2.3 Particles, antiparticles, and photons

• What is the smallest known constituent of matter?

  Fundamental particles
• Match the type of matter with an example:

  Solid ↔️ Ice

  Liquid ↔️ Water

  Gas ↔️ Air
• The positron is the antiparticle of the electron.


  True
• The discovery of antiparticles confirmed the existence of antimatter.

  True
• Photons are massless but carry energy and momentum
• Match the lepton with its description:

  Electron ↔️ Fundamental particle with negative charge

  Muon ↔️ Heavier version of the electron

  Neutrino ↔️ Massless lepton with no charge
• Matter has mass and occupies space
• What are fundamental particles?

  Smallest known constituents of matter
• What happens when a particle and its antiparticle meet?

  They annihilate each other
• What is the antiparticle of an electron called?

  Positron
• Photons are massless particles that carry energy
• What are the two classes of fundamental particles that constitute matter?

  Quarks and leptons
• What property distinguishes bosons from fermions?

  Spin
• What happens when a particle and its antiparticle meet in particle-antiparticle annihilation?

  Their mass converts to energy
• Photons are the carriers of electromagnetic force
• What is matter composed of?

  Fundamental particles
• What is the charge of a positron compared to an electron?

  Opposite
• Who discovered antiparticles in 1928?

  Paul Dirac
• Photons have no mass at rest
• When a particle and its antiparticle meet, they annihilate each other, converting their mass into energy
• What is the antiparticle of an electron called?

  Positron
• Steps leading to the discovery of antimatter

  1️⃣ Prediction by Paul Dirac in 1928

  2️⃣ Discovery of antiparticles
• What is the speed of light in meters per second?

  299,792,458
• Match the fundamental particles with their properties:

  Quarks ↔️ Fractions of positive or negative 1/3 and 2/3 charge

  Leptons ↔️ Integer of positive or negative 1 charge
• Bosons have half-integer spin.

  False
• Steps in particle-antiparticle annihilation

  1️⃣ A particle and its antiparticle meet

  2️⃣ They annihilate each other

  3️⃣ Their mass is converted into energy
• Photons are massless.


  True
• Matter is anything that has mass and occupies space
• Fundamental particles have internal structure.

  False
• What happens when a particle and its antiparticle meet?

  They annihilate each other
• Antiparticles were first predicted by Paul Dirac
• What fundamental particles make up light?

  Photons
• Quarks are the building blocks of protons and neutrons.


  True
• What is the charge of quarks measured in?

  Fractions of positive or negative 1/3 and 2/3
• What is matter defined as?

  Anything with mass and space
• Electrons are examples of fundamental particles

  True
• Fundamental particles have no internal structure
• Antiparticles have opposite charge
• Who first predicted the existence of antiparticles in 1928?

  Paul Dirac
• Photons travel at the speed of light

  True