Aim: How can we explain the four fundamental forces and the standard model? Do Now: List all the subatomic particles that you can think of

Four Fundamental Forces Weakest Strongest Gravitational Weak nuclear Electromagnetic Strong nuclear

Gravitational Responsible for shaping the large scale structure of the universe (galaxies, stars, etc.)

Weak Nuclear Responsible for –Radioactive decay –Fusion of the sun –Conversion of neutrons into protons in the nuclei

Electromagnetic Includes electrostatic and magnetic forces

Strong Nuclear Holds the nucleus together by resisting the repulsion of protons. Very short range.

The Standard Model All matter is composed of Hadrons and Leptons

Leptons Made up of charged and neutral matter Cannot be broken down (as of now); it is a fundamental particle Experience weak force interactions

Charged Leptons electron muon tau Neutral Leptons electron neutrino muon neutrino tau neutrino

Hadrons Subatomic particles composed of quarks (the fundamental particles of the Standard Model) Experience strong force interactions

Mesons Unstable Consist of one quark and one anti-quark

Baryons Mass is equal to or greater than a proton Consists of protons and neutrons (the most common), and other types of matter

Quarks Smallest known unit of matter Cannot be isolated Exists as: –baryon (3 quarks) or –meson (quark and anti-quark)

Fundamental Rule of Standard Model: For every particle, there exists an anti- particle

Quark Types

Antiquarks Same mass, opposite charge Represented with a line on top – Represents an anti-up quark –Charge is -

Protons and Neutrons Are made of up and down quarks Proton: charge is +1 –up, up, down (uud) –(+2/3) + (+2/3) + (-1/3) = +1 Neutron: charge is 0 –up, down, down (udd) –(+2/3) + (-1/3) + (-1/3) = 0