1. What is electricity?

The electric charge

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Matter is made up of atoms that can have positive or negative charges. Electricity is the presence or flow of these charged particles.

The atomic particles
The atom Ana Dapena Mora, with CANVA elements. Canva license.

Atoms contain protons, electrons, and neutrons.

  • Protons have an electrical charge of +1
  • electrons have -1
  • neutrons are neutral, they have no charge.


Protons and neutrons are in the nucleus of the atom, bound by strong forces that prevent them from separating easily. However, electrons are in the shell, the force with which they are attracted to the nucleus is much weaker and they can be transferred from one atom to another easily.

How atoms adquire their electric charge

Atoms become charged by losing or gaining electrons . If  an atom loses electrons, it becomes positively charged because it is losing negative charges (electrons). If it gains electrons, it becomes negatively charged. An atom is neutral when it contains the same number of electrons and protons.

In the figure you can see a sodium atom that has an electron in the last shell and transfer it to a chlorine atom. The sodium atom acquires a positive charge and the chlorine atom a negative charge.

A sodium atom becomes positively charged when it transfer an electron to a chlorine atom, which acquires a negative charge. CNX OpenStax and Wikimedia Commons. CC-BY-SA 4.0

The unit of charge: the Coulomb
The Coulomb . Ana Dapena Mora, with CANVA elements . Canva license .

The electron charge is: 1 e = 1.6 ·10-19 C

This amount of charge is very small. A body is made up of millions of atoms and, when it is charged, many of these atoms lose or gain electrons, and the charges we handle are much greater than that of a single electron. That is why, in the international system, a much larger amount than that of a single electron was chosen as the unit of measurement of charge:

1 C = 6.24⋅1018   e

If a body has a charge of 1 Coulomb, it means that it has gained or lost approximately 6 trillion electrons.

Audio equivalence charge electron and Coulomb:  

Comprenhension exercise. Choose the correct word

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Classify the following bodies as neutral, positive or negative.

                                                

                         (a)                                             (b)                                               (c)

(a)

(b)

(c)

Audio: 

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Calculation exercise. Fill in the gaps

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What charge does each of the bodies in the previous example have? You must indicate it with a sign followed by the numerical value of the charge, without spaces. Section (a) is used as an example.

(a) The first body has a charge of +1 because it has 8 positive charges and 7 negative charges. It has one more positive charge than it would have if it were neutral (which would be the same number of charges of each type).

(b)

(c)

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Memorization exercise. Fill in the gaps

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Read the paragraph below and complete the blank spaces with the missing words.

Matter is made up of atoms that can have positive or negative  space . space    is the presence or flow of these charged particles.     

Protons have an electrical charge of +1, space  have an electrical charge of -1, and neutrons are space  , they have no charge. space  can be transferred from one atom to another easily. .  

If an atom loses electrons, it becomes space  charged, and if it gains space  , it becomes negatively charged.  An atom is space  when it contains the same number of electrons and protons.    

In the International System, the unit of electric charge is the, space,  (C).

The electric charge of the, space,  is 1 e = 1.6 ·10-19  C. (1.6 times 10 to the power of nine Coulombs

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Learn to select information activity

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This activity is about selecting information that you find important to memorize and recording yourself reading it with your mobile phone. You can repeat this activity for all the sections of the unit. When you finish, use an audio editing app to put all the recordings together. When you are in the car, or out for a walk, listen to it, and it will help you a lot with memorizing.

Note that the texts have parts marked with color, bold or underlined to help you select the information. In this case, you could record the following:

Memorize with audios , CANVA , CANVA License
  • Electricity is the presence or flow of charged particles.
  • Proton charge = +1, electron charge = -1, neutrons are neutral. Matter is charged by the transfer of electrons. 
  • If an atom loses electrons, it becomes positively charged, and if it gains electrons, it becomes negatively charged. An atom is neutral when it contains the same number of electrons and protons.
  • In the International System of Units (SI), the unit of electric charge is the Coulomb (C).
  • The electric charge of an electron is 1 e = 1.6 10-9 C