SCH4U : ATOMIC THEORY
COMPREHENSIVE STUDY GUIDE 2026 FULL
QUESTIONS AND SOLUTIONS GRADED A+
◍ Speed of Light (in empty space).
Answer: 3 x 10⁸ m/s
◍ How does visible light interact with electrons?.
Answer: 1. EXCITES electron--> light makes electron jump a valence
shell2. RETURNS to ground state--> electron returns back to shell, EMITS
LIGHT WAVES (different color = different light = different PEL)--->
depending on jump from different principal energy levels, the light will be
differentex: n=2→n=1 vs. n=3→n=1 vs. n=3→n=2
◍ If λ (wavelength) is SHORT, then....
Answer: HIGH (frequency)HIGH E (energy)
◍ Plum Pudding Model.
Answer: JJ ThomsonAtoms are electrically neutral, so there must be positive
charge with the electrons- Proposed electrons were embedded in gel-like
positive charge
◍ What is the relationship between wavelength (λ) and frequency (v)?.
Answer: Inverse (↑ = ↓)
◍ Speed of Light Symbol.
Answer: C (m/s)
◍ If λ (wavelength) is LONG, then....
Answer: LOW (frequency)LOW E (energy)
◍ What electrons do cations lose first?.
Answer: VALENCE electrons, NOT necessarily the last ones in the electron
, configuration
◍ Hertz.
Answer: Hz = s⁻¹ (1/s)for FREQUENCY, waves that pass per unit time
◍ Quantum Model.
Answer: Heisenberg —> we can only determine the probability of where an
electron should be locatedElectrons are given “addresses”Broad —>
specificUses electron orbitals to describe an electron’s locationPrincipal
energy level: an electron’s approximate distance from nucleus (n = 1,2,3)-
Corresponds to periods (rows) on periodic tableOrbital shapes (sublevels):
shape of where the electron can be found within an energy levelS, p, d, fS =
1 orbitalP = 3 orbitals D = 5 orbitals F = 7 orbitals Each orbital can hold 2
electronsElectron orientation: electron can be facing up or down
◍ The Greeks.
Answer: Leuccipus + DemocritusTheory: If you divided matter into smaller
and smaller pieces, you would eventually end up with indivisible particles
(“atomos”)
◍ Energy Symbol.
Answer: E (J)
◍ Bohr Model.
Answer: Niels BohrGoal: Figure out where outside of the nucleus electrons
exist Studied through the emission spectra of electronsPlanetary model:
electrons orbit the nucleus in energy levels BECAUSE: Electrons have
wave-particle dualityCan absorb light & energy Both a wave and a
particleElectron is excited by light energy, jumps out of valence
shellElectron returns to original state & emits light as an electromagnetic
wave
◍ What is the maximum charge of transition metals (# of electrons lost)?.
Answer: When all S+D LEVELS ARE EMPTY
◍ Nanometer.
Answer: nm = 1E9 m
COMPREHENSIVE STUDY GUIDE 2026 FULL
QUESTIONS AND SOLUTIONS GRADED A+
◍ Speed of Light (in empty space).
Answer: 3 x 10⁸ m/s
◍ How does visible light interact with electrons?.
Answer: 1. EXCITES electron--> light makes electron jump a valence
shell2. RETURNS to ground state--> electron returns back to shell, EMITS
LIGHT WAVES (different color = different light = different PEL)--->
depending on jump from different principal energy levels, the light will be
differentex: n=2→n=1 vs. n=3→n=1 vs. n=3→n=2
◍ If λ (wavelength) is SHORT, then....
Answer: HIGH (frequency)HIGH E (energy)
◍ Plum Pudding Model.
Answer: JJ ThomsonAtoms are electrically neutral, so there must be positive
charge with the electrons- Proposed electrons were embedded in gel-like
positive charge
◍ What is the relationship between wavelength (λ) and frequency (v)?.
Answer: Inverse (↑ = ↓)
◍ Speed of Light Symbol.
Answer: C (m/s)
◍ If λ (wavelength) is LONG, then....
Answer: LOW (frequency)LOW E (energy)
◍ What electrons do cations lose first?.
Answer: VALENCE electrons, NOT necessarily the last ones in the electron
, configuration
◍ Hertz.
Answer: Hz = s⁻¹ (1/s)for FREQUENCY, waves that pass per unit time
◍ Quantum Model.
Answer: Heisenberg —> we can only determine the probability of where an
electron should be locatedElectrons are given “addresses”Broad —>
specificUses electron orbitals to describe an electron’s locationPrincipal
energy level: an electron’s approximate distance from nucleus (n = 1,2,3)-
Corresponds to periods (rows) on periodic tableOrbital shapes (sublevels):
shape of where the electron can be found within an energy levelS, p, d, fS =
1 orbitalP = 3 orbitals D = 5 orbitals F = 7 orbitals Each orbital can hold 2
electronsElectron orientation: electron can be facing up or down
◍ The Greeks.
Answer: Leuccipus + DemocritusTheory: If you divided matter into smaller
and smaller pieces, you would eventually end up with indivisible particles
(“atomos”)
◍ Energy Symbol.
Answer: E (J)
◍ Bohr Model.
Answer: Niels BohrGoal: Figure out where outside of the nucleus electrons
exist Studied through the emission spectra of electronsPlanetary model:
electrons orbit the nucleus in energy levels BECAUSE: Electrons have
wave-particle dualityCan absorb light & energy Both a wave and a
particleElectron is excited by light energy, jumps out of valence
shellElectron returns to original state & emits light as an electromagnetic
wave
◍ What is the maximum charge of transition metals (# of electrons lost)?.
Answer: When all S+D LEVELS ARE EMPTY
◍ Nanometer.
Answer: nm = 1E9 m
