Download atomic structure

Lecture: Atomic Structure
intro to: “structure of an atom”
http://www.youtube.com/watch?v=TBrJt5LHgQ&safety_mode=true&persist_safety_mode=1&safe=active
intro to structure of an atom : “Electrons, Protons And Neutrons | Standard Model Of Particle
Physics”
http://www.youtube.com/watch?v=Vi91qyjuknM&safety_mode=true&persist_safety_mode
=1&safe=active
You will need a paper copy
of the periodic table for this
unit and its exam
Draw this:
l. Atomic structure
A. atom
1. smallest particle of an element which retains its
characteristic properties, tear aluminum foil?
2. the fundamental unit of matter (definition?)
How does this relate to the atom: ?
-building block from which all matter is made:
brick house?
3. has NO CHARGE!!!
4. based on Rutherford’s planetary model:
radioactive danger symbol:
-mostly empty space = a marble in a football
coliseum?
5. two regions: ?
a) nucleus and b) electron cloud
a. nucleus
-has two subatomic particles ?:
protons and neutrons
1. protons: + charge (battery?),
-equals the atomic #:
-which defines the element/makes it unique:
no other # on the periodic table of elements
-has 1 amu of mass: based on the average
mass of carbon’s isotopes
2. neutrons: no charge
- has 1 amu of mass
- #protons + #neutrons = atomic mass
99.999% of an atom’s mass is in the
nucleus, E=MC2 ?
Atomic # ?
# protons ?
Atomic mass ?
# neutrons ?
# + charges ?
# - charges?
3. Nuclear decay:
-occurs when the atom is not stable:
nucleus breaks apart, many types of decay
-occurs when the proton/neutron count is “off”:
meaning it varies from norm, thus unstable
-a product of the nuclear decay can be an energy
emission: radiation, or a matter emission: p or n
-Alpha decay: ejects 2 protons and 2 neutrons: ?
changes the atomic number and thus the element and
mass:
-radon gas comes from the decay of U238 
thorium  radon  lead (many of our homes in
Boulder!)
-radon is deadly in your lungs due to the mass
emissions (protons=mass!!)
-Beta decay: neutron splits into both a proton
and electronit keeps the proton (changes element, why?)
and ejecting the electron.
Mass stays same, why?
-Gamma decay: alpha and beta decay almost
always are joined by:
emitting very high frequency and high
energy waves from the electromagnetic
spectrum called gamma rays
b. electron cloud
- made of electrons moving at
almost the speed of light, thus
also called the electron cloud:
fuzzy images
- negative charge
- # electrons = # protons , why?
(right: because all atoms have no charge)
-opposite charges hold the atom together,
which particles ?
- almost no mass
6. if change # p : change ?
if change # n : change ?
if change # e : change ?
7. use your periodic table to fill in:
Pa
Ca
#p
?
?
#n
?
?
#e
?
?
amu
?
?
6. if change # p : change ?
if change # n : change ?
if change # e : change ?
7. use your periodic table to fill in:
Pa
Ca
#p
91
20
#n
140
20
#e
91
20
amu
231
40
Examples:
Iron: 26Fe56
#p, # e, at mass, # neutrons?
+1(called?): 26Fe56+1 : #e =?
Carbon: 6C12
#p, #e, at mass, # neutrons?
-1(called?): 6C12 -1 : #e =?
Potassium: 19K39
#p, #e, at mass, # neutrons?
+2 (called?): 19K39+2 : #e =?
-Bohr atom: like the planetary model, but that is actually
incorrect: e- are dynamic and w/ overlapping orbitals
1. electrons occur only at specific energy levels = n,
vacuum in between
2. e- farther from nucleus have more energy
e- held to atom by a + nucleus (opposites attract),
outer ones less so due to e- shielding
3. e- have no specific location w/in shell, only probable
occurrence: cloud-like
4. specific # e- occur in each energy level
a. maximum # per shell = 2n2 (n = shell #)
shell # 1 = ___
shell # 2 = ___
shell # 3 = ___
shell # 4 = ___
Where are shells 6 and 7 ?:
- Because of “back filling” and s,p,f,d sub shells,
incomplete filling of the energy levels (not
maximum) can vary but largely follows this format:
- Level 1 = 2
- Level 2 = 8
- Level 3 = 8
- Level 4 = 18
-When electrons become energized they
become excited and move farther away from
the nucleus
into outer energy levels:
See drawing next page:
draw this, note the axis:
-Electrons out of their normal energy level are unstable
and
release energy in the form of light then
return to their normal energy level
-The color of the light emitted depends on
which energy level they “fall back from”:
-high energy (outer): has short wave length: violets
-low energy (inner): has long wave length: reds
-Elements will emit their own different patterns of colors
called a spectrum: fire works?
-Every element has its own unique color spectrum
-The elemental color spectrum is a characteristic
property (ie: specific heat, density, solubility,
flammability, mp, bp etal)
C. Ions: charged “particle” (atom?)
1. atoms can gain or lose electrons
2. when they do they are now charged and thus
cannot be called an atom: why ?
3. same # protons as original element/atom
4. different # electrons
5. mass ?
6. + (positive) = cation: gain or lose e-?
Na+1, how many electrons?
7. - (negative) = anion: gain or lose e-?
Cl -1, how many electrons?
8. NaCl is a neutral compound because:
Na +1: lost an electron
Cl -1: gain an electron
D. Isotopes
1. not all atoms of the same element
are identical, ie dogs
2. some have a different # of neutrons,
but the atomic # (#protons) are the
same, why?
3. what is the charge?
4. thus, the atomic mass is different
5. some isotopes are unstable:
decay and emit radiation:
radioactive isotopes:
C14 decays into C12
E. Atomic behavior is very unusual and is referred to as
quantum theory:
Due to their small size, they no longer can be
explained by classic physics, instead
their values are restricted to specific amounts:
energy and momentum
F. Along the same lines as quantum theory is the
uncertainty principle:
due to its dynamic state,
subatomic particles cannot be fully observed and
described simultaneously, thus
there is a degree of uncertainty of the particles’
attributes:
time, position, energy and momentum