Transcript Chapter 4 Notes

Chapter 4 Notes (4)
Sections 4-1,4-2
I.Development of an Atomic
Model
*Matter:
anything that has mass and volume
*Indirect Evidence:
evidence you get without actually
seeing or touching the object
-Greek Model (Democritus)
*atom:
smallest particle of an element that
has the prop of the element
~atomos:
meaning not to be
cut
-Dalton’s Atomic Theory
1. All elements are composed of
atoms
2. Atoms of the same element are
exactly alike
3. Atoms of diff. elements are
diff.
4. Compounds are formed by
joining of atoms of 2 or more
elements
II. A Divisible Atom
-Thomson’s Model:
~Plum Pudding
*Electrons: - charge
-Rutherford’s Model
~Gold Foil Experiment
~the atom was mostly empty space
with a dense, positively charged
nucleus in the center.
*Nucleus:
the center of the atom
-Bohr Model
~electrons move in definite
orbits around the nucleus
-Wave Model (Today accepted
model)
~electrons don’t move about in
a definite path
~probable location is based on
how much nrg the electron has
• SEE HISTORY OF THE ATOM
WEBSITE
•
http://hi.fi.tripod.com/timeline/
III. Subatomic Particles
*smaller than the atom
-Three main subatomic part.
1. proton
2. neutron
3. electron
**quarks (make up 1 & 2)**
-Nucleus
*center of the atom
mass (amu) charge
~proton: 1
~neutron: 1
~electron: 1/1836
+
+/-
location
nucleus
nucleus
e- cloud
*Atomic Mass Unit (amu):
measures mass of subatomic
part.
-?? Where does it come from??
-Atomic #
*number of + in the nucl
~identifies the element
~never chngs
-Isotopes
*same # of +, but diff # of
neutrons
EX:
-Mass # and Atomic Mass
*sum of the + and neutrons in
its nucleus
*Aver Atomic mass:
aver of the masses of all the
atoms in the sample.
~mass # - atomic# = #of
neutrons
III. stop
3
H
Nuclear Notation
1
Hydrogen-3
Hyphenated Notation
III. continue
-Electrons
(e-)
*e- cloud:
place in which e-’s
are likely to be found
~location depends upon how much
nrg the e- has
*nrg levels:
most likely location of the e~2,8,8.
*Valence e-:
e- outer most nrg
level
~Movement of e-’s:
-in: lose nrg
-out: gain nrg
IV. Forces Within the Atom
Video #14
-The
four forces that account for
the behavior of sub part
1. electromagnetic force
*either attract or repel particles
video #15
2. strong force
*opposes electromag force of
repulsion between +
~only when + are very close
together
weak force
*key to the power of the sun
~responsible for radioactive
decay
~ +/- ---> + and 3.
4. gravity
*weakest force known in nature
~force of attraction exerted
between all objects