Chapter 24 - Particle Physics Flashcards
(18 cards)
What were the results of the alpha-particle scattering experiment, and what do they tell us about the structure of the atom?
-Most particles passed through the gold foil with little scattering. This suggests the atom is mostly empty space, with a point of concentrated mass (the nucleus).
-A very small number of atoms were deflected through angles of more than 90°. This suggests that the nucleus is positively charged.
Describe the simple nuclear model of the atom.
-The atom is mostly empty space.
-The nucleus is made from protons and neutrons.
-Electrons surround the nucleus.
How big is the nucleus compared to the whole atom?
The nucleus is ~10⁵ times smaller than the whole atom.
Define proton number.
The number of protons in an atom.
Define nucleon number.
The number of nucleons (protons and neutrons) in an atom.
What is the range of the strong nuclear force?
Repulsive below 0.5 femtometers, attractive at 0.5-3 femtometers. Above 3fm its effect is very small.
What do the letters R and r₀ denote in the equation R = r₀A^⅓?
R - Radius of the nucleus.
r₀ - The radius of a proton.
What is an antiparticle?
A counterpart to a regular particle, with the same rest mass but opposite charge.
What is a hadron? Give 3 examples.
A particle that is affected by the strong nuclear force. This includes quarks, protons and mesons.
What is a lepton? Give 3 examples.
A particle that is not affected by the strong nuclear force. This includes electrons, neutrinos and muons.
What is a proton made up of?
Three quarks: up, up, down.
What is a neutron made up of?
Three quarks: up, down, down.
What is a baryon?
A hadron made up of three quarks.
What is a meson?
Hadrons made with a combination of a quark and antiquark.
What force is responsible for beta decay?
The weak nuclear force.
What happens in beta minus decay?
A neutron decays into a proton, electron and antielectron neutrino.
What happens in beta plus decay?
A proton decays into a neutron, positron and electron neutrino.
What happens in beta minus and beta plus decay in terms of quarks?
-In beta minus decay, a down quark turns into an up quark.
-In beta plus decay, an up quark turns into a down quark.
