Chapter 12 - Atomic Structure Flashcards
What did Rutherford do and notice which led to the gold foil experiment?
He noticed most alpha particles passed straight through a thin mica sheet, suggesting that there was a large amount of empty space in the atom.
Define nuclear model of the atom?
A model of the atom in which negative charges (electrons) are distributed outside a tiny nucleus of positive charge.
Explain the gold foil experiment?
Box containing a vacuum. Thin sheet (few hundred atoms) of gold feel placed in between alpha source and detector. Detector is made of a scintillating material which flashes each time it’s struck by alpha, microscope used to see flashes. Alpha source turned on, flashes counted, when one doesn’t reach they know it must have been deflected by nucleus.
Rough radii of proton, neutron, nucleus, atom?
Proton/neutron 10^-15m
Nucleus 10^-15/-14m
Atom 10^-10m
Size of femtometre ?
10^-15m
Define nucleon?
A particle found in an atomic nucleus.
Define nucleon number?
The number of neutrons and protons in the nucleus of an atom.
Define neutron number?
The number of neutrons in the nucleus of an atom.
Define proton number?
The number of protons in the nucleus of an atom.
What is the relative atomic mass and charge of an alpha particle?
+2e
4
Define nuclide?
A specific combination of protons and neutrons in a nucleus.
What happens to the ratio of neutrons to protons as an atom gets heavier?
Ratio gets larger (more neutrons than protons).
Define isotope?
Nuclei of the same element with a different number of neutrons but the same number of protons.
Define ion?
An atom with a net positive or negative charge.
Define strong nuclear force?
A fundamental attractive force of nature that acts between quarks.
What does the strong nuclear force do?
It holds the nucleus together.
Why is the strong nuclear force required?
Because the electrostatic repulsive force is much much larger than the gravitational force between protons therefore another force is required to hold the nucleus together.
Why are there more neutrons than protons in heavier nuclei?
Because the strong nuclear force is very short ranged but the electrostatic repulsive force is long-ranged. Therefore in heavier nuclei there are more neutrons to dilute the protons.
Define hadrons?
Particles consisting of quarks such as the proton or the neutron.
Define leptons?
A group of fundamental particles that includes the electron and the neutrino.
Define quarks?
Fundamental particles that make up hadrons, such as the proton and neutron.
Name a difference between hadrons and leptons?
Hadrons are affected by the strong nuclear force but leptons are not.
What are the six types of quarks?
Up quark down quark strange quark and their antiquarks
What quarks make up a proton?
u u d
What quarks make up a neutron?
u d d
What quarks make up a phi meson?
Strange quark and an anti-strange quark.
What does the line above a quark mean?
It means it is an antiquark
What three factors do you quarks account for?
Charge (Q) Baryon number (B) Strangeness (S)
What is the quark table?
Notes
Define plum pudding model?
A model of the atom in which negative charges are distributed throughout a sphere of positive charge.
Pi+ meson make up?
u and anti d
Phi meson make up?
s and anti s
