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Guided Notes
Chapter 4 (pgs. 100-127)
Section 4.1
Pages 102 - 105
Early Ideas about Matter
Democritus (460 – 370 BC)
• He thought matter was not _________ divisible, and
that matter was _______ up of tiny particles called ___________.
• He believed that atomos could not be _________,
destroyed, or divided.
• ____________________________________________
____________________________________________.
Aristotle (384 – 322 BC)
• Extremely well respected and influential philosopher.
• He did ________ believe that anything was empty, and that
atoms could not exist because they had ___________ space.
John Dalton (1766 – 1844)
• Revised _____________________________ ideas.
• Created Dalton’s Atomic Theory
• Matter is made up of ____________ (small particles)
that are ___________________ and
____________________.
• Atoms of the same _______________ are all the same
in regards to size, mass, and ____________________
properties
• Created _________________ Atomic Theory
• Different elements have different atoms.
• _______________________________________
• In a chemical reaction, atoms are ______________,
combined or ____________________.
Conservation of mass
• Mass is
____________________________________________________.
• The same number of atoms used as ______________, will be
present in the __________________________.
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•
General formula:
______________________________________
Comparison of Dalton and Democritus
Take some time to compare and contrast Dalton and Democritus using a
double bubble map.
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Section 4.2
Pages 106-114
Atoms
• Atoms are the ______________ particle of an element that retains
the __________________ of an element.
• Atoms are made up of three subatomic particles:
1. _______________
2. _______________
3. _______________
Label the atom:
•
We can view atoms using a scanning tunneling microscope
Discovery of the electron
Sir William Crookes
• Noticed a _____________ of light in the
__________________ ray.
• Lead to further research – determined that
________________ rays were a stream of
____________________ charged particles.
J.J. Thompson (1856-1940)
• Did a series of experiments to determine the ______________
of the cathode rays’ _________________________________.
• He compared the ________________ to mass ratio of
the ray to other known charge to _____________ ratios.
• Found that it was much ______________ than
hydrogen (H)
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•
Found the _______________
Robert Millikan (1868 – 1953)
• _________________________________________________
• Determined the _______________________ of an electron
• Used the _______________ to mass ratio to
_________________ the mass of an electron
Plum Pudding Model
• ________________ are negatively charged, but matter is neutral
overall
• J.J. Thompson proposed a model that had _________________
distributed ____________ matter with negative charges residing in
it.
Label the picture:
Discovery of the Nucleus
Rutherford’s Experiment
• Blasted a sheet of thin _____________ with __________
particles
• Expected: alpha _________________ to only move a little
• Actual: particles collided and went all over! _________ angles,
and some went ________________ back
• Concluded:
• There was a ________________.
• _____________________
• It contained the
_____________________________.
• The ______________________ (electrons) are
held in place by their ___________ to the positive
charges
Label the Picture:
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The Nucleus
• Contains:
• Proton: sub-atomic particle with a charge of ______________
• Neutron: sub-atomic particle with ____________________.
Mass is nearly equal to that of a proton
Summary of an Atom
• It is made up of _____________ sub-atomic particles with varying
properties
Proton
Electron
Neutron
Symbol
Charge
Location
Mass
Section 4.3
Pages 115 – 121
Atomic Number
• _________________: the number of protons in an atom.
• The # of _______________ are unique to each element.
Formula:
• Atomic mass = _________________
= ________________
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Practice: how many protons do the following elements have?
1. Carbon
2. Iron
3. Oxygen
4. Helium
5. Neon
6. Magnesium
Isotopes and Mass Number
• Isotopes: Have the same number of ________________, but have
different number of ____________________.
• ______________________________________________________
Natural Abundance
• In _____________ elements are found as a ___________ of
isotopes.
• This means not all _________ of elements have the _________
naturally.
• The atomic mass is simply a ___________ average of the
____________
Mass of Atoms
• Atomic mass unit (amu):
• Standard unit of _______________
• Is _____________ the mass of a carbon atom.
• 1 amu = 1 _________________________________
• Isotope Abundance:
• The atomic __________ is a weighted average. Most of the
time it can also tells you which _____________ is most
______________.
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Example Problem: Atomic Mass
• Question: Rubidium is a soft, silvery-white metal that has two
common isotopes, 85Rb and 87Rb. If the abundance of 85Rb is
72.2% and the abundance of 87Rb is 27.8%, what is the average
atomic mass of rubidium?
Step one: Write the given
Step 2: make the percentages into decimals
Step 3: Find the average
Practice Question
•
Question: Uranium is used in nuclear reactors and is a rare element
on earth. Uranium has three common isotopes. If the abundance of
234
U is 0.01%, the abundance of 235U is 0.71%, and the abundance
of 238U is 99.28%, what is the average atomic mass of uranium?
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Section 4.4
Pages 122 – 125
Radioactivity
• Nuclear reaction
• Changes an ____________ into a new
___________________.
• Involves a change in the _____________ of an atom
• Radiation:
• Rays and particles ____________ from radioactive
____________
• Radioactivity
• When a substance __________________ emits radiation
Practice Question:
• Create a Double Bubble map about the similarities and differences
between a chemical reaction, and a radioactive reaction.
Radioactive Decay
• It occurs when _________________ nuclei spontaneously lose
energy by emitting _____________________
• ______________________________________________________
• Often becomes a different element
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Radiation Experiments
• Occurs by _________________ a radiation from a radioactive
source between 2 electrically __________________ plates.
• Scientists discovered 3 types of radiation:
• ________________________________________
• ________________________________________
• ________________________________________
Alpha Radiation
• Deflected towards the ________________ charged plate.
• Made up of alpha _________________
• Symbol is α
• ___________ particles
• have __________ protons, and_____________ neutrons.
• A _______________ overall charge
• Reaction___________________________________________
Beta Radiation
• Deflected towards the ______________ plate
• Made up by ___________ moving _________________
particles
• Symbol is______________ or β
• Beta particles
• Made up of _____________________
• Has an overall _______________ charge
• Reaction___________________________________________
Gamma Radiation
• Also known as __________________ rays
• High energy radiation that has
____________________________.
• Did not _______________ towards any electrical
_______________
• Can _________ be deflected by electric or ______________
fields
• Cannot result in the
_____________________________________.
• ________________ is y
• Reacttion___________________________________________
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