Atomic Models

14 soru

Soru 1Soru

Match each atomic model with its key defining feature or experimental foundation.

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Öğeler

Thomson Model
Rutherford Model
Bohr Model
Quantum Wave Model

Eşleşmeler

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Cevap

Thomson Model matches with electrons embedded in a positive sphere; Rutherford Model matches with the dense positive nucleus discovered via alpha particle scattering; Bohr Model matches with quantized non-radiating energy levels; Quantum Wave Model matches with standing matter waves in electron orbits.
Each atomic model corresponds directly to its historic milestone: Thomson proposed electrons scattered inside a uniform sphere of positive charge; Rutherford discovered the compact positive nucleus through alpha scattering experiments; Bohr introduced quantized stationary states to account for emission spectral lines; and the Quantum Wave Model integrated de Broglie matter wave harmonics into orbital mechanics.

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1
Identify Thomson's Plum Pudding Model features
Describes electrons distributed inside a broad, uniform cloud/sphere of positive charge.
Formulated after J.J. Thomson discovered the electron before the nucleus was known.
2
Identify Rutherford's Nuclear Model features
Demonstrated that positive charge is concentrated in a tiny nucleus because alpha particles bounced back at large angles.
Geiger-Marsden alpha scattering experiment disproved the uniform charge distribution model.
3
Identify Bohr's Model features
Postulated quantized non-radiating stationary orbits where angular momentum is restricted to integral multiples of h/2πh / 2\pi.
Successfully explained the discrete wavelengths of the hydrogen emission spectrum.
4
Identify the Quantum Wave Model features
Explains quantization by treating orbiting electrons as de Broglie standing waves around the nucleus.
Orbits are stable only when an integral number of electron wavelengths fit along the orbital circumference.

Anahtar Kavram

Characteristics and experimental foundations of atomic models
Soru 2Soru

In a hydrogen atom modeled according to Bohr's postulates, an electron undergoes a transition from an initial excited state nn to the ground state n=1n=1, emitting a photon whose wavelength is λ=1615R\lambda = \frac{16}{15R}, where RR is the Rydberg constant. What is the orbital angular momentum of the electron in its initial excited state prior to the transition?

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Cevap: 2hπ\frac{2h}{\pi}

Cevap

2hπ\frac{2h}{\pi}
Using the Rydberg formula 1λ=R(1121n2)\frac{1}{\lambda} = R \left( \frac{1}{1^2} - \frac{1}{n^2} \right) with λ=1615R\lambda = \frac{16}{15R}, we find 1516=11n2\frac{15}{16} = 1 - \frac{1}{n^2}, which gives n=4n = 4. By Bohr's angular momentum quantization condition, L=nh2π=4h2π=2hπL = \frac{nh}{2\pi} = \frac{4h}{2\pi} = \frac{2h}{\pi}.

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1
Apply the Rydberg formula for hydrogen to determine the principal quantum number nn of the initial state.
1λ=R(1121n2)    15R16=R(11n2)    11n2=1516    1n2=116    n=4\frac{1}{\lambda} = R \left( \frac{1}{1^2} - \frac{1}{n^2} \right) \implies \frac{15R}{16} = R \left( 1 - \frac{1}{n^2} \right) \implies 1 - \frac{1}{n^2} = \frac{15}{16} \implies \frac{1}{n^2} = \frac{1}{16} \implies n = 4.
The Rydberg formula links the photon wavelength emitted during a transition between energy levels to the principal quantum numbers.
2
Calculate the orbital angular momentum LL for n=4n=4 using Bohr's quantization condition.
L=nh2π=4h2π=2hπL = \frac{n h}{2\pi} = \frac{4 h}{2\pi} = \frac{2 h}{\pi}.
Bohr's quantization postulate dictates that orbital angular momentum is an integral multiple of h2π\frac{h}{2\pi}.

Anahtar Kavram

Bohr's Atomic Model: Spectral transitions and angular momentum quantization
Tahmini Süre:2m 0s
Soru 3Soru

During Rutherford's alpha particle scattering experiment, the vast majority of alpha particles passed straight through the gold foil with little to no deflection. What conclusion about atomic structure was drawn directly from this specific observation?

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Cevap: The atom consists mostly of empty space

Cevap

The atom consists mostly of empty space
In Rutherford's alpha particle scattering experiment, the fact that over 99% of alpha particles passed straight through the foil undeflected indicates that they encountered no massive positive obstacle. This directly proved that the volume of an atom consists predominantly of empty space, with positive charge concentrated in a tiny central region called the nucleus.

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1
Analyze the experimental observation from Rutherford's experiment
The vast majority of positively charged alpha particles suffered no deflection when passing through gold foil.
Deflection occurs when alpha particles pass close to a dense positive charge.
2
Deduce the physical implication for the structure of the atom
Since almost no deflection occurred for most particles, they encountered no heavy concentration of positive charge or mass in their path.
This proves that the dense positively charged nucleus occupies an extremely small fraction of the total atomic volume, leaving the rest as empty space.

Anahtar Kavram

Rutherford's Alpha Scattering Experiment and Nuclear Atom Model
Soru 4Soru

Match each historical atomic model on the left with its defining postulate, experimental outcome, or theoretical limitation on the right.

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Öğeler

Thomson's Plum Pudding Model
Rutherford's Planetary Model
Bohr's Quantized Model
Sommerfeld's Extension

Eşleşmeler

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Cevap

Thomson's model matches the diffuse positive sphere disproved by alpha particle backscattering; Rutherford's model matches the dense nucleus with classical radiation collapse limitations; Bohr's model matches quantized angular momentum in non-radiating orbits; Sommerfeld's extension matches elliptical sub-shells and relativistic adjustments for fine-structure splitting.
Each model directly maps to its defining theoretical contribution or failure mechanism: Thomson's diffuse charge sphere failed under α\alpha-particle scattering; Rutherford's nuclear atom suffered from classical radiation instability; Bohr's model introduced angular momentum quantization L=nL = n\hbar; and Sommerfeld's model extended orbits to ellipses with relativistic velocity corrections to account for fine structure.

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1
Analyze Thomson's Plum Pudding Model
Thomson proposed electrons embedded in a sea of positive charge. This continuous distribution could not account for α\alpha-particles rebounding at angles greater than 9090^\circ.
Identify the historical assumption and experimental contradiction for Thomson's model.
2
Analyze Rutherford's Planetary Model
Rutherford deduced a concentrated positive core (nucleus). However, according to Maxwellian electrodynamics, orbiting electrons accelerate continuously, radiating energy until collapsing into the nucleus.
Identify the primary theoretical failure of classical planetary electron orbits.
3
Analyze Bohr's Quantized Model
Bohr introduced the non-classical postulate that electrons exist in stable stationary states with angular momentum L=nh2πL = \frac{nh}{2\pi}, accurately yielding the Rydberg formula for hydrogen.
Recognize the quantum postulate resolving Rutherford's radiation collapse.
4
Analyze Sommerfeld's Extension
To explain fine spectral line splitting not accounted for by circular Bohr orbits, Sommerfeld introduced elliptical orbits with azimuthal quantum numbers and relativistic mass variation at high electron velocities.
Connect fine-structure spectral features to relativistic elliptical orbital modifications.

Anahtar Kavram

Development and Limitations of Historical Atomic Models
Soru 5Soru

In a hydrogen atom modeled according to Bohr's theory, an electron undergoes a transition from an excited state with an energy of 1.51 eV-1.51\text{ eV} to a lower energy state of 3.40 eV-3.40\text{ eV}. Calculate the energy of the emitted photon in electron-volts (eV\text{eV}).

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Cevap: 1.89

Cevap

The energy of the emitted photon is 1.89 eV1.89\text{ eV}.
According to Bohr's atomic model, when an electron drops from an initial higher energy level EiE_i to a final lower energy level EfE_f, a photon is emitted carrying energy E=EiEfE = E_i - E_f. Substituting the given values gives E=1.51 eV(3.40 eV)=1.89 eVE = -1.51\text{ eV} - (-3.40\text{ eV}) = 1.89\text{ eV}.

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1
Identify the initial and final energy states of the electron.
Ei=1.51 eVE_i = -1.51\text{ eV} and Ef=3.40 eVE_f = -3.40\text{ eV}.
The electron moves from a higher (less negative) energy state to a lower (more negative) energy state.
2
Apply Bohr's energy quantization formula for photon emission Ephoton=EiEfE_{\text{photon}} = E_i - E_f.
Ephoton=1.51(3.40)=1.89 eVE_{\text{photon}} = -1.51 - (-3.40) = 1.89\text{ eV}.
By energy conservation, the energy lost by the transitioning electron equals the energy of the emitted photon.

Anahtar Kavram

Bohr's Energy Transition Postulate
Tahmini Süre:1m 0s
Soru 6Soru

In J. J. Thomson's plum pudding model of the atom, how is the positive charge distributed throughout the atom?

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Cevap: It is uniformly spread throughout a spherical volume containing embedded electrons.

Cevap

The positive charge is uniformly spread throughout a spherical volume containing embedded electrons.
In J. J. Thomson's plum pudding model, the atom is envisioned as a continuous sphere of positive charge within which negatively charged electrons are embedded evenly to maintain overall electrical neutrality.

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1
Recall the fundamental proposal of Thomson's atomic model (1897).
J. J. Thomson envisioned the atom as a sphere of positive electrification.
This accounted for atomic neutrality following his discovery of the electron.
2
Identify the arrangement of electrons within this positive sphere.
Electrons were thought to be embedded throughout the positive sphere like plums in a pudding.
This balanced the positive charge uniformly across the atomic volume.

Anahtar Kavram

Thomson's Plum Pudding Atomic Model
Tahmini Süre:45s
Soru 7Soru

In Bohr's model of the hydrogen atom, the radius of a stationary orbit is proportional to n2n^2, where nn is the principal quantum number. If the radius of the ground-state orbit (n=1n = 1) is r1r_1, what is the radius of the orbit corresponding to the second excited state?

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Cevap: 9r19r_1

Cevap

The radius of the electron's orbit in the second excited state is 9r19r_1.
In Bohr's atomic model, the ground state corresponds to the quantum number n=1n = 1. The excited states are numbered sequentially above the ground state: the first excited state is n=2n = 2 and the second excited state is n=3n = 3. Since the orbital radius scales with the square of the principal quantum number (rn=n2r1r_n = n^2 r_1), substituting n=3n = 3 yields r3=32r1=9r1r_3 = 3^2 r_1 = 9r_1. Thus, the option stating 9r19r_1 is correct.

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1
Identify the principal quantum number nn for the second excited state.
n=3n = 3
The ground state corresponds to n=1n = 1, the first excited state corresponds to n=2n = 2, and the second excited state corresponds to n=3n = 3.
2
Apply Bohr's radius formula for hydrogen-like atoms.
rn=n2r1r_n = n^2 r_1
According to Bohr's postulates, the orbital radius is proportional to the square of the principal quantum number nn.
3
Calculate r3r_3 by substituting n=3n = 3 into the radius expression.
r3=32r1=9r1r_3 = 3^2 r_1 = 9r_1
Squaring n=3n = 3 gives 99, making the radius 9 times the ground-state radius.

Anahtar Kavram

Bohr's quantization of orbital radius (rnn2r_n \propto n^2)
Tahmini Süre:1m 0s
Soru 8Soru

Historical developments in atomic physics led to several distinct models of atomic structure. Match each atomic model on the left with its defining structural feature or experimental basis on the right.

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Öğeler

Thomson's Model
Rutherford's Model
Bohr's Model
Quantum Mechanical Model

Eşleşmeler

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Cevap

Thomson's Model matches with embedded electrons in a positive sphere; Rutherford's Model matches with a dense positive nucleus from alpha scattering; Bohr's Model matches with quantized non-radiating orbits; Quantum Mechanical Model matches with electron probability orbitals.
Each historical atomic model is correctly matched to its fundamental feature: Thomson proposed electrons suspended in positive mass; Rutherford used alpha scattering to discover the compact nucleus; Bohr quantized electron orbits to explain spectral lines; and the Quantum Mechanical Model represents electrons via three-dimensional probability orbitals.

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1
Identify Thomson's contribution
Thomson proposed the 'plum pudding' model where negative electrons are embedded inside a uniform positive charge sphere.
This preceded the discovery of the atomic nucleus.
2
Identify Rutherford's contribution
Rutherford discovered the central positive nucleus through the alpha particle deflection experiment.
Large deflections meant most atomic mass and positive charge concentrated at a tiny core.
3
Identify Bohr's contribution
Bohr added quantum conditions to planetary orbits so electrons remain stable without continuously radiating energy.
Quantized angular momentum explains discrete emission line spectra.
4
Identify the Quantum Mechanical Model contribution
Modern quantum mechanics replaces fixed circular orbits with wave functions and 3D probability clouds (orbitals).
Heisenberg's uncertainty principle rules out precise circular orbits.

Anahtar Kavram

Evolution of Atomic Models
Soru 9Soru

According to Bohr's atomic model of the hydrogen atom, what condition must be satisfied by an electron moving in a stable stationary orbit?

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Cevap: Its orbital angular momentum is an integral multiple of h2π\frac{h}{2\pi}.

Cevap

An electron moves in a stable stationary orbit when its orbital angular momentum is an integral multiple of h2π\frac{h}{2\pi}.
Bohr's fundamental postulate states that an electron can revolve around the nucleus only in certain non-radiating orbits (stationary states) where its orbital angular momentum is an integral multiple of h2π\frac{h}{2\pi}.

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1
Recall Bohr's postulates for the hydrogen atom
Identify that stable orbits require quantization of orbital angular momentum.
Bohr introduced quantization to explain why orbiting electrons do not continuously emit radiation and collapse into the nucleus.
2
State the mathematical formula for angular momentum quantization
L=mvr=nh2πL = mvr = \frac{nh}{2\pi}, where nn is an integer (1,2,3,1, 2, 3, \dots) and hh is Planck's constant.
Only specific discreet orbits meeting this condition are allowed stationary states.

Anahtar Kavram

Quantization of Angular Momentum in Bohr's Model
Tahmini Süre:45s
Soru 10Soru

In Bohr's atomic model of the hydrogen atom, the radius of the ground state orbit (n=1n = 1) is 0.053 nm0.053\text{ nm}. According to de Broglie's condition for stationary electron orbits, what is the de Broglie wavelength of the electron in its second excited state? Express your answer in nanometers (nm\text{nm}).

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Cevap: 1

Cevap

The de Broglie wavelength of the electron in its second excited state is 1.00 nm1.00\text{ nm}.
The second excited state corresponds to the quantum number n=3n = 3. According to Bohr's atomic model, the radius of the nn-th orbit is given by rn=n2r1r_n = n^2 r_1, yielding r3=32×0.053 nm=0.477 nmr_3 = 3^2 \times 0.053\text{ nm} = 0.477\text{ nm}. De Broglie explained Bohr's angular momentum quantization by showing that an integral number of electron matter-waves must fit around the orbital circumference: 2πrn=nλn2\pi r_n = n \lambda_n. Solving for λ3\lambda_3 gives λ3=2πr33=2π×3×0.053 nm1.00 nm\lambda_3 = \frac{2\pi r_3}{3} = 2\pi \times 3 \times 0.053\text{ nm} \approx 1.00\text{ nm}.

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1
Identify the principal quantum number for the specified energy state
n=3n = 3
The ground state corresponds to n=1n = 1, the first excited state to n=2n = 2, and the second excited state to n=3n = 3.
2
Calculate the radius of the third stationary orbit
r3=0.477 nmr_3 = 0.477\text{ nm}
In Bohr's model, the radius of the nn-th orbit is proportional to n2n^2, so r3=32×0.053 nm=9×0.053 nm=0.477 nmr_3 = 3^2 \times 0.053\text{ nm} = 9 \times 0.053\text{ nm} = 0.477\text{ nm}.
3
Apply de Broglie's standing wave condition for stationary orbits
λ3=2πr33\lambda_3 = \frac{2\pi r_3}{3}
De Broglie postulated that a stationary orbit contains an integral number of electron de Broglie wavelengths around its circumference: 2πrn=nλn2\pi r_n = n \lambda_n.
4
Substitute values to compute the wavelength
λ3=1.00 nm\lambda_3 = 1.00\text{ nm}
λ3=2×3.1416×0.477 nm3=2π×3×0.053 nm0.9992 nm1.00 nm\lambda_3 = \frac{2 \times 3.1416 \times 0.477\text{ nm}}{3} = 2\pi \times 3 \times 0.053\text{ nm} \approx 0.9992\text{ nm} \approx 1.00\text{ nm}.

Anahtar Kavram

De Broglie Standing Wave Quantization in Bohr Atomic Model
Soru 11Soru

During a head-on collision in Rutherford's α\alpha-particle scattering experiment, an α\alpha-particle of initial speed vv approaches a stationary heavy nucleus. The distance of closest approach achieved by the α\alpha-particle is r0r_0. If the initial speed of the α\alpha-particle is increased to 2v2v, what will be the new distance of closest approach in terms of r0r_0?

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Cevap: r04\frac{r_0}{4}

Cevap

The new distance of closest approach will be r04\frac{r_0}{4}.
At the distance of closest approach, the entire initial kinetic energy of the α\alpha-particle is converted into electric potential energy: Ek=12mv2=keq1q2rE_k = \frac{1}{2}mv^2 = \frac{k_e q_1 q_2}{r}. Rearranging for rr gives r=2keq1q2mv2r = \frac{2k_e q_1 q_2}{m v^2}, showing that rr is inversely proportional to v2v^2. When the initial speed is doubled to 2v2v, the kinetic energy increases by a factor of 22=42^2 = 4. Consequently, the distance of closest approach is reduced to one-fourth of its initial value, r04\frac{r_0}{4}.

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1
Apply conservation of mechanical energy at the distance of closest approach.
Initial kinetic energy equals electrostatic potential energy at distance r0r_0: 12mv2=14πε0q1q2r0\frac{1}{2} m v^2 = \frac{1}{4\pi\varepsilon_0} \frac{q_1 q_2}{r_0}.
At the distance of closest approach, the α\alpha-particle momentarily stops, converting all kinetic energy into electric potential energy.
2
Express the distance of closest approach r0r_0 in terms of initial speed vv.
r0=2q1q24πε0mv21v2r_0 = \frac{2 q_1 q_2}{4\pi\varepsilon_0 m v^2} \propto \frac{1}{v^2}.
Rearranging the energy conservation equation demonstrates that distance of closest approach is inversely proportional to v2v^2.
3
Substitute the new speed v=2vv' = 2v into the proportion.
r1(2v)2=14v2=r04r' \propto \frac{1}{(2v)^2} = \frac{1}{4v^2} = \frac{r_0}{4}.
Doubling the speed quadruples the kinetic energy, reducing the distance required to bring the particle to rest by a factor of 4.

Anahtar Kavram

Distance of Closest Approach in Rutherford Scattering
Tahmini Süre:2m 0s
Soru 12Soru

According to Bohr's model of the hydrogen atom, the total energy of an electron in the first excited state (n=2n = 2) is 3.40 eV-3.40\text{ eV}. Calculate the electric potential energy of the electron in this state, in electron-volts (eV\text{eV}).

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Cevap: -6.8

Cevap

The electric potential energy of the electron in the first excited state is 6.80 eV-6.80\text{ eV}.
In Bohr's model of the hydrogen atom, an electron held in a circular orbit by electrostatic attraction has a kinetic energy K=EK = -E and an electric potential energy U=2EU = 2E. Given a total energy E=3.40 eVE = -3.40\text{ eV}, multiplying by 2 yields U=6.80 eVU = -6.80\text{ eV}.

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1
Identify the relationship between total energy and electric potential energy in the Bohr atomic model.
U=2EU = 2E, where UU is potential energy and EE is total energy.
For an inverse-square electrostatic force binding an electron in a circular orbit, the virial theorem dictates that kinetic energy K=EK = -E and potential energy U=2EU = 2E.
2
Substitute the given value of total energy E=3.40 eVE = -3.40\text{ eV} to solve for UU.
U=2×(3.40 eV)=6.80 eVU = 2 \times (-3.40\text{ eV}) = -6.80\text{ eV}.
Direct multiplication yields the exact electric potential energy of the bound electron.

Anahtar Kavram

Energy components (kinetic, potential, and total energy) of an electron in Bohr's atomic model
Soru 13Soru

In Rutherford's α\alpha-particle scattering experiment, most of the α\alpha-particles passed straight through the gold foil with negligible deflection, while a very small fraction was scattered through angles greater than 9090^\circ. Which fundamental deduction about atomic structure was directly established by these rare, large-angle scatterings?

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Cevap: The positive charge and nearly all the atomic mass are concentrated in an extremely small, dense central region called the nucleus.

Cevap

The positive charge and nearly all the atomic mass are concentrated in an extremely small, dense central region called the nucleus.
Large-angle deflection (>90>90^\circ) requires an immense repulsive Coulomb force, which can only occur if the entire positive charge and virtually all atomic mass are concentrated in a tiny central region (the nucleus). If positive charge were spread out over the entire atomic volume, the maximum electric field would be far too weak to turn back high-velocity alpha particles.

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1
Analyze the experimental observations from Rutherford's alpha-scattering experiment.
Most α\alpha-particles pass undeflected (indicating mostly empty space), while a tiny fraction scatter at angles >90>90^\circ.
Understanding the physical cause of large-angle electrostatic deflection.
2
Relate electrostatic repulsive force to mass and charge distribution.
To turn around a fast-moving positive α\alpha-particle (He2+He^{2+}), it must experience a intense Coulomb repulsion F=14πε0q1q2r2F = \frac{1}{4\pi\varepsilon_0}\frac{q_1 q_2}{r^2} at very small distance rr.
A diffuse charge distribution (Thomson model) yields weak electric fields that cannot cause wide-angle scattering.
3
Identify the structural conclusion drawn by Rutherford.
The entire positive charge and mass must reside in a massive, concentrated center (the nucleus).
Directly matches the core physical takeaway of the nuclear atomic model.

Anahtar Kavram

Rutherford Nuclear Model and Alpha Scattering Deduction
Soru 14Soru

In Bohr's model of the hydrogen atom, the energy of an electron in a stationary orbit with principal quantum number nn is given by En=13.6n2 eVE_n = -\frac{13.6}{n^2}\text{ eV}. What is the frequency of the photon emitted when an electron transitions from the n=4n = 4 energy state to the n=2n = 2 energy state? (h=6.63×1034 Jsh = 6.63 \times 10^{-34}\text{ J}\cdot\text{s}, 1 eV=1.6×1019 J1\text{ eV} = 1.6 \times 10^{-19}\text{ J})

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Cevap: 6.15×1014 Hz6.15 \times 10^{14}\text{ Hz}

Cevap

6.15×1014 Hz6.15 \times 10^{14}\text{ Hz}
The energy of the emitted photon corresponds to the difference between the initial energy level (n=4n = 4) and the final energy level (n=2n = 2), giving ΔE=0.85 eV(3.40 eV)=2.55 eV\Delta E = -0.85\text{ eV} - (-3.40\text{ eV}) = 2.55\text{ eV}. Converting 2.55 eV2.55\text{ eV} to Joules yields 4.08×1019 J4.08 \times 10^{-19}\text{ J}. Dividing this energy by Planck's constant (6.63×1034 Js6.63 \times 10^{-34}\text{ J}\cdot\text{s}) produces a photon frequency of 6.15×1014 Hz6.15 \times 10^{14}\text{ Hz}.

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1
Calculate the energy levels for n=4n = 4 and n=2n = 2
E4=13.642=0.85 eVE_4 = -\frac{13.6}{4^2} = -0.85\text{ eV} and E2=13.622=3.40 eVE_2 = -\frac{13.6}{2^2} = -3.40\text{ eV}
Electron energy in Bohr's model depends inversely on the square of the principal quantum number.
2
Find the energy of the emitted photon
ΔE=E4E2=0.85 eV(3.40 eV)=2.55 eV\Delta E = E_4 - E_2 = -0.85\text{ eV} - (-3.40\text{ eV}) = 2.55\text{ eV}
The energy of the emitted photon equals the energy lost during the downward transition between states.
3
Convert the photon energy from electron-volts to Joules
ΔE=2.55×1.6×1019 J=4.08×1019 J\Delta E = 2.55 \times 1.6 \times 10^{-19}\text{ J} = 4.08 \times 10^{-19}\text{ J}
Energy must be converted to SI units (Joules) before applying Planck's equation.
4
Calculate the photon frequency using f=ΔEhf = \frac{\Delta E}{h}
f=4.08×1019 J6.63×1034 Js6.15×1014 Hzf = \frac{4.08 \times 10^{-19}\text{ J}}{6.63 \times 10^{-34}\text{ J}\cdot\text{s}} \approx 6.15 \times 10^{14}\text{ Hz}
Photon energy and frequency are related by the Planck relation E=hfE = h f.

Anahtar Kavram

Bohr Model Energy Transitions and Photon Frequency