Elementary Party - Get them Sorted! Quiz

Answer: Fermions

The electron is a fermion, a group named after physicist Enrico Fermi. Electrons carry negative electric charge and help atoms form chemical bonds. They have no known smaller parts.

The key to this quiz is spin: a built-in property connected with how particles behave under rotation. Despite the name, it does not mean a particle spins like a tiny ball. Fermions have spin values such as 1/2 and 3/2, while bosons have whole-number values such as 0 and 1. An electron has spin 1/2, so it belongs with the fermions.

This difference affects how particles share space in an atom. Two electrons cannot occupy exactly the same quantum state, or complete set of allowed properties. Think of each state as a seat with room for only one electron. This rule helps explain how electrons are arranged in atoms.

Answer: Bosons

A photon is a particle of light and belongs with the bosons. This group is named in honour of Satyendra Nath Bose, whose work on light helped establish the rules for these particles. Bosons have whole-number spin, including zero; the photon's spin is 1. These numbers describe a quantum property, not how fast a particle turns.

Here is the big difference from fermions: identical bosons can share the same quantum state, meaning the same complete quantum description. Using the seating picture, many bosons can occupy the same seat. This is a comparison about their allowed quantum properties, not simply about being in the same place. A laser provides a useful example, because many photons can occupy the same light mode, or pattern of the light wave.

Photons carry the electromagnetic force, which is responsible for electric and magnetic effects. Visible light, radio waves and X-rays all consist of photons; their photons differ in energy. Photons have no electric charge and are massless.

Answer: Fermions

A proton has spin 1/2, so it belongs with the fermions. It carries positive electric charge and sits in the nucleus, the small central part of an atom. Counting the protons tells us which element we have: hydrogen has one, while carbon has six.

A proton is composite, which simply means it has smaller parts. Its three main quarks are two up quarks and one down quark. Quarks are elementary particles, and 'up' and 'down' name different types rather than directions. Gluons, the particles carrying the strong force, bind the quarks together. For this quiz, we use the spin of the whole proton, not the spin of any one part.

Answer: Bosons

A pion has spin 0, which puts it in the boson group. Zero counts as a whole number in this classification. It means the particle has no total spin angular momentum, not that it cannot move.

Pions are mesons: particles whose basic structure is a quark paired with an antiquark. An antiquark is the antimatter partner of a quark, with the same mass but opposite electric charge. Although these parts are fermions, their combined spin in a pion is zero. Pions come in positively charged, negatively charged and neutral forms, and all are bosons. They are unstable, meaning they change into other particles through a process called decay.

Answer: Fermions

A muon is rather like a much heavier cousin of the electron. It has the same negative electric charge and the same spin, 1/2, so it is also a fermion. Like the electron, it is elementary: it has no known smaller parts. Its antimatter partner, the antimuon, has positive charge and is also a fermion.

Muons are produced in showers of particles when cosmic rays, high-energy particles from space, hit Earth's atmosphere. Many reach the ground and pass through us. Unlike an electron, a muon is unstable. A negative muon usually decays into an electron, a muon neutrino and an electron antineutrino. Neutrinos are very light, electrically neutral particles that rarely interact with matter; an antineutrino is an antimatter counterpart.

Answer: Bosons

The gluon belongs with the bosons because it has spin 1. Its name suggests glue, which is a useful way to remember its job: carrying the strong force that binds quarks together inside protons and neutrons. Quarks are the smaller particles that make up those familiar parts of an atomic nucleus.

The strong force acts on a property called colour charge. Despite the name, this has nothing to do with visible colours. Just as electric charge determines how particles take part in electrical interactions, colour charge determines how they take part in strong interactions. Gluons themselves carry colour charge, so they can interact with one another too. They are elementary particles, with no known smaller parts.

Answer: Fermions

The neutron is a fermion with total spin 1/2. It has no overall electric charge and is found alongside protons in most atomic nuclei, the centres of atoms. Its three main quarks are one up quark and two down quarks. Their electric charges add up to zero.

Changing the number of neutrons does not change which element an atom is, but it does change its isotope. Isotopes are forms of the same element with different numbers of neutrons. For example, carbon-12 and carbon-14 both have six protons, but they have six and eight neutrons respectively. The neutron is composite, meaning it has smaller parts, so its classification depends on the spin of the whole particle.

Answer: Bosons

A kaon belongs with the bosons because it has spin 0. It is a meson, a particle whose basic structure pairs a quark with an antiquark. The antiquark is an antimatter partner of a quark. Kaons contain a strange quark or a strange antiquark; 'strange' is the name of a type of quark, not a description of odd behaviour.

Kaons have more mass than pions, the lighter mesons elsewhere in this quiz. There are charged and neutral kaons, but all belong in the same boson group. They are unstable and decay into other particles. Their charge and lifetime can differ; their whole-number spin is what matters for this sorting task.

Answer: Fermions

A neutrino has spin 1/2, so it belongs with the fermions. It has no electric charge and only a very small mass. Neutrinos rarely interact with ordinary matter, which is why enormous numbers can pass through your body without you noticing.

The Sun produces neutrinos during nuclear fusion, the process in which light atomic nuclei join to form heavier ones and release energy. The three established neutrino types are called electron, muon and tau neutrinos. These names link them to three related particles; they do not mean that a neutrino contains an electron, muon or tau. All three types are fermions, so the general name 'neutrino' gives a definite answer here.

Answer: Bosons

The eta particle is a boson with spin 0 and no electric charge. Eta is the name of the Greek letter used for its symbol. Like the pion and kaon, it is a meson: a composite particle described in terms of a quark and an antiquark. These are smaller constituents, so the eta is not an elementary particle.

It is heavier than a pion and exists only briefly before decaying into other particles. One possible decay produces two photons, the particles of light. This gives us a useful final example: being electrically neutral does not decide whether something is a boson or a fermion. The neutral eta is a boson, while the neutral neutron is a fermion, because their spins differ.