Subatomic Particles – particles smaller than an atom

See reference table – Classification of matter

Ex)

Neutrino – no charge and less mass than electron!! (Travel close to speed of light!!!!)

Sun produces so many neutrinos that 70 billion neutrinos pass through every cm² (0.15 in²) of the surface of Earth every second.

Meson – mass somewhere between an electron and proton

made of a quark and an anti-quark

An electron is a lepton

Baryons - relatively larger subatomic particles

ex) Protons, neutrons and hyperons (mass greater than neutron)

Baryons are made of smaller particles called quarks (see ref.)

ex) protons, neutrons

3 quarks make up
every baryon

Ex)

A lithium atom consists of 3 protons, 4 neutrons, and 3 electrons. This atom contains a total of

a) 9 quarks and 7 leptons

b) 12 quarks and 6 leptons

c) 14 quarks and 3 leptons

d) 21 quarks and 3 leptons

d)21 quarks and 3 leptons

Each subatomic particle has an "antiparticle"

(same mass, opposite charge)

The “antiparticle” of an electron
is called a positron

Ex)

During beta decay, a neutron decays into a proton, an electron, and an electron antineutrino. During this process there is a conversion of a

n --> p + e + neutrino

(1) u quark to a d quark

(2) d quark to a meson

(3) baryon to another baryon

(4) lepton to another lepton

Answer:

(3) baryon (neutron) to another baryon (proton)

2. Which combination of quarks could produce a neutral baryon?

(1) cdt  (2) cts (3) cdb (4) cdu

Answer:

(3) cdb

charm +2/3

down -1/3

bottom -1/3

Sum = 0

3. Which combination of quarks would produce a neutral baryon?

(1) uud (2) udd (3) -u-ud (4) -udd

Answer:

(2) udd     

up: +2/3 

down -1/3

down  -1/3

(Sum = 0)

What does this symbol mean?

Anti up quark

Same size as an up,
opposite sign (-2/3)