Q: What is the ground state of an atom?
A: The ground state is when all electrons occupy the lowest possible energy levels available to them.
Q: What is an excited state?
A: An excited state occurs when one or more electrons absorb energy and move to higher energy levels.
Q: Why can electrons only absorb specific amounts of energy?
Because electron energy levels are quantised — electrons can only move between fixed energy levels, not exist between them.
Q: Why does every magnesium atom absorb the same energies?
Because all magnesium atoms have identical energy level structures, so the allowed transitions are the same.
Q: Why are excited electrons unstable?
Higher energy states are less stable, so electrons naturally return to lower energy levels, releasing energy as photons.
Q: What is an emission spectrum?
A: The set of discrete wavelengths (lines) emitted when excited electrons return to lower energy levels.
Q: Why does each element have a unique line spectrum?
A: Each element has a unique electron configuration, meaning unique energy levels and allowed transitions.
Q: How does energy gap size affect colour?
Large energy gap → high energy photon → short wavelength (violet/UV)
Small energy gap → low energy photon → long wavelength (red)
Q: What determines the wavelength of emitted light?
A: The energy difference between the two energy levels involved in the transition.
Q: Why is hydrogen important in spectroscopy?
*research this
A: Hydrogen has only one electron, so its energy levels can be calculated exactly.
Q: What is the Lyman series?
A: Transitions from higher levels to n = 1 → ultraviolet region → highest energy photons.
Q: What is the Balmer series?
A: Transitions from higher levels to n = 2 → visible region (and some UV).
Q: What is the Paschen series?
A: Transitions from higher levels to n = 3 → infrared region.
Q: Why do hydrogen-like ions (He⁺, Li²⁺) have shifted spectral lines?
A: They have higher nuclear charge, increasing attraction → larger energy gaps → shorter wavelengths.
Q: Why don’t multi-electron atoms follow simple 1/n² patterns?
A: Electron–electron repulsion and sublevel splitting make their energy structures more complex.
Q: What is a flame test?
A: An analytical emission technique used to identify elements based on flame colour.
Q: What causes flame colour?
A: Excited valence electrons returning to lower energy levels emit visible photons.
Q: Why are valence electrons mainly involved in flame tests?
A: They require less energy to excite compared to inner electrons.
Q: Why can sodium mask other elements in a flame test?
A: Sodium produces very intense yellow emission lines that overpower weaker emissions.
Q: What are limitations of flame tests?
Some emissions are outside visible spectrum
Colours may overlap
Some lines are too weak to detect
Q: How do line spectra prove energy is quantised?
A: Only specific wavelengths are emitted, meaning only specific energy differences exist.
Why don’t atoms produce continuous spectra in emission?
A: Because electrons can only transition between fixed energy levels.
What did the Bohr model propose?
Electrons orbit in fixed energy levels
Energy is absorbed/emitted during transitions
Energy difference determines wavelength
Why did emission spectra support the Bohr model?
Discrete line spectra could only be explained by quantised energy levels.
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Week 2.1: The Atom31
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Week 2.0 Development of the models of the atom40
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Week 3.0 Electron shells and configurations28
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Elemental spectroscopy30
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Isotopes32
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Week 5: Periodic Trends25
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More periodic trends but this time it is actually periodic trends37
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Matter and properties32
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Separation Techniques36
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Mettalic bonding21
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Ionic Bonding26
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Naming chemical compunds31
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Common Chemical Reactions35
