# Electric charge

• Electric charge is an inherent property of matter at all scales, from the subatomic to the macroscopic.
• At the subatomic level, electric charge is carried by elementary particles, such as electrons, protons, and neutrons. Electrons have a negative charge, while protons have a positive charge. Neutrons have no charge.

Electron (-)

Protons (+)

Neutron (o)

• At the atomic level, electric charge is determined by the number of protons and electrons in an atom.
• An atom with the same number of protons and electrons is electrically neutral.
• An atom with more protons than electrons is positively charged.
• An atom with more electrons than protons is negatively charged.
• At the macroscopic level, electric charge is determined by the net charge of all the atoms and molecules in an object.
• An object with a net positive charge is positively charged.
• An object with a net negative charge is negatively charged.
• Here are some examples of electric charge at different scales:
##### Subatomic
• An electron has a negative charge, and a proton has a positive charge.
• The charge of a subatomic particle cannot change. Elementary particles, such as electrons, protons, and neutrons, have a fixed charge that is determined by their intrinsic properties. For example, an electron will always have a negative charge, and a proton will always have a positive charge.
##### Atomic
• Only atoms with a net imbalance of protons and electrons have a charge. If an atom has the same number of protons and electrons, it is electrically neutral.
• The number of protons in an atom determines its element and ots atomic number, but the number of electrons can change. This is because atoms can lose or gain electrons to become ions.

• The atomic number is a unique identifier for each element, and it is listed in the periodic table. The number of electrons in an atom is determined by its electron configuration. The electron configuration is a description of how the electrons in an atom are arranged in energy levels.

• Atoms can lose or gain electrons to become ions. An ion is a charged atom. If an atom loses electrons, it becomes a positively charged ion called a cation. If an atom gains electrons, it becomes a negatively charged ion called an anion.

• A sodium atom has a net positive charge because it has more protons than electrons. A chlorine atom has a net negative charge because it has more electrons than protons.

##### Macroscopic
• A rubber balloon that has been rubbed on hair is negatively charged. A metal rod that has been rubbed with fur is positively charged.
• Electric charge plays a role in many aspects of physics, including electromagnetism, chemistry, and particle physics. It is responsible for the formation of atoms and molecules, the propagation of light, and the behaviour of magnets. Charge is also used to generate electricity.
• Charge is a quantized property, meaning that it can only exist in discrete units. The smallest unit of charge is the elementary charge, which is denoted by the symbol e. The elementary charge is approximately equal to 1.602 × 10⁻¹⁹ coulombs.
• Charge is conserved, meaning that the total amount of charge in an isolated system cannot change. This means that when charged particles interact with each other, they can either exchange charge or transfer charge, but the total amount of charge in the system remains the same.
• Here are some examples of charge in physics:
• The electrons in an atom have a negative charge, while the protons in the nucleus have a positive charge. The attraction between the oppositely charged particles holds the atom together.
• The current in an electric circuit is caused by the flow of electrons.
• A lightning bolt is a massive discharge of electricity caused by the build-up of charge in the atmosphere.
• The Northern Lights are caused by the interaction of charged particles from the Sun with the Earth’s atmosphere.
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Summary