Download Chapter 4 Review Packet Section 4.1

Name: ________________
Date: 10/15/14
Period: ____
Chapter 4 Review Packet
Section 4.1
TERMS
•
Atom: the smallest particle of an element that retains its identity in a chemical reaction
•
Dalton’s atomic theory: the first theory to relate chemical changes to events at the atomic level
KEY CONCEPTS:
•
Democritus reasoned that atoms were indivisible and indestructible. By using experimental
methods, Dalton transformed Democritus’s ideas on atoms into a scientific theory.
•
Scientists can observe individual atoms by using instruments such as scanning electron
microscopes.
HISTORY OF THE ATOM- Philosophers and Scientists (Sections 4.1 & 4.2)







Democritus
John Dalton
J.J Thomson
Robert Millikan
Eugen Goldstein
James Chadwick
Ernest Rutherford
MODELS (Section 4.1 & 4.2)




Cathode Ray Tube
Plum Pudding Model
Rutherford’s Gold Foil Experiment
Nuclear Atomic Model
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Name: ________________
Date: 10/15/14
Period: ____
HISTORY OF THE ATOM (Section 4.1 & 4.2)
Democritus
•Among the first to suggest the exists of atoms
•Reasoned that the atom was indivisible and indestructable
•Democritus ideas agreed with scientific theory, but did not include chemical behavior and had a lack
of experimental support.
John Dalton
•By using experimental methods, Dalton transformed Democritus's ideas on atoms into scientific
theory
•He studied the ratios in which elements combine in chemical reactions.
•Dalton's Atomic Theory
•All elements are composed of tiny indivisible particles called atoms.
•Atoms of the same element are identical. The atoms of any one element are different from those
of any other element.
•Atoms of different elements can physically mix together or can chemically combine in simple
whole-number ratios to form compounds.
•Chemical reactions occur when atoms are separated from each other, joined, or rearranged in
different combinations. Atoms of one element are never changed into atoms of another element
as a result of a chemical reaction.
J.J Thomson
•Found the electron
•Made the "Plum Pudding Model"
Robert Milllikan
•Found the charge of the electron using the Oil Drop Experiment
•Determined the mass of the electron
Eugen Goldstein
•Found the proton
James Chadwick
•Found the neutron
Ernest Rutheford
•Gold Foil Experiment
•Shot alpha particles at a piece of gold foil and expected them all to just pass through; however he
found that some of the aplha particles bounced back or in different directions.
•Found that atoms have a small dense mass in the center called the nucleus
•Found that the atoms was made up fo mostly empty space
•Nuclear Atom: Rutherford determine that the nuclear atom had protons and neutrons in a
positively charged nucleus. The electrons are distributeda round the nucleus and occupy almost all
the volume of the atoms.
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Name: ________________
Date: 10/15/14
Period: ____
Section 4.2
TERMS
•
electron: a negatively charged subatomic particle
•
cathode ray: a stream of electrons produced at the negative electrode (cathode) of a tube
containing a gas at low pressure
•
proton: a positively charged subatomic particle found in the nucleus of an atom
•
neutron: a subatomic particle with no charge and a mass of 1 amu; found in the nucleus of an
atom
•
nucleus: the tiny, dense central portion of an atom, composed of protons and neutrons
KEY CONCEPTS
•
Three kinds of subatomic particles are electrons, protons, and neutrons.
•
In the nuclear atom, the protons and neutrons are located in the nucleus. The electrons are
distributed around the nucleus and occupy almost all the volume of the atom.
PARTS OF THE ATOM



Protons
Neutrons
Electrons
J.J THOMSON EXPERIMENT

Cathode Ray Tube
o Electrons (See table on previous page)
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Name: ________________
Date: 10/15/14
Period: ____

Plum Pudding Model
o Positively charged sphere with spots of electrons throughout.
RUTHERFORD’ S GOLD FOIL EXPERIMENT

Gold Foil Experiment:
o
o
o
In the experiment, a narrow beam of alpha particles was directed at a very thin sheet of
gold.
According to the prevailing theory, the alpha particles should have passed easily through
the gold, with only a slight deflection due to the positive charge thought to be spread
out in the gold atoms.
Rutherford’s results were that most alpha particles went straight through, or were
slightly deflected.
 What was surprising is that a small fraction of the alpha particles bounced off
the gold foil at very large angles.
 Some even bounced straight back toward the source.
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Name: ________________
Date: 10/15/14
Period: ____
RUTHERFORD’ S NUCLEAR ATOM

Nuclear Atomic Model
o In the nuclear atom, the protons and neutrons are located in the positively charged
nucleus. The electrons are distributed around the nucleus and occupy almost all the
volume of the atom.
Section 4.3
TERMS
•
atomic number: the number of protons in the nucleus of an atom of an element
•
mass number: the total number of protons and neutrons in the nucleus of an atom
•
isotopes: atoms of the same element that have the same atomic number but different atomic
masses due to a different number of neutrons
•
atomic mass unit (amu): a unit of mass equal to one-twelfth the mass of a carbon-12 atom
•
atomic mass: the weighted average of the masses of the isotopes of an element
KEY CONCEPTS
•
Elements are different because they contain different numbers of protons.
•
Because isotopes of an element have different numbers of neutrons, they also have different
mass numbers.
•
To calculate the atomic mass of an element, multiply the mass of each isotope by its natural
abundance, expressed as a decimal, and then add the products.
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Name: ________________
Date: 10/15/14
Period: ____
KEY EQUATION:
DISTINGUISHING AMONG ATOMS
Protons, Neutrons, Electrons, & Mass Number
ATOMIC NUMBER


Elements are different because they contain different numbers of protons.
Remember that atoms are electrically neutral.
o Thus, the number of electrons (negatively charged particles) must equal the number of
protons (positively charged particles).
MASS NUMBER

The total number of protons and neutrons in an atom is called the mass number.
Example:
Helium has an atomic number of 2 and 2 neutrons, therefore helium’s mass number is 4.
4
2+2=4
2𝐻𝑒
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Name: ________________
Date: 10/15/14
Period: ____
SHORT H AND NOTATION

The composition of any atom can be represented in shorthand notation using atomic number
and mass number.
Mass Number 
o The atomic number is the subscript.
Chemical Symbol
Atomic
Number

o The mass number is the superscript.
14
7𝑁

You can also refer to atoms by using the mass number and the name of the element.
197
79
Au
may be written as gold-197
ISOTOPES
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All have the same number of protons (10).
All have the same number of electrons (10).
But they each have different numbers of neutrons.
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Name: ________________
Date: 10/15/14
Period: ____
ATOMIC MASS
•
The atomic mass of an element is a weighted average mass of the atoms in a naturally occurring
sample of the element.
•
An atomic mass unit (amu) is defined as one-twelfth of the mass of a carbon-12 atom.
Determining the atomic mass:
•
To calculate the atomic mass of an element, multiply the mass of each isotope by its natural
abundance, expressed as a decimal, and then add the products.

You can determine atomic mass based on relative abundance.
o To do this, you must know three things:
1. number of stable isotopes of the element,
2. mass of each isotope,
3. natural percent abundance of each isotope.
4.3 Distinguishing Among Atoms > Atomic Mass
Carbon has two stable isotopes: carbon-12,
which has a natural abundance of 98.89 percent,
and carbon-13, which has a natural abundance of
1.11 percent.
• The mass of carbon-12 is 12.000 amu; the mass
of carbon-13 is 13.003 amu.
• The atomic mass of carbon is calculated as
follows:
Atomic mass of carbon = (12.000 amu x 0.9889) + 13.003 amu x 0.0111)
= (11.867 amu) + (0.144 amu)
= 12.011 amu
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Name: ________________
Date: 10/15/14
Period: ____
Chapter 4 Review Questions
Responses:
1. How did Democritus describe atoms?
2. How did John Dalton advance the atomic philosophy proposed by Democritus?
3. What instrument is used to observe individual atoms?
4. What are the three types of subatomic particle? Define each.
5. How does the Rutherford model describe the structure of the atom (discuss nucleus and empty
space-electrons)?
6. What are the charges and actual masses of the three main subatomic particles?
7. Describe Thomson and Millikan’s contributions to the atom.
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Name: ________________
Date: 10/15/14
Period: ____
8. What distinguishes one atom from another atom?
9. What does the atomic number of each atom represent?
10. How do isotopes of given elements differ from each other?
11. What equation tells you how to calculate the number of neutrons in an atom?
12. How is atomic number different from mass number?
Completion:
13. Name each picture and Label each picture with the appropriate scientist: J.J Thomson, Ernest
Rutherford, or Niels Bohr
a.
______________________________________
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Name: ________________
Date: 10/15/14
Period: ____
b.
____________________________________
c.
________________________________
14. How many protons are in each of the following elements (atoms). Use a periodic table of
needed.
a. Phosphorus (P)
________
b. Molybdenum (Mo)
________
c. Aluminum (Al)
________
d. Cadmium (Cd)
________
e. Chromium (Cr)
________
f. Lead (Pb)
________
15. Determine the protons, electrons, and neutron fro elements from their chemical symbols.
Protons
Electrons
Neutrons
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g. 26𝐹𝑒
_____
______
_____
35
h. 17𝐶𝑙
_____
______
_____
39
i. 19𝐾
_____
______
_____
201
j.
_____
______
_____
80𝐻𝑔
64
k. 29𝐶𝑢
_____
______
_____
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Name: ________________
Date: 10/15/14
Period: ____
16. Complete the following table.
Atomic Number
9
c. _______
e. _______
g. _______
o
o
o
Mass Number
a. ______
d. ______
47
55
Number of Protons
b. ______
14
f. _______
25
Number of Neutrons
10
15
25
h. _____
Mass Number = Number of Protons (atomic number) + Number of Neutrons
Number of Neutrons = Mass Number – Number of Protons (atomic number)
Atomic Number (Number of Protons) = Mass Number – Number of Neutrons
17. Lithium has two isotopes: Lithium-6 (atomic mass= 6.015, relative abundance = 7.5 %) and
Lithium-7 (atomic mass = 7.016, relative abundance = 92.6 %).
Calculate the atomic mass of lithium.
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