition (from higher to lower energy level)

Quantum Mechanical Model

• Quantum principal number: n (orbit)
• Azimuthal quantum number: l (sub-orbit)
• Magnetic quantum number: ml (orbital)
• l (shape along with sub-orbit)
• ml (magnetic quantum number - orientation of the entire orbital)

Spectrum

Hydrogen Spectrum

• Spectral lines
• Series and features: Lyman, Balmer, Paschen
• Lyman (ultraviolet)
• Balmer (visible)

Radial Wave Functions and Graphs

• Psi wave function
• The value of Psi square: probability density  
• Angular nodes: nodal planes
• Radial nodes: spherical nodes

Questions

• Finding the distance between nodes

Formula Recall

• V = n/2πr (orbital velocity)
• Angular momentum = mvr = nh/2π
• Electronic transition: sequential Stark series and addition of greens