Atom is the building block of matter. Atoms are very tiny to be seen by the naked eye. Atoms combine to form molecules which build the matter that we can see or touch.
To understand what electricity is, we have to get down the actual components of the atom. The atom contains three building blocks which are the protons, electrons and the neutrons. These three are found within the atom.
Protons: They are found in the nucleus, which is the heart of the atom. Thus the protons are found at the center of the atom. The protons are positively charged.
Neutrons: They are also found inside the nucleus of the atom. They are neutral; meaning that they have no charges attached to them.
Electrons: They are found in energy levels that are around the nucleus of the atom. The electrons orbit the nucleus. The number of electrons is always equal to the number of protons for an object to be termed as neutral (not charged). For example, copper has 29 protons and it has 29 electrons that orbit around the nucleus.
The electrons are the ones that are involved when it comes to electricity. Mainly the electrons that are involved are those that are at the outermost energy level. These electrons at the outermost energy level are called valence electrons and they can be easily lost from their energy level to be free.
Flow of charges (electric current)
Charge is a property of matter and it is measured in coulombs. The charge of matter can either be positive or negative. The positive charge is associated to the protons while the negative charge is associated to the electrons. The amount of negative charge of one electron is equal to the amount of positive charge in one proton. The difference in charges is brought about by the number of protons compared to the number of electrons.
To understand the flow of charges, we will have to understand the coulomb’s law which states that charges of the same type repel while charges of different types attract. Therefore electrons will be attracted to the protons. In an atom it is always very easy to dislodge an electron. However you cannot dislodge a proton from the nucleus that easily. Therefore in electricity, the electron is usually the charge carrier. But of course during our college level physics tuition classes, we learnt that holes can also be the charge carriers, especially in the case of semiconductors.
The valence electron requires very little electrostatic force for it to be made free. This can be done by either pushing it out of the energy level with another negative charge or attracting it out of its original energy level with a positive charge.
As the free electron floats in a space between atoms, it’s pulled and pushed by surrounding charges in that space. In this state of confusion, the free electron finally finds a new atom to latch on to and in doing so, the negative charge of that electron (free electron that have been attached) ejects another valence electron from the atom. This results in another electron drifting through free space looking to get attached to another atom. This produces a chain effect that continue on and on, creating a flow of electrons called electric current.