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Elementary particles are the building blocks of the universe. They are not made up of smaller parts. Quarks are one type of elementary particle. There are six types of quarks: up, down, charm, strange, top, and bottom.
Each type, also known as a ‘flavor’, has its own properties like mass and charge. Quarks combine in specific ways to form other particles. For example, a proton is made of two up quarks and one down quark. An electron is another type of elementary particle, but it is not made of quarks. Instead, it belongs to a different family called leptons.
Understanding the basic types of elementary particles, like quarks and electrons, helps us understand the composition and behavior of all matter.

Hadrons are particles made up of quarks. There are two main types of hadrons: baryons and mesons.

• Baryons are made of three quarks. Protons and neutrons are the most well-known baryons. They are critical for the structure of atomic nuclei.
• Mesons are made of one quark and one antiquark. Mesons are less stable than baryons and often exist only for a short time before decaying.

Hadrons interact through the strong nuclear force, which is one of the four fundamental forces in nature. This force holds quarks together inside hadrons.
Hadrons themselves can combine in different ways to form atomic nuclei, leading to the formation of elements. Understanding hadrons is key to understanding complex structures in the universe, from tiny atoms to massive stars.

Protons and neutrons are the building blocks of atomic nuclei. Together, they are known as nucleons.

• Protons are positively charged particles made of two up quarks and one down quark. They contribute to the overall charge of an atom. The number of protons in the nucleus defines the chemical element and its properties.
• Neutrons are neutral particles made of one up quark and two down quarks. They have no electric charge but play a critical role in the stability of the nucleus. Neutrons help balance the repulsive forces between positively charged protons.

Protons and neutrons bind together in the nucleus through the strong nuclear force, overcoming the repulsion between like charges. This binding energy is vital for the stability of atoms. Understanding protons and neutrons helps us explain the diversity of elements and their behaviors in chemical reactions.