Electron Transitions & Emission Spectra — Practice · Grade 11 Science
Chapter: Atoms, Electrons & PeriodicityWhat this practice covers
By the end of Electron Transitions & Emission Spectra you should be able to:
- I can connect spectral lines to allowed electron energy changes.
- I can calculate photon energy and evaluate a pattern match.
8 questions, numeric and written answer, each with a worked explanation.
Vocabulary used: ground state, excited state, photon.
Problem 1
Hints
Write the relationship first; substitute with consistent units.
Answer and explanation
4 energy units
7−3 = 4.
Problem 2
Answer and explanation
Only allowed state differences occur; each gives a photon with a specific frequency.
Response criteria
- State a scientifically accurate conclusion.
- Show the calculation or mechanism that supports it.
- Include units, conditions, or limits where relevant.
Problem 3
Hints
List the given quantities, select a relationship, and check units before substituting.
Answer and explanation
6 energy units
10−4=6.
Problem 4
Answer and explanation
Match additional lines, check resolution and calibration, and evaluate whether a mixture could give the same subset.
Response criteria
- State a scientifically accurate conclusion.
- Show the calculation or mechanism that supports it.
- Include units, conditions, or limits where relevant.
Problem 5
Hints
Emission lowers atomic energy; absorption raises it.
Answer and explanation
E=hf=3.315×10⁻¹⁹ J, about 3.3×10⁻¹⁹ J.
Problem 6
Hints
State what the supplied observations or conditions establish, and separate that from any assumption.
Answer and explanation
Different allowed transitions have different energy differences, producing different photon frequencies.
Problem 7
Answer and explanation
Several positions constrain the species pattern and reduce ambiguity from overlap, intensity differences and visual perception.
A low-density excited atomic gas can emit discrete spectral lines associated with electronic transitions. A continuous spectrum spans a broad range rather than only isolated ideal lines. Line positions help identify species when compared with calibrated reference patterns; intensity also depends on population, excitation, detection and other conditions. Overlapping species or broadening can complicate an observed spectrum. A colored stripe diagram is a schematic key to positions, not an actual camera record or a guarantee of equal line intensities.
Several positions constrain the species pattern and reduce ambiguity from overlap, intensity differences and visual perception.
Response criteria
- Interpret labels, structures, axes, units and directions correctly.
- Explain the chemistry relationship or mechanism.
- Respect stated assumptions and distinguish observation from inference.
Problem 8
Answer and explanation
The first photon has 3.0 eV, or about 4.81×10⁻¹⁹ J, giving λ≈4.14×10⁻⁷ m =414 nm. A later allowed 1.5-to-0 transition could emit a 1.5 eV photon; the selected model does not supply transition probabilities.
The first photon has 3.0 eV, or about 4.81×10⁻¹⁹ J, giving λ≈4.14×10⁻⁷ m =414 nm. A later allowed 1.5-to-0 transition could emit a 1.5 eV photon; the selected model does not supply transition probabilities.
Response criteria
- Use the stated measurements or conditions, with correct units.
- Connect the result to the chemical mechanism or evidence relationship.
- Identify the assumption, model limit or further evidence requested.