Fundamental of Electricity

Objectives

• Define matter, element, and molecule.
• List the parts of an atom.
• Define the valence shell of an atom.
• Identify the unit for measuring current.
• Draw the symbol used to represent current in a circuit.
• Describe the difference between conductors and insulators and semiconductors.
• Define difference of potential, electromotive force, and voltage.
• Draw the symbol used to represent voltage.
• Identify the unit used to measure voltage.
• Define resistance.
• Identify characteristics of resistance i na circuit.
• Identify the unit for measuring resistance.
• Draw the symbol used to represent resistance in a circuit.

Matter

Matter is anything that occupies space and has weight.

• Matter is made up of atoms and particles like protons, neutrons, and electrons.
• It exists in different states:
  • solid,
  • liquid
  • gas
  • plasma
  • more exotic states (like Bose-Einstein condensates)

Atom

• The basic building block of matter. (Each element is made up of only one kind of atom)
• A single atom is defined by the number of protons in its nucleus.
• The number of protons determines the type of atom.
  • Example: An atom with 6 protons is a carbon atom.
  • Example: An atom with 8 protons is an oxygen atom.

Structure of an Atom

An atom has three main subatomic particles:

1. Protons ($P^+$)
   • Positively charged particles
   • Found in the nucleus (center of the atom - an area)
   • Determines the element (e.g., Hydrogen has 1 proton, Carbon has 6)
2. Neutrons ($n^0$)
   • Uncharged particles
   • Found in the nucleus
   • Adds mass and stabilizes the nucleus
3. Electrons ($e^-$)
   • ⚡Negatively charged particles
   • 💫Orbit the nucleus in the electron shells or energy levels
   • Responsible for chemical reactions and bonding

Key Properties

• 🔢Atomic number (Z): Number of protons in the nucleus. It determines the element.
• ⚖️Atomic weight (Mass number) (A): Total protons + neutrons. The mass of an atom. (just count the number)
• Isotopes: Atoms of the same element with different numbers of neutrons. (???)

info

${}^{12}_{6}\text{C}$

• 6 is the atomic number which is also the number of protons in the nucleus.
• 12 is the mass number which is also the number of protons + neutrons.

Calculation:

• Number of Protons (A, atomic number): 6
• Number of Neutrons: Mass - Atomic Number = 12 - 6 = 6
• Number of Electrons: Atomic Number - charge = 6 - 0 = 6

${}^{13}_{6}\text{C}$

Calculation:

• Number of Protons: 6
• Number of Neturons: 13 - 6 = 7
• Number of Electrons: 6 (it is an atom since it is not charged)

Electron Arrangement

Electrons occupy electron shells around the nucleus. Shells are filled in sequence.

• 1st shell: up to 2 electrons
• 2nd shell: up to 8 electrons
• 3rd shell: up to 18 electrons

This arrangement explains chemical properties and how atoms bound.

success

• Valence Shell: The outermost shell.
• Valence: The number of electrons contained in the valence shell.

Element

An element is a pure substance made of only one type of atom.

• Each element is made up of ONLY ONE kind of atom.
• Defined by the atomic number (number of protons)
• Example:
  • Carbon (C) $\to$ all atoms have 6 protons.
  • Oxygen (O) $\to$ all atoms have 8 protons.
  • Gold (Au) $\to$ all atoms have 79 protons.

success

Element could have one atom or trillions of atoms, but all of them are the same type.

Example 1: Gold jewelry 🪙

• One gold atom $\to$ a single particle with 79 protons.
• The element gold $\to$ your entire gold ring/necklace is made of trillions of gold atoms, all the same type.

Example 2: Diamond 💎

• One carbon atom $\to$ a single particle with 6 protons.
• The element carbon $\to$ a diamond is a pure carbon, but built from billions of carbon atoms linked together in a crystal structure.

Molecule

• A group of two or more atoms bounded together.
• The atoms may be of the same element or different elements.
• Examples:
  • $O_2 \to$ a molecule of oxygen (two oxygen atoms, same element).
  • $H_{2}O \to$ a molecule of water (two hydrogen atoms + one oxygen atom, different elements).

Compound

• A compound is a molecule made of atoms of different elements.
• Examples:
  • $H_{2}O \to$ hydrogen + oxygen $\to$ compound
  • $CO_2 \to$ carbon + oxygen $\to$ compound

danger

Every compound is a molecule, but not every molecule is a compound.

Conductors

Materials that contain a large number of free electrons.

If an element has 3 or less electrons in the valence shell, it might be a good conductor.

Material 🧪	Conductivity (S/m) ⚡
Silver 🥈	6.30 × 10⁷
Copper 🟠	5.96 × 10⁷
Gold 🥇	4.10 × 10⁷
Aluminum ⚪	3.77 × 10⁷
Tungsten ⚫	1.79 × 10⁷
Iron 🛠️	1.00 × 10⁷
Lead ⚙️	4.55 × 10⁶
Carbon (Graphite) 🖤	1.00 × 10⁵
Silicon (doped) 💻	1.00 × 10⁴
Glass 🔮	10⁻¹² – 10⁻¹⁰
Rubber 🟢	10⁻¹⁴ – 10⁻¹²

Insulators

Prevent the flow of electricity. Stabilized by absorbing valence electrons.

5 or more electrons in the valence shell.

Semiconductors

Can be altered to function as either as a conductor or insulator. Made out of materials with 4 electrons in the valence shell.

• Negative Ion (Anion): A negatively charged atom. (e.g., $P^{3-{}}$)
• Positive Ion (Cation): A positively charged atom. (e.g., $Mg^{2+{}}$)

info

Atom has equal number of protons and electrons. Electrical netural

Atom: ${}^{27}_{13}\text{Al}$

• protons: 13
• neturons: 27 - 13 = 14
• electrons: 13

Ion has different numbers of protons and electrons. Charged

Ion: ${}^{27}_{13}\text{Al}^{3+{}}$

• protons: 13
• neturons: 27 - 13 = 14
• electrons: atomic number - charge = 13 - (3) = 10

Current

Movement of electrons from negatively charged atoms to positively charged atoms. Represented as $I$.

Coulomb

• $6.24 \times 10^{18}$ electrons.
• Represented as $C$.

Ampere

• One coulomb moving past a single point in one second ($S$). Represented by $A$.

Potential

The ability of the source to perform electrical work.

note

Difference of potential causes electrons to move or flow in a circuit.

Voltage

The force that moves the electrons in the circuit. Represented by $V$. Unit of measure is volt.

Resistance

• Opposition to the flow of electrons. (reduce current)
• Measured in Homs.
• Represented by $\Omega$

References

• Basic Electronics Part 1 https://www.youtube.com/watch?v=nb4ovfwqup8