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CLASS 11 -- CHEMISTRY CHAPTER 5: ATOMIC STRUCTURE

This is a discussion on CLASS 11 -- CHEMISTRY CHAPTER 5: ATOMIC STRUCTURE within the 11th forums, part of the Classes category; CLASS 11 -- CHEMISTRY CHAPTER 5: ATOMIC STRUCTURE SHORT ANSWER QUESTION Q1. Cathode rays are independent of the nature of ...

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    CLASS 11 -- CHEMISTRY CHAPTER 5: ATOMIC STRUCTURE

    CLASS 11 -- CHEMISTRY
    CHAPTER 5: ATOMIC STRUCTURE
    SHORT ANSWER QUESTION

    Q1. Cathode rays are independent of the nature of gas used in the discharge tube

    Ans. all molecules and atoms contain electrons which are cathode ray particles and all electrons have same nature no mater from what atom or molecule
    they are ejected. That is why nature of cathode ray does not depend on the nature of the gas used in the discharge tube.

    Q2. anode rays or canal rays are not produced from the anode.

    Ans. canal rays consist of gaseous ions. These gaseous ions are produced when one or more electrons are ejected from gaseous atoms or molecules. These ions are not produced or ejected from anode.

    Q3. why subatomic particles are called fundamental particles.

    Ans. not all sub-atomic particles are called fundamental, neutrons and protons are consist of quarks. Quarks are the fundamental in this case.

    Q4. Heavier positively charged alpha particles are less deflected in electric field.

    Ans. two particles having same charge but different masses suffer different deflection in the same magnetic field provided they have same kinetic energy. Heavier particles will suffer less deflection due to greater mass.

    Q6. Atomic spectra are also line spectra.

    Ans. electrons are present in specific energy levels in atom. When electrons jump from lower to the higher energy level, they absorb photons of specific energy. Thus these wavelengths will be missing in transmitted light and the spectrum obtained will be line absorption spectrum. In the same way when electrons jump from higher level to the lower level, photons of specific wavelength are emitted. This occurs during de-excitation of atoms. Spectrum obtained in this case will be line emission spectrum.

    Q7. What is the difference between line emission spectrum and line absorption spectrum?

    ans. Electrons are present in specific energy levels in atom. When electrons jump from lower to the higher energy level, they absorb photons of specific energy. Thus these wavelengths will be missing in transmitted light and the spectrum obtained will be line absorption spectrum. In the same way when electrons jump from higher level to the lower level, photons of specific wavelength are emitted. This occurs during de-excitation of atoms. Spectrum obtained in this case will be line emission spectrum.

    Q8. At finite line spectrum become continuous.

    Ans. the difference between the energy levels at infinity is so small that spectrum obtained due to the jumping of electrons in this region is continuous.

    Q9. Electron behaves as wave as well as particle.

    Ans. in 1923-24 Louis de-Broglie suggested that if light, which is electromagnetic radiation, can behave like particles than particle may act like waves. He argued that light has a dual nature i.e. sometimes it behaves like waves and sometimes like particles. Light behaves like particles in photoelectric effect and Compton Effect while it behaves like waves in interference and diffraction. De-Broglie derived an equation for wavelength of the wave, associated with a particle like electron, proton etc.
    = h / mv

    Q10. What is the difference between orbit and orbital?

    Orbit:
    i. it is definite circular path of an electron around the nucleus of an atom.
    ii. An orbit indicates an exact position of an electron in an atom.
    iii. It is against Heisenberg's uncertainty principle.
    iv. It represents the planar motion of the electron.
    v. the maximum number of electrons in an orbit is equal to 2nsquare , where n is the number of the orbit.
    vi. Orbits are circular in shape.
    Orbital:
    i. it is the region around the nucleus within which the probability of finding an electron with a certain energy is maximum.
    ii. An orbital does not specify an exact position of an electron in an atom because of the wave nature of electron.
    iii. It is in accordance with the Heisenberg's uncertainty principle.
    iv. It represents the three dimensional motion of the electrons. Both electrons in an orbital have opposite spin.
    vi. Orbitals have different shapes. For example, s-orbitals are spherical; p-orbitals are dumb-bell shaped.



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