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Unit 3 I,II,III(excluding Nuclear Chemistry) Test
I. Internal Atomic Structure
A. Discovery of Elementary Particles
pages 39-54
Atomic Theory
• 400 BC - Democritus – “atomos” – 4 elements earth, air, fire, and
water
• Alchemy – atoms of one element can change to another element
• Robert Boyle – element is when can longer break down substances
• Lavoisier – law of conservation of mass – mass is neither created nor
destroyed
• Proust – law of definite proportion – a given compound always
contains exactly the same proportion(%) of elements by mass
• Dalton’s Atomic Theory – be familiar with basic premises
• Some of these basic ideas were: (some are not true today)
1) All matter is made of very small, discrete particles called
atoms. (No internal structure, just solid matter)
2) All atoms of an element are alike in weight, and this weight
is different from that of any other kind of atom.
 Not true today – isotopes: have different numbers of
neutrons
3) Atoms cannot be subdivided, created, or destroyed.
 Not true today – can split atoms, they are not indivisible
4) Atoms of different elements combine in simple whole- number
ratios to form chemical compounds
5) In chemical reactions, atoms are combined, separated or
rearranged. (bonds broken and formed)
•
Dalton used his model to predict how a given pair of elements
might combine to form more than one compound. Since he
correctly predicted the formation of multiple compounds between
two elements, his atomic theory became widely accepted.
•
By the second half of the 1800s, many scientists believed that all
• Half-life- time required for half of the atoms of a radioactive
nuclide to decay.
• 5 kinds of emissions (radioactivity)
1. Alpha particles – α (Helium Nuclei)
Thomson (Plum pudding model)– discovery of electron with
cathode ray tube(meant also positive particles in atom to give
4 neutral
He charge), found charge to mass ratio for electron (is greater
2 than proton)
• Henri Becquerel – found that a piece of a mineral containing
uranium could produce its image on a photographic plate without
light. He found the source of this to be radioactivity – the
Honors
Chemistry
-Outline
NuclearbyChemistry
emission
of radiation
uranium inTest
this case. Found
• Tospontaneous
specify
which
of+the
isotopes
of
an element
we

Atoms
The
Building
Blocks
of
Matter
that atoms
4 radiation.
234 spontaneously emit
talking
about,
we use–the
symbol:charge of electron. Using
• are
Millikan
oil drop
experiment
determined
2
90
Half-liferequired
half
ofThomson,
the atoms
a radioactive
the time
charge
to mass
ratio
from
heof
found
the mass of the
A for
-31
(9.11 xZ10 kg)
nuclideelectron
to decay.
Radioactive
particles
5 kinds ofo emissions
(radioactivity)
•
Ex.
238
92 •
U
Th
He
X
•• Where • Cannot penetrate paper, skin (not large, so
1. Alpha particles – α (Helium Nuclei)
o X = the
symbol
thefar)
element
doesn’t
goof
very
o A=
the mass
number (number of protons and
4• Very
He dangerous if ingested
neutrons)
2
o Z = the atomic number (number of protons)
0 protons + number of neutrons
2. Beta
Particlesβ or of
Ex.
• Mass
number
= number
an electron
or A = Z + # of neutrons, -1
so A – Z = #- just
of neutrons
Ex. Carbon-14
(t about
life)
 Radiationγ+–5270
Highyears=half
238 3. Gamma
4energy photons w/ no mass
234 1/2

+
Ex.
14
14
02 average of the atomic
92
90 mass – the weighed
• Average atomic
 of7226
+ -1
+ element.
• masses
Rutherford’s
gold foiloccurring
experiment
(The of
nuclear
atom)0
6239
the naturally
an
4isotopes
e
90
1
0
U
He
Th
C
N
e
γ but a
Raparticles
Cc. averageo isotopic
He [4.1b]
Shot alpha
radium.
Most went through,
(atomic)
mass;from
calculations
0
88
2
few bounced
which
showed
Thomson’s
• The
atomic
mass
can
be
calculated
by that
multiplying
 •Average
+ back,
Cannot
penetrate
paper,
skin
(not
large,
so the model
1
0
was incorrect
as there
is e
arelative
small, abundance
densely packed positively
mass
ofp
each isotope
by its
n atomic
doesn’t
go
very
far)
•(expressed
Very
dangerous
charged
center(nucleus).
Predicted
existence of neutrally
1 in decimal
-1
form) and adding the results.
•
• Passes
through
wood,
skin,
humanforbody
•of one
Very
dangerous
ingested
charged
particle
inifpaper,
nucleus
to account
missing mass.
Size
carbon
atom
= 12
amu
•
Stopped
by
lead
or
several
meters
of
concrete
•*What
Chadwick
– discovered
happens
in betaneutron
emission
Positron –paper,
mass ofskin
electron, oppositely charge,
• Can4. penetrate
0
considered
anti-matter
Beta
Particlesβ orpiece
• Can2.be
stopped
by thin
of foil or wood
-1
Ex. Carbon-11
e
Ex. Carbon-14 (t1/2 about 5270 years=half life)
11
14
66
11
10
C
C


11
14
57
pn


11
01
BN
++
00
1-1
ee
np
++
00
1-1
ee
Proton became neutron plus positron
*What happens
5. Electron
capture in beta emission
• Can penetrate paper, skin
• Can be stopped
by thin piece

+ of foil or wood
o + or –
Atomic structure
 + - attract
 ++ and -- repel
• electron “e-“ is what moves to create electricity
Photoelectric
Effect – for
moreofsee
• To specify
which
thepacket
isotopes of an element we
• An experiment which provides compelling proof for the photon
are talking about, we use the symbol:
nature of light (also called the particle nature of light) is the
photoelectric effect.AIn this effect light is shone at a metal
plate, and it is found Z
that electrons are ejected. These electrons
then
get
accelerated
to a nearby plate by an external potential
• Where
difference, and a photoelectric current is established, as below.
o X = the symbol of the element
• The explanation, which was first given by Einstein and which
o Ahim
= the
theNobel
massPrize,
number
(number
of photon
protons
won
is as follows.
Each
hitsand
an
electron
in the metal, giving up its energy to the electron. This
neutrons)
can
sometimes
be enough
energy
to free the
from the
o Z = the atomic
number
(number
ofelectron
protons)
attractive forces holding it in the metal. The electron is then
• Mass
number
number
of protons
+ number
neutrons
accelerated
(or =
moves
quickly)
towards the
other side,ofcausing
oraAflow
= Zof+charges
# of neutrons,
A – Z This
= # effect,
of neutrons
and hence so
a current.
which arises
in devices such as burglar alarms, cannot be explained using a
“wave” picture of light. For example, it is found experimentally
II. Externalthat
Structure
the photoelectric
current
depends
the atomic
•Atomic
Average
atomic mass
– the
weighedcritically
average on
of the
massesofofthe
thelight
naturally
of an element.
frequency
beingoccurring
used. If isotopes
the frequency
of the light
A. Spectroscopy
pages 275-285;
3:
c. average
mass;
calculations
[4.1b]
used
is tooisotopic
low, then(atomic)
no current
is observed.
Red
light isappendix
the
A16-A19 lowest
• Thefrequency
Average atomic
mass
canisbe
calculated
by multiplying
light and
violent
the
highest frequency
light the
atomic
mass
ofEinstein
each isotope
by its
relative
abundance
• Photoelectric
effectsaid light
must
be quantized
in the
visible
spectrum.
(expressed
in
decimal
form)
and
adding
the
• Important conclusions from the work of Einstein results.
and Planck:
• Size
one carbon
atom = 12It amu
1. ofEnergy
is quantized.
can occur in only discrete
amounts of quantum. (quantum mechanics)
2. Light has characteristics of both waves and particles
(called photons). The phenomenon is sometimes
referred to as the dual nature of light.
X
•
•
•
•
•
Einstein used monochromatic light
A minimum frequency is required in order to produce a
current
o Current = flow of electrons
Einstein – light travels in bundles/packets of energy called
photon
Energy=constant time frequency of light
Einstein single handedly advanced science 50 years at the
time
Flame Test (Lab)
• Electrons in ground state are at the lowest energy state
• Excited state
• When come down to ground state, unique color is produced
• On test: If gave ROYGBIV – Where is the longest wave
length? – Red, Shortest - Violet
B.b.The
Bohr Atom
285-290
Faraday
and electrolysis
C.the
Wave
of Electrons
290-299
In
early Nature
1830s, Michael
Faraday discovered that water
solutions of
certain
substances
conduct
an electric
current. He called299-314
these
D. Atomic
Properties
& Atomic
Structure
substances electrolytes. Our definition today
an “Review
electrolyte
is much 1”
p. of
319
Question
the same. It is a substance that dissolves in water to form a solution that
#31,33,35,37,41,45,47,49,67,68,71,73,75,78,80,83,85,87,93,99,101,117,118,12
will conduct an electric current. The usual apparatus to test for this
2,123,135
conductivity is a light bulb placed in a series of twop.prongs
that are19, 20, 25
990 #13-15;
in the solution tested, as shown below. Solutions can be good,
III. immersed
Periodic Properties
moderate or poor electrolytes. Nonelectrolytes do not conduct at all.
A. Periodic Law
pages 299-309
B. Periodic Properties of Elements
314-318; chapters 19-21
2. Electrons: Thompson and Millikan – see above and below for more
Thomson