Chemistry 2.2 Light as a particle LO8 & LO9

What are you changing when you increase the intensity?

When the intensity changes,  the number of photons increase. Because the electron are ejected at the same speed but the amount increases. 

When the photons hit the electrode what happens?

Electrons come out of the electrode, producing an electric current.

What are you changing when you change (increase) the wavelength?

When the wavelength increases from 400 nm to 700 nm, the energy of each photon decreases, and the electrons are ejected with less energy/speed. 

 

What happens to electrons when intensity increases ?

When the intensity increases, more electrons are emitted, but the energy of each photon stays the same. This happens because higher intensity means more photons are hitting the metal each second, so more electrons can be ejected. 

9. Explain why the photoelectric effect provides evidence for the quantized (or particle) nature of light.  ‘ 

 

Each photon has a specific amount of energy based on its frequency. An electron is only emitted when a photon has enough energy to remove it from the metal. Increasing the intensity adds more photons, but does not increase the energy of each photon. 

 

What is the photoelectric effect?

when light shines on a material and causes electrons to be ejected from its surface.

What is the minimum frequency needed to provide enough energy to eject electrons called?

frequency threshold

What does increasing the intensity do?

Increasing the intensity means sending more photons.

This can increase the number of electrons ejected, but it does not make each photon more energetic.

What does increasing frequency do?

Increasing frequency increases the energy of each photon.

What is Spectroscopy?

the study of how matter interacts with electromagnetic radiation.

What can atoms do in respect to spectroscopy ?

emit and absorb energy

The way an atom interacts with light provides information about its electrons.

What are quantized energy levels ?

Electrons in atoms can only have certain allowed energies.

They cannot exist at just any energy.

what is absorption?

When an electron absorbs the correct amount of energy, it can move from a lower energy level to a higher energy level. (the electron becomes excited.).

low energy + photon= high energy

What is emission?

An excited electron can return to a lower energy level.

When it does, it releases energy as a photon.

high energy = low energy + photon

What does an energy diagram represent?

An energy diagram represents the allowed energy levels of an atom. 3 levels

That happens to the electrons as it moves upward?

The electron absorbs energy.

What happens to the electron as it moves downward?

The electron releases energy.

Relationship between the energy levels and the photon

The larger the energy difference between two levels, the greater the energy of the photon involved.

Ranked electromagnetic fields highest to lowest

Good Xylophones Usually Vibrate In My Room