Glossary
Atoms
The basic building blocks of matter, consisting of a nucleus (protons and neutrons) surrounded by electrons. They are electrically neutral and can combine with other atoms.
Example:
When hydrogen and oxygen atoms combine, they form a water molecule, demonstrating how these fundamental units interact to create compounds.
Bottom quark
A type of quark with a fractional electric charge of -⅓e and a property called 'bottomness.' It is significantly heavier than the lighter quarks.
Example:
B mesons are particles that contain a bottom quark and are crucial for studying CP violation, a phenomenon related to matter-antimatter asymmetry.
Charm quark
A type of quark with a fractional electric charge of +⅔e and a property called 'charm.' It is heavier than up and down quarks.
Example:
The J/ψ meson, a particle discovered in 1974, is famously composed of a charm quark and an anti-charm quark.
Down quark
A type of quark with a fractional electric charge of -⅓e. It is a constituent of protons and neutrons.
Example:
A neutron is composed of two down quarks and one up quark, resulting in its neutral charge.
Electrons
Negatively charged fundamental particles that orbit the nucleus of an atom. They have a charge of -1.6 × 10⁻¹⁹ C and a very small mass of 9.11 × 10⁻³¹ kg.
Example:
The flow of electrons through a conductor is what constitutes electric current, powering our devices.
Fundamental Particles
Particles that are not composed of smaller particles and are considered the basic constituents of matter and forces. Examples include electrons, neutrinos, photons, and quarks.
Example:
Unlike protons, which are made of quarks, an electron is a fundamental particle, meaning it cannot be broken down into anything smaller.
Neutrons
Electrically neutral subatomic particles found in the nucleus of an atom. They have no charge and a mass of 1.675 × 10⁻²⁷ kg, slightly more massive than a proton.
Example:
Isotopes of an element differ in the number of neutrons in their nucleus; for instance, Carbon-12 has 6 neutrons, while Carbon-14 has 8.
Protons
Positively charged subatomic particles found in the nucleus of an atom. They have a charge of +1.6 × 10⁻¹⁹ C and a mass of 1.673 × 10⁻²⁷ kg.
Example:
The number of protons in an atom's nucleus determines its atomic number and thus its identity as a specific element, like how 6 protons make an atom carbon.
Quarks
Fundamental particles that combine to form composite particles called hadrons, such as protons and neutrons. There are six 'flavors': up, down, strange, charm, bottom, and top.
Example:
A proton is composed of two up quarks and one down quark, illustrating how these tiny particles build larger subatomic structures.
Strange quark
A type of quark with a fractional electric charge of -⅓e and a property called 'strangeness.' It is found in exotic particles like kaons.
Example:
The decay of a lambda particle often involves a strange quark transforming into an up quark, demonstrating particle transformations.
Top quark
The most massive of all known fundamental particles, with a fractional electric charge of +⅔e. It decays very quickly and is difficult to observe directly.
Example:
Discovered at Fermilab in 1995, the top quark is so massive that it's often compared to the mass of a gold atom, despite being a fundamental particle.
Up quark
A type of quark with a fractional electric charge of +⅔e. It is a constituent of protons and neutrons.
Example:
A proton contains two up quarks, contributing to its overall positive charge.