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Class 11 Structure of Atom worksheet
CBSE Chemistry. Atomic particles, photons, Bohr model, hydrogen spectrum, quantum numbers, configurations. Every sheet has 20 questions in three sections and an answer key, and the numbers change every time.
Sample questions
Real questions from this chapter, as the app sets them. Tap Answer to see the answer and working.
Section A · multiple choice
- 1.
Who discovered the electron, using cathode rays?
- James Chadwick
- Niels Bohr
- Ernest Rutherford
- J. J. Thomson
Answer
(d) J. J. Thomson
- 2.
The number of electrons in ²⁴₁₂Mg²⁺ is:
- 10
- 12
- 24
- 11
Answer
(a) 10
Z = 12, A = 24: protons 12, neutrons 24 − 12 = 12, electrons 12 − 2 = 10
- 3.
The energy of one photon of light of wavelength 400 nm is: (h = 6.626 × 10⁻³⁴ J s, c = 3.0 × 10⁸ m/s)
- 4.97 × 10⁻¹⁸ J
- 4.97 × 10⁻¹⁶ J
- 4.97 × 10⁻²⁰ J
- 4.97 × 10⁻¹⁹ J
Answer
(d) 4.97 × 10⁻¹⁹ J
E = hc/λ, with λ in metres
Section B · short answer
- 4.
State Hund’s rule of maximum multiplicity.
Answer
Electrons enter the orbitals of a subshell singly, with parallel spins, before any pairing begins.
- 5.
Find the frequency and the wavenumber of radiation of wavelength 500 nm. (c = 3.0 × 10⁸ m/s)
Answer
ν = 6.00 × 10¹⁴ Hz; ν̄ = 2.00 × 10⁶ m⁻¹
ν = c/λ; ν̄ = 1/λ (λ in metres)
Section C · long answer
- 6.
Describe Rutherford’s α-particle scattering experiment. What did it show, and what was the main drawback of his model?
Answer
A thin gold foil was bombarded with α-particles. Most passed straight through, a few were deflected through small angles, and very few (about 1 in 20,000) bounced back. So most of the atom is empty space, with its positive charge and almost all its mass in a tiny nucleus; electrons move around it. Drawback: an electron moving in a circle should radiate energy and spiral into the nucleus, so the model cannot explain the stability of the atom (or line spectra).
Fresh sheets for your child
In the app, every Structure of Atom sheet is new: the app remembers the questions your child has already had and leaves them out. Print the sheet as a PDF, or use notebook mode and write the answers in a notebook.
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