Advanced Level Atomic Structure Questions

1. An ion has 54 electrons and 76 neutrons. Its mass number is 130. Calculate:

a) The number of protons

b) The charge on the ion

c) The atomic number of the element

a) 54 protons, -2 charge, 54 atomic number
b) 56 protons, +2 charge, 56 atomic number
c) 76 protons, +22 charge, 76 atomic number
d) 130 protons, +76 charge, 130 atomic number

2. An element exists as two isotopes: 69% of mass number 63 and 31% of mass number 65. Calculate its relative atomic mass.

a) 63.31
b) 63.62
c) 64.00
d) 64.31

3. Given that an electron in the first energy level has -13.6 eV of energy, and in the second level -3.4 eV, calculate the energy and frequency of the photon emitted when an electron moves from level 2 to level 1. (h = 6.63 × 10⁻³⁴ Js, 1 eV = 1.6 × 10⁻¹⁹ J)

a) 10.2 eV, 2.47 × 10¹⁵ Hz
b) 17 eV, 4.11 × 10¹⁵ Hz
c) -10.2 eV, 2.47 × 10¹⁵ Hz
d) 3.4 eV, 8.22 × 10¹⁴ Hz

4. Explain why Rutherford's alpha particle scattering experiment suggested a nuclear model, but could not have provided evidence for energy levels or neutrons:

a) The experiment only showed deflection of charged particles, indicating mass and charge distribution but not internal structure or neutral particles
b) The alpha particles weren't energetic enough to probe electron arrangement or nuclear composition
c) The gold foil was too thick to allow detailed analysis of atomic structure
d) The detection methods weren't sophisticated enough to observe electron behavior

5. A sample contains 1000 radioactive atoms at t=0. After 20 minutes, 125 atoms remain. Calculate:

a) The half-life

b) The decay constant

c) The time for 75% decay

a) 5 mins, 0.139 min⁻¹, 10 mins
b) 10 mins, 0.069 min⁻¹, 20 mins
c) 6.7 mins, 0.104 min⁻¹, 13.4 mins
d) 4 mins, 0.173 min⁻¹, 8 mins

6. Three different ionized atoms all have 36 electrons. One has mass number 85, another 86, and another 87. What can you deduce about these atoms?

a) They are isotopes of the same element with +2 charge
b) They are different elements with the same charge
c) They are isotopes of krypton with +2 charge
d) They must be different elements as they have different mass numbers

7. Given that the binding energy per nucleon peaks around mass number 56, explain why both fusion of light nuclei and fission of heavy nuclei can release energy:

a) Because any nuclear reaction releases energy
b) Because moving toward mass number 56 from either direction increases average binding energy per nucleon
c) Because both reactions involve breaking nuclear bonds
d) Because both reactions involve forming new nuclear bonds

8. An electron transitions from the n=4 to n=2 energy level in a hydrogen atom. How many different possible wavelengths of electromagnetic radiation could be emitted in this process?

a) 1
b) 2
c) 3
d) 4

9. A doubly ionized atom has 18 electrons and mass number 40. Given that it has 22 neutrons, what element is it and what was its original atomic structure?

a) Calcium, originally with 20 protons, 20 electrons
b) Argon, originally with 18 protons, 18 electrons
c) Potassium, originally with 19 protons, 19 electrons
d) Scandium, originally with 21 protons, 21 electrons

10. Using quantum numbers, how many electrons can occupy the third electron shell? Explain your reasoning considering the s, p, and d subshells:

a) 8 electrons (one s orbital and three p orbitals)
b) 18 electrons (one s orbital, three p orbitals, and five d orbitals)
c) 32 electrons (including f orbitals)
d) 6 electrons (three p orbitals only)