Subatomic Particles
and Isotopes
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Properties of subatomic particles.
Name
Symbol
Charge
(C)
Common
Charge
Mass
(kg)
Location
Electron
e-
-1.602 x
10-19
-1
9.11 x
10-31
Outside
nucleus
Proton
p+
1.602 x
10-19
+1
1.673 x
10-27
Nucleus
Neutron
n0
0 (neutral)
0 (neutral)
1.675 x
10-27
Nucleus
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Four Basic Forces in Nature
•
There are 4 forces in nature that effect all
matter in the universe. (Remember - a force is
a push or a pull)
1. Strong Force – strongest force but has the shortest
reach. It is responsible for holding the nucleus of an
atom together.
2. Weak Force – next strongest force. It is responsible
for radioactive decay.
3. Electromagnetic Force – the force of attraction or
repulsion between charged objects or poled objects.
Most important force in the study of chemistry
4. Gravity – weakest force but has the longest reach.
It is a force of attraction between any two objects in
the universe.
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Grand Unified Force
• Shortly after the Big Bang, all 4 forces were
thought to be one force dubbed the Grand
Unified Force.
• As the universe cooled the forces began to
separate.
• Three of the 4 forces have been shown to be
part of one force.
• Even though Einstein spent the last 20+ years of
his life trying to work in gravity, it still hasn’t been
shown to be part of a Grand Unified Force.
©2011 University of Illinois Board of Trustees • http://islcs.ncsa.illinois.edu/copyright
• Rutherford Model
Other Subatomic
Particles
http://www.frca.co.uk/images/helium-anim.gif
http://www-d0.fnal.gov/public/pubs/third_generation_leptoquark_prl/constituents.gif
©2011 University of Illinois Board of Trustees • http://islcs.ncsa.illinois.edu/copyright
http://media.photobucket.com/image/proton%20and%20antiproton
%20collisions/egosumebrius/CDF-Top.jpg
http://www.particle.kth.se/SEASA/shower_arty.jpg
An artist's impression of the shower of
subatomic particles produced when a
cosmic ray proton collides with the top
of the earth's atmosphere.
Electronic signatures produced by
collisions of protons and antiprotons
in the Tevatron accelerator at
Fermilab provided evidence that the
elusive subatomic particle known as
top quark has been found.
©2011 University of Illinois Board of Trustees • http://islcs.ncsa.illinois.edu/copyright
• Quarks, photons,
gluons—physicists
understand their
characteristics, but
didn't know what they
may look like. That is
until Jan-Henrik
Andersen translated
the physical properties
of subatomic particles
to images on paper
and canvas.
http://cdn.physorg.com/newman/gfx/news/2005/TOP_EVENT.jpg
©2011 University of Illinois Board of Trustees • http://islcs.ncsa.illinois.edu/copyright
Coulomb’s Law (p. 83)
• The most important of the four forces in
chemistry is the electromagnetic forces
• Coulomb’s Law, which describes the force of
attraction or repulsion between charged objects,
is one of the most important laws in chemistry.
• Coulomb’s Law states that the force of
attraction or repulsion between charged particles
directly depends on the amount of charge on
the particles and inversely depends on the
square of the distance that separates the
particles.
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Coulomb’s Law
• The greater the charge on the particles, the
greater the force of attraction or repulsion.
– Remember – opposite charges attract and like
charges repel.
• The closer the charged particles are to each
other, great the force.
Where
• Coulomb’s law in formula form: Kc = Coulomb’s Constant
Kc = 8.9876 x 109 N m2/C2
Felectric = Kcq1q2
q1 and q2 are the charges
2
D
on the objects
D is the distance that
separates the charges.
©2011 University of Illinois Board of Trustees • http://islcs.ncsa.illinois.edu/copyright
Which has the greatest force
between the particles?
A.
B.
C.
D.
+
++
+
_
Answer: B
_
++
_
_
_
_
©2011 University of Illinois Board of Trustees • http://islcs.ncsa.illinois.edu/copyright
Atomic Number and Mass Number
• Atomic Number is the number of protons in the
nucleus.
– All atoms of the same element have the same atomic
number.
• Mass number is the number of protons plus the
number of neutrons in the nucleus.
– Atoms of the same element can have different mass
numbers because the number of neutrons can be
different.
• Atoms of the same element with different mass
numbers are called isotopes.If an isotope is
radioactive, sometimes it is referred to as a
radioisotope.
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Isotopes
• The symbol for isotopes uses the element
symbol and superscript on the left for mass
number and subscript on the left for atomic
number.
– Example:
– Sometimes the isotope is written with just the mass
number: He-3
Note mass number – atomic number = Number of neutrons
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