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Structure of Atom|25 Important questions| Class 11 Chemistry |Sourabh Raina

Sourabh Raina・39 minutes read

The text covers various aspects of atomic structure, including the composition of atoms, wavelength calculations, properties of photons, electron orbitals and energy states, and quantum numbers. It delves into topics such as the de Broglie equation, electronic configurations of elements like chromium and copper, and the Heisenberg Uncertainty Principle.

Insights

  • The de Broglie equation relates the wavelength of moving particles to their momentum, highlighting the wave-particle duality of matter and providing a fundamental insight into the behavior of microscopic entities.
  • Quantum numbers, including principal, azimuthal, magnetic, and spin quantum numbers, offer a comprehensive description of electrons in atoms, delineating their energy levels, orbital shapes, spatial orientations, and intrinsic spins, crucial for understanding atomic structure and electron configurations.

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Recent questions

  • What determines the number of protons and neutrons in an atom?

    Mass number and atomic number

  • How is the wavelength of light radiation defined?

    v = frequency * wavelength

  • What is the de Broglie equation for wavelength?

    Lada = h / p

  • What are photons in electromagnetic radiation?

    Small packets of energy

  • What is the ground state of an electron?

    Lowest energy state

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Summary

00:00

Atomic Structure and Quantum Mechanics Explained

  • The number of protons and neutrons in an atom are determined by the mass number and atomic number, with protons represented by z and neutrons calculated as the mass number minus the number of protons.
  • The relationship between velocity, frequency, and wavelength of light radiation is defined by the equation v = frequency * wavelength, with velocity denoted as v, frequency as nya, and wavelength as lada.
  • The de Broglie equation for wavelength states that every moving particle has an associated wavelength, expressed as Lada = h / p or h / (m * v) for microscopic particles like electrons.
  • Photons are small packets of energy emitted by electromagnetic radiation like light, with each photon's energy represented by e = h, where h is Planck's constant.
  • The 3d orbital has higher energy than the 4s orbital due to the higher value of n + l, indicating that the orbital with a greater sum of n + l possesses more energy.
  • The ground state of an electron is its lowest energy state, while the excited state is a higher energy state where electrons occupy higher shells due to increased energy levels.
  • The wavelength of a ball with a mass of 0.1 kg and a velocity of 10 meters per second can be calculated using the de Broglie wavelength equation, resulting in a wavelength of 6.626 x 10^-34 m.
  • The absolute value of the wave function represents the probability of finding an electron at a specific coordinate, with radial nodes indicating regions where electrons are absent and angular nodes denoting planar regions with zero electron probability.
  • The maximum number of emission lines when an excited electron in a hydrogen atom drops to the ground state is calculated using the formula n(n-1)/2, resulting in 15 emission lines.
  • The energy associated with the first orbit in a hydrogen atom is calculated as -8.7 x 10^-20 Joules per atom, while the radius of the Bohr fifth orbit is determined to be 13.25 angstroms.
  • Limitations of Bohr's model include its inability to explain spectra of atoms with multiple electrons, the splitting of spectral lines under magnetic or electric fields, and the formation of molecules through chemical bonds.
  • The structure of d orbitals consists of five types with a double dumbbell shape, with d orbitals like dz^2 having lobes along the z-axis and dx^2-y^2 exhibiting a ring-like shape.
  • Quantum numbers are sets of four numbers providing complete information about an electron in an atom, including the principal quantum number (n) indicating the shell and energy level, and the azimuthal quantum number (l) representing subshells and orbital shapes.
  • The quantum numbers also include the magnetic quantum number (m) specifying the orientation of orbitals in space, and the spin quantum number (s) indicating the electron's spin direction.

13:43

"Quantum Numbers and Electron Orbitals Explained"

  • Shells are divided into subshells based on quantum numbers, determining the number of orbitals and their orientation in space.
  • The formula m = -l2 + l is used to calculate the number of orbitals in each subshell.
  • Electrons are divided into orbitals based on spin, with two electrons per orbital spinning in opposite directions.
  • The maximum number of electrons in s, p, d, and f orbitals are 2, 6, 10, and 14 respectively.
  • Heisenberg Uncertainty Principle states the impossibility of determining both the exact position and momentum of an electron simultaneously.
  • Sets of quantum numbers are analyzed to determine their possibility, considering the values of n, l, and m.
  • Electrons fill orbitals in increasing energy order, with the electronic configuration of phosphorus being detailed.
  • The wavelength of light emitted during electron transitions in a hydrogen atom is calculated using the formula involving the Rydberg constant and energy levels.
  • Hund's Maximum Multiplet Rule dictates the pairing of electrons in degenerate orbitals within the same subshell.
  • The lowest value of n required for a g orbital to exist is determined based on the orbital angular momentum quantum number.

25:48

Quantum Mechanics: Uncertainty, Orbitals, and Energy

  • The formula l is equal to 0 to n - 1 is known.
  • To find the minimum value of l, n should be equal to 5.
  • Question 20 involves calculating the Uncertainty in Velocity of a Wagon of Mass 2000 Cage.
  • Heisenberg uncertainty principle is used to find the uncertainty in velocity.
  • The electronic configuration of chromium is 4s 1 3d 5 due to a half-filled orbital.
  • Copper's electronic configuration is 4s 1 3d 10 due to a fully filled orbital.
  • The angular momentum of a 2p orbital is √2h / 2p.
  • The energy required to remove an electron from the 2nd orbit is 5.45 * 10^-19 joules.
  • The longest wavelength of light needed for this is 3.64 * 10^-5 cm.
  • D-generated orbitals have the same energy if they belong to the same subshell and shell.

37:48

Transition Metals' Electron Configurations and Orbital Rules

  • Iron's electronic configuration is Argon 4s2 3d6. To achieve Fe2+, two electrons are removed from the outermost shell, 4s, resulting in Argon 3d6. Chromium's electronic configuration is Argon 4s1 3d5. To obtain Cr3+, three electrons are removed, first from 4s and then from 3d, leading to Argon 3d3.
  • For n=4, the total number of electrons in the fourth orbital is 32, with 16 orbitals and each containing two electrons. Electrons in the orbitals exhibit opposite spins, with half having a plus half spin and the other half a minus half spin. In the 3s orbital, with n=3 and l=0, only two electrons can be present.
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