Matter and Elementary Parti

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Radioactivity and Elementary

Particles

Introduction to Quantum Theory

Building blocks of matter

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Foundation of Quantum Theory

Critical Knowledge

Dual nature of light (waves & particles

properties)

Electromagnetic Spectrum

Spectral Analysis

Rutherfords Model of Atom

Radioactivity

Photoelectric effect

Light

EM Spectrum

Photons?

Radiation

PhotoelectricEffect

Atom Model

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electrons, negatively charged particles (quantum states).

protons, the heavy positive nucleus of the hydrogen atom

nuclei, positively charged

1932: Chadwick observes a penetrating neutral radiationproduced in the collision of alpha particles with berylium, theneutron, whose mass is close to that of the proton.

All elements are composed of three constituents, electrons, protons andneutrons.Photon (the quantum of electromagnetic radiation) is produced when

electrons change states in the atom.

A given element is defined in terms of how many electrons (whichequals the number of protons) it has. Different isotopescorrespond to different numbers of neutrons in the nucleus.

http://online.physics.uiuc.edu/courses/phys150/fall03/

Constituents of the Atom

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Subatomic Particles:

Charge Mass Location

Protons Positive 1.0073 amu Nucleus

Neutrons Neutral 1.0087 amu Nucleus

Electron Negative 0.000549 amu Electron Cloud

http://en.wikipedia.org/wiki/Particle_physics

number of protons in an atom =atomic number

number of neutrons in an atom =mass number - atomic number

2He4

Atomicnumber

Atomicmass

Composite

particles

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Subatomic particles Proton

-

subatomic particle with positive charge e+. The mass

of the proton is 1,836 times the mass of the electron. Protons

are made up of quarks. Proton was discovered as a product

of the disintegration of the atomic nucleus. Proton belongs to

a class of baryons which are made up of three quarks. Proton

is also a hadron (strong forces particles).

Neutron

-

subatomic particle in the baryon family.

Neutron was discovered by

James Chadwick in 1932.

The neutron is made up of quarks.

nucleons

up quarkdown quark

electron

proton

neutrons

atom

neutrino

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Elementary Particles

fundamental particles: leptons, quarks,

gauge bosons (force carriers).

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Elementary Particles

http://www.fnal.gov/pub/hep_descript.html

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Standard Model four fundamental forces of nature:

gravitational force, strong, weak, electromagnetic forces;

the gravitational force is carried by the hypothetical graviton;

the electromagnetic force is carried by the photon;

the strong interaction (holds the atomic nucleus together) is carried bygluons;

the weak interaction (radioactivity and particle decay) is carried by the Zand W particles.

Gravitational force All particles

Electromagneticforce

Charged particles:

Electron, proton, muon

Strongforce

Quarks to formprotons, neutrons

Weak

forceDecay of

heavy particles

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Standard Model Particles transmit forces between them by

exchanging force-carrying particles bosons.

Gluon g carries the strong force; it glues quarkstogether.

Photon carries the electromagnetic force; (alsotransmits light).

W and Z bosons represent the weak force;(different types of decays).

Discovery of elementary particles and development of StandardModel

Fermilabs Slide Show on Building Blocks of Nature