A Level Physics AQA

Particles: Atomic Structure

Section 1: Fundamental Particles

• Atoms are made up of three types of subatomic particles: protons, neutrons, and electrons.
• These particles can be divided into hadrons, consisting of protons and neutrons, and leptons, which are electrons.
• Quarks are even smaller particles that make up hadrons. There are six types of quarks: up, down, charm, strange, top, and bottom.
• Protons and neutrons are made up of up and down quarks.
• Antiparticles exist for all of these particles, with properties such as charge as the mirror image of those of their particles.

Section 2: Atomic Structure

• The central nucleus contains the protons and neutrons, whereas the electrons move around the nucleus in energy levels or shells.
• The atomic number (Z) of an atom is equal to the number of protons in its nucleus.
• The mass number (A) of an atom is the total number of protons and neutrons in the nucleus.
• Isotopes are variations of an element that have the same number of protons but different number of neutrons.

Section 3: Charge and Mass of Subatomic Particles

• The proton has a charge of +1 and a mass of 1 unified atomic mass unit (u).
• The neutron has no charge and a mass of approximately 1 u.
• The electron carries a charge of -1 and has a much smaller mass, approximately 1/2000 u.
• Quarks have fractional charges: Up and Charm quarks have a charge of +2/3, while Down, Strange and Bottom quarks have a -1/3 charge.

Understanding these core principles will help develop a deeper understanding of atomic structure and the role each of these particles play in the behaviour and properties of matter at the atomic level.