The Structure of Matter

Basic Particles

All matter is made up of atoms, which are themselves composed of a small number of smaller particles: protons, neutrons and electrons.
Protons and neutrons are found in the nucleus of the atom.
Electrons are much smaller and move around the edge of the atom.
Protons have a positive charge, electrons have a negative charge and neutrons have no charge.

Atomic Structure

The number of protons in an atom is referred to as the atomic number or proton number. This determines the identity of the element.
The total number of protons and neutrons in an atom is called the mass number.
Atoms can exist into different forms called isotopes, where the number of protons remains the same but neutrons vary.
Ions are essentially atoms or groups of atoms that have gained or lost electrons, thus making it charged.

Interactions of Particles

Protons and electrons are attracted to each other due to their opposing charges.
This force of attraction holds the electrons in place around the nucleus and is called the nuclear strong force.
Electron arrangement within atoms helps to determine the chemical properties of elements.
Neutrons can moderate the repulsion between protons and help stabilise the nucleus.

Quantum Model of the Atom

According to the quantum model, electrons are found in specific energy levels, or shells, around the nucleus.
Movement between these energy levels leads to emission or absorption of energy. The energy differences between the levels correspond to the frequency of light emitted or absorbed.
The number of energy levels an electron can occupy is finite, giving rise to discrete energy levels.

Antiparticles and Positrons

Every type of particle has a corresponding antiparticle with equal mass but opposite charge.
For example, the positron is the antiparticle of an electron with the same mass but a positive charge.

Fundamental Forces

There are four fundamental forces in nature: the strong nuclear force, weak nuclear force, electromagnetic force, and gravitational force.
The strong nuclear force is responsible for keeping protons and neutrons together in the nucleus. This force overcomes the electromagnetic repulsion between protons.
Weak nuclear force is responsible for radioactive decay.

Remember, understanding these basic elements and the structure of matter is key to mastering more advanced concepts in atomic, nuclear and particle physics.