# Free Electrons: Causes of Release Explained

• StrawberryElf
In summary, electrons can become free by either overcoming an energy barrier or tunneling through one.
StrawberryElf
So, as far as I know free electrons are just electrons that have been 'released' from the shell of an atom and can now move. If this is true, what is it that causes the electron to become free in the first place?

StrawberryElf said:
So, as far as I know free electrons are just electrons that have been 'released' from the shell of an atom and can now move. If this is true, what is it that causes the electron to become free in the first place?

https://en.wikipedia.org/wiki/Free_electron_model

Also look at
https://en.wikipedia.org/wiki/Electronic_band_structure

An atom has discrete energy levels. A large molecule has many more energy levels, since there are many degrees of freedom. When there are many energy levels close to each other, they form a band. Electrons can easily move between states in a band.

I guess a truly free electron is a mathematical approximation.

Khashishi said:
Also look at
https://en.wikipedia.org/wiki/Electronic_band_structure

An atom has discrete energy levels. A large molecule has many more energy levels, since there are many degrees of freedom. When there are many energy levels close to each other, they form a band. Electrons can easily move between states in a band.

So, say you have a block of Copper, the free electrons are just jumping from shell to shell of the atoms that make up that copper??

The outer electrons orbit the entire molecule as a whole, I think.

StrawberryElf said:
So, say you have a block of Copper, the free electrons are just jumping from shell to shell of the atoms that make up that copper??

Assuming you're referring to free electrons as the valence electrons in a metallic object, then they occupy states in which they are shared with the entire block of copper. They no longer occupy an orbital around a single nucleus.

Dale
StrawberryElf said:
So, as far as I know free electrons are just electrons that have been 'released' from the shell of an atom and can now move. If this is true, what is it that causes the electron to become free in the first place?

In a solid, there are stuff that can't be found in isolated atoms, such as energy BANDS. At the simplest level, these are what caused a solid to be a conductor, semiconductor, insulator, etc. The conduction electrons do not belong to any particular atom. So in a photoelectric effect, the electrons being released from the solid are not "... electrons that have been 'released' from the shell of an atom...".

This is why Solid State Physics is different than atomic physics or molecular physics.

Electron emission can be as simple as having enough energy to overcome any attractive potential or barrier, or it can be as quantum-mechanical as tunneling through the barrier.

Zz.

Dale
ZapperZ said:

In a solid, there are stuff that can't be found in isolated atoms, such as energy BANDS. At the simplest level, these are what caused a solid to be a conductor, semiconductor, insulator, etc. The conduction electrons do not belong to any particular atom. So in a photoelectric effect, the electrons being released from the solid are not "... electrons that have been 'released' from the shell of an atom...".

This is why Solid State Physics is different than atomic physics or molecular physics.

Electron emission can be as simple as having enough energy to overcome any attractive potential or barrier, or it can be as quantum-mechanical as tunneling through the barrier.

Zz.
Wow - it's crazy how much of what I'm taught is wrong. Thanks for clearing that up for me ☺

## 1. What are free electrons?

Free electrons are negatively charged subatomic particles that are not bound to an atom or molecule. They are able to move freely within a material or substance and are responsible for the flow of electricity.

## 2. What causes the release of free electrons?

The release of free electrons can be caused by various factors such as heat, light, or electrical energy. For example, when a metal is heated, some of its electrons gain enough energy to break away from their atoms and become free.

## 3. How do free electrons contribute to electricity?

Free electrons are responsible for the flow of electricity in conductors. When an electrical potential is applied to a material, the free electrons move in a particular direction, creating a current. This flow of electrons is what we commonly refer to as electricity.

## 4. Are free electrons important in the natural world?

Yes, free electrons are essential in many natural processes. They play a crucial role in the formation of lightning, the transfer of energy in photosynthesis, and the Earth's magnetic field, among other things.

## 5. Can free electrons be controlled?

Yes, free electrons can be controlled through various methods such as adding impurities to a material to increase or decrease its conductivity, applying an external electric or magnetic field, or using semiconductors to manipulate the flow of electrons. These techniques are essential in modern technology, including computers and electronic devices.

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