1. By the end of this presentation, you should be able to: (a) explain that since protons and neutrons contain charged constituents called quarks they are, therefore, not fundamental particles; (b) describe a simple quark model of hadrons in terms of up, down and strange quarks and their respective antiquarks, taking into account their charge, baryon number and strangeness; (c) describe how the quark model may be extended to include the properties of charm, topness and bottomness; (d) describe the properties of neutrons and protons in terms of a simple quark model;

3. If we drew the atom to scale and made protons and neutrons a centimetre in diameter: the electrons and quarks would be less than the diameter of a hair the entire atom's diameter would be greater than the length of thirty football fields! 99.999999999999% of an atom's volume is just empty space!

5. HADRONS Mesons (consist of a quark / antiquark pair) Baryons (consist of 3 quarks; combinations of up and down quarks) protons neutrons pion kaon

6.  The original model had the first 3 quarks which were found. This model also included the corresponding antiquarks  3 more quarks were found. The heaviest were found later Quarks and their antiquarks have properties of spin (1/2 and -1/2); baron number (1/3 or -1/3) and charge according to the table on the next slide.

7. What is the charge on a neutron? u + d + d = +2/3 -1/3 – 1/3 =0 What is the charge on a proton? u + u + d = +2/3 +2/3 – 1/3 = +1 Once the charm, bottom and top quark were found, the quark model was extended as follows….

8. The symbol is the same letter, but with a bar above it. The spin is the same. The charge is the same magnitude, but with the opposite sign. The baryon numbers are all same magnitude but negative These numbers have opposite signs.