IB Physics Topic E.1.2 Evidence from Atomic Spectra Revision Notes (SL/HL)

IB Physics Topic E.1.2 Evidence from Atomic Spectra Revision Notes (SL/HL) | RevisionDojo

Written by official IB examiners

Light Emission: Electrons Transitioning to Lower Energy Levels

Think about a hydrogen atom: it consists of a single electron orbiting a positively charged nucleus (a proton).
Within the atom, the electron can only exist in specific energy levels, which are quantized.
This means the electron cannot possess an arbitrary amount of energy, it must "choose" from a discrete set of allowed energy levels.

How Does Light Emerge?

When an electron transitions from a higher energy level to a lower one, it releases energy in the form of light.

This light is emitted as a photon.

Definition

Photon

A photon is a tiny particle that comprises waves of electromagnetic radiation.

A photon's energy is determined by the equation: $$E = hf$$ where:
1. $E$ is the energy of the photon,
2. $h$ is Planck’s constant, $6.63 \times 10^{-34}\,\text{J s}$.
3. $f$ is the frequency of the emitted light.
The frequency $f$ determines the color of the light.
Since the energy levels in an atom are fixed, the emitted light has specific, predictable wavelengths.
When passed through a prism or diffraction grating, this light separates into distinct lines, forming the emission spectrum.

Definition

Emission spectrum

The emission spectrum of a chemical element or chemical compound is the spectrum of frequencies of electromagnetic radiation emitted due to an atom or molecule transitioning from a high energy state to a lower energy state.

Example

An atom emits a photon when an electron drops between two energy levels separated by $\Delta E = 3.0 \, \text{eV}$.
Convert the energy to joules: $\Delta E = 3.0 \times 1.6 \times 10^{-19} = 4.8 \times 10^{-19} \, \text{J}$.
Find the wavelength from $\lambda = \frac{hc}{\Delta E} = \frac{(6.63 \times 10^{-34})(3.00 \times 10^8)}{4.8 \times 10^{-19}} = 4.1 \times 10^{-7} \, \text{m}$.
This is about $410 \, \text{nm}$, in the violet part of the visible spectrum.
A larger energy gap gives a shorter wavelength.

Nice try, unfortunately this paywall isn't as easy to bypass as you think. Want to help devleop the site? Join the team at https://revisiondojo.com/join-us. exercitation voluptate cillum ullamco excepteur sint officia do tempor Lorem irure minim Lorem elit id voluptate reprehenderit voluptate laboris in nostrud qui non Lorem nostrud laborum culpa sit occaecat reprehenderit

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Duis aute irure dolor in reprehenderit

Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit.

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

Unlock the rest of this chapter with a free account

Light Emission: Electrons Transitioning to Lower Energy Levels

Think about a hydrogen atom: it consists of a single electron orbiting a positively charged nucleus (a proton).
Within the atom, the electron can only exist in specific energy levels, which are quantized.
This means the electron cannot possess an arbitrary amount of energy, it must "choose" from a discrete set of allowed energy levels.

How Does Light Emerge?

When an electron transitions from a higher energy level to a lower one, it releases energy in the form of light.

This light is emitted as a photon.

Definition

Photon

A photon is a tiny particle that comprises waves of electromagnetic radiation.

A photon's energy is determined by the equation: $$E = hf$$ where:
1. $E$ is the energy of the photon,
2. $h$ is Planck’s constant, $6.63 \times 10^{-34}\,\text{J s}$.
3. $f$ is the frequency of the emitted light.
The frequency $f$ determines the color of the light.
Since the energy levels in an atom are fixed, the emitted light has specific, predictable wavelengths.
When passed through a prism or diffraction grating, this light separates into distinct lines, forming the emission spectrum.

Definition

Emission spectrum

Example

An atom emits a photon when an electron drops between two energy levels separated by $\Delta E = 3.0 \, \text{eV}$.
Convert the energy to joules: $\Delta E = 3.0 \times 1.6 \times 10^{-19} = 4.8 \times 10^{-19} \, \text{J}$.
Find the wavelength from $\lambda = \frac{hc}{\Delta E} = \frac{(6.63 \times 10^{-34})(3.00 \times 10^8)}{4.8 \times 10^{-19}} = 4.1 \times 10^{-7} \, \text{m}$.
This is about $410 \, \text{nm}$, in the violet part of the visible spectrum.
A larger energy gap gives a shorter wavelength.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

Topic A - Space, time and motion5 subtopics

Topic B - The particulate nature of matter5 subtopics

Topic C - Wave behaviour5 subtopics

Topic D - Fields4 subtopics

Topic E - Nuclear and quantum physics5 subtopics

IB Physics E.1.2 Evidence from Atomic Spectra Notes

Topic A - Space, time and motion5 subtopics

Topic B - The particulate nature of matter5 subtopics

Topic C - Wave behaviour5 subtopics

Topic D - Fields4 subtopics

Topic E - Nuclear and quantum physics5 subtopics

Light Emission: Electrons Transitioning to Lower Energy Levels

How Does Light Emerge?

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Light Emission: Electrons Transitioning to Lower Energy Levels

How Does Light Emerge?

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account