Comprehensive Study Guide: Fundamentals of Atomic Structure and Electricity

Atom

The basic fundamental unit of an element and the smallest unit of matter that retains the specific chemical properties of that element.

Democritus

Ancient Greek philosopher who proposed that all matter is composed of small, indivisible particles called atomos.

Nucleus

The densely packed central core of an atom that contains protons and neutrons.

Electron Cloud

The region of mostly empty space surrounding the nucleus where electrons move continuously in orbitals.

Proton

A subatomic particle with a positive electrical charge ($+$) located inside the atomic nucleus.

Neutron

A subatomic particle carrying a neutral charge (zero charge) located inside the atomic nucleus.

Electron

A subatomic particle with a negative electrical charge ($-$) that orbits the nucleus within energy levels.

Atomic Number

The total number of protons in an atom's nucleus, which uniquely defines a chemical element.

Electricity

A form of energy resulting from the continuous movement of electric charge ($\text{Electricity} = \text{Moving Charge}$).

Electric Current

The rate of flow of electric charge through a conductive medium, measured in amperes ($A$).

Voltage

The electromotive force or electrical pressure pushing free electrons through a circuit, measured in volts ($V$).

Ohm's Law

A mathematical rule stating that current is directly proportional to voltage and inversely proportional to resistance ($V = I \times R$).

Conductor

A material containing loosely bound electrons that allows electric current to flow through easily (e.g., copper, gold).

Insulator

A material with tightly bound electrons that strongly resists the flow of electric current (e.g., rubber, glass).

Series Circuit

A circuit arrangement where components are connected sequentially in a single unbroken loop.

Parallel Circuit

A circuit arrangement where components are connected across multiple separate branches.

Direct Current (DC)

Electric current where electric charges flow continuously in a single, fixed direction.

Alternating Current (AC)

Electric current where electric charges rapidly switch and alternate direction periodically.