Transcript Chapter 4 Notes - Buckeye Valley

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Bellringers
Chapter Presentation
Transparencies
Standardized Test Prep
Visual Concepts
Math Skills
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Chapter 4
Atoms and the Periodic Table
Table of Contents
Section 1 Atomic Structure
Section 2 A Guided Tour of the Periodic Table
Section 3 Families of Elements
Section 4 Using Moles to Count Atoms
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Chapter 4
Section 1 Atomic Structure
Objectives
• Explain Dalton’s atomic theory, and describe why it
was more successful than Democritus’s theory.
• State the charge, mass, and location, of each part of
an atom according to the modern model of the atom.
• Compare and contrast Bohr’s model with the modern
model of the atom.
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Chapter 4
Section 1 Atomic Structure
Bellringer
When scientists wanted to find out what an atom was,
they were not able to look directly at what the atom was
made of. They had to make inferences from the results
of many different experiments. It was like trying to
describe a picture, such as the one on the next slide,
with only small portions visible.
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Chapter 4
Section 1 Atomic Structure
Bellringer
1. Write four sentences describing what you can see of
the above picture.
2. What information or parts of the picture would make
your descriptions more accurate without revealing
the entire picture?
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Chapter 4
Section 1 Atomic Structure
What Are Atoms?
• Our understanding of atoms required many centuries.
• The idea of an atom—which means “unable to be
divided”—dates back to the Greek philosopher
Democritus, who lived in the fourth century BCE.
• John Dalton developed an atomic theory in 1808.
• Like Democritus, Dalton proposed that atoms
could not be divided. Dalton’s was the first
atomic theory with a scientific basis.
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Chapter 4
Section 1 Atomic Structure
What Are Atoms? continued
• An atom is the smallest part of an element that still
has the element’s properties.
• Atoms are the building blocks of molecules.
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Chapter 4
Section 1 Atomic Structure
Atom
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Chapter 4
Section 1 Atomic Structure
What’s in an Atom?
• Atoms are made of protons, neutrons, and electrons.
• At the center of each atom is a small, dense
nucleus with a positive electric charge.
• The nucleus is made of protons (a subatomic
particle that has a positive charge) and neutrons
(a subatomic particle that has no charge).
• Moving around outside the nucleus is a cloud
of electrons: subatomic particles with
negative charges.
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Chapter 4
Section 1 Atomic Structure
Parts of the Atom
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Chapter 4
Section 1 Atomic Structure
What’s in an Atom? continued
• Unreacted atoms have no overall charge.
• Although atoms are made of charged particles,
they do not have an overall charge because they
have an equal number of protons and electrons
whose charges exactly cancel.
• To the right is shown a helium
atom, which is made of two
protons, two neutrons, and
two electrons.
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Chapter 4
Section 1 Atomic Structure
Models of the Atom
• Bohr’s model compares electrons to planets.
• In 1913, the Danish scientist Niels Bohr suggested
that electrons in an atom move in set paths
around the nucleus much like the planets orbit the
sun in our solar system.
• In Bohr’s model, electrons can only be in certain
energy levels. Bohr’s model of electrons is
illustrated on the following slide.
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Chapter 4
Section 1 Atomic Structure
Building Model
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Chapter 4
Section 1 Atomic Structure
Bohr Model of the Atom
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Chapter 4
Section 1 Atomic Structure
Models of the Atom, continued
• Electrons act more like waves.
• By 1925, Bohr’s model of the atom no longer
explained electron behavior.
• A new model was proposed, in which electrons
behave more like waves on a vibrating string than
like particles.
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Chapter 4
Section 1 Atomic Structure
Models of the Atom, continued
• An electron’s exact location cannot be determined.
• It is impossible to determine both the exact
location of an electron in an atom and the
electron’s speed and direction.
• The best scientists can do is calculate the chance
of finding an electron in a certain place within
an atom.
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Chapter 4
Section 1 Atomic Structure
Models of the Atom, continued
• Electrons exist in energy levels.
• The number of filled energy levels an atom
has depends on the number of electrons.
• The figure to the right
shows how the first four
energy levels are filled.
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Chapter 4
Section 1 Atomic Structure
Electron Energy Levels
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Chapter 4
Section 1 Atomic Structure
Models of the Atom, continued
• Electrons are found in orbitals within energy levels.
• An orbital is a region in an atom where there is a high
probability of finding electrons.
• An s orbital is shaped like a sphere:
• A p orbital is dumbbell shaped and
can be oriented three different ways in space:
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Chapter 4
Section 1 Atomic Structure
Models of the Atom, continued
• Every atom has between one and eight
valence electrons.
• Valence electrons are found in the outermost
shell of an atom and determine the atom’s
chemical properties.
• Valence electrons are the electrons in an atom
that participate in chemical bonding.
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Chapter 4
Section 1 Atomic Structure
Valence Electrons
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Chapter 4
Section 2 A Guided Tour of the
Periodic Table
Objectives
• Relate the organization of the periodic table to the
arrangement of electrons within an atom.
• Explain why some atoms gain or lose electrons to
form ions.
• Determine how many protons, neutrons, and
electrons an atom has, given its symbol, atomic
number, and mass number.
• Describe how the abundance of isotopes affects an
element’s average atomic mass.
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Chapter 4
Section 2 A Guided Tour of the
Periodic Table
Bellringer
One way to organize a large group of objects is to arrange them
into groups of similar objects. This is how scientists organize all of
the many elements. Practice the skill of categorizing by arranging
the magazines listed below into similar groups.
Calling All Girls
Computer World
Beautiful Homes
Auto Racing
The Healthy Man
Sporting Times
Child’s Play
Family Computing
Beautiful Homes
Car Trends
Homeopathic Medicine
Sports and Scores
Calling All Boys
All About Computing
Home Decorating
Classic Cars
The Healthy Woman
Golf for Everyone
Nursery Rhymes
How to Use the Internet
Modern Housekeeping
Easy Car Repairs
The Health Newsletter
Football Stories
Read Aloud Stories
Building a Web Site
Home Makers Magazine
The Sports Car Story
Good Nutrition
Tennis Tips
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Chapter 4
Section 2 A Guided Tour of the
Periodic Table
Bellringer
1. What criteria did you use for grouping the
magazines?
2. Once you arrange the magazines into groups, could
you sort the material further to make it even more
organized?
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Chapter 4
Section 2 A Guided Tour of the
Periodic Table
Organization of the Periodic Table
• The periodic table groups similar elements together.
• This organization makes it easier to predict the
properties of an element based on where it is in
the periodic table.
• Elements are listed in order of number of protons,
because the periodic law states that when
elements are arranged this way, similarities in
their properties will occur in a regular pattern.
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Chapter 4
Section 2 A Guided Tour of the
Periodic Table
Organization of the Periodic Table, continued
• The periodic table helps determine electron
arrangement.
• Horizontal rows in the periodic table are
called periods.
• Just as the number of protons an atom has
increases as you move from left to right across a
period, so does its number of electrons.
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Chapter 4
Section 2 A Guided Tour of the
Periodic Table
Organization of the Periodic Table, continued
• Elements in the same group have similar properties.
• A group is a vertical column of elements in the
periodic table.
• Atoms of elements in the same group have the
same number of valence electrons, so these
elements have similar properties.
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Chapter 4
Section 2 A Guided Tour of the
Periodic Table
How Do the Structures of Atoms Differ?
• The atomic number, Z, of an atom equals the
number of protons in the nucleus.
• The mass number, A, of an atom equals the
number of protons plus the number of neutrons in
the nucleus.
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Chapter 4
Section 2 A Guided Tour of the
Periodic Table
Nucleus
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Chapter 4
Section 2 A Guided Tour of the
Periodic Table
Atomic Number
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Chapter 4
Section 2 A Guided Tour of the
Periodic Table
Mass Number
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Chapter 4
Section 2 A Guided Tour of the
Periodic Table
Some Atoms Form Ions
• An ion is an atom or group of atoms that has lost
or gained one electrons and has a negative or
positive charge.
• A lithium atom loses one electron to form a 1+ charged ion:
• A fluorine atom gains one electron to form a 1 charged ion:
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Chapter 4
Section 2 A Guided Tour of the
Periodic Table
Ion
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Chapter 4
Section 2 A Guided Tour of the
Periodic Table
How Do the Structures of Atoms Differ?
continued
• An isotope is an atom that has the same number of
protons as other atoms of the same element do but
that has a different number of neutrons.
• Example: Hydrogen has three isotopes, shown
below.
• Some isotopes are more common than others.
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Chapter 4
Section 2 A Guided Tour of the
Periodic Table
How Do the Structures of Atoms Differ?
continued
• If you know the atomic number and mass number
of an atom, you can calculate the number of
neutrons it has.
• Example: uranium-235 has a mass number of
235. Like all uranium atoms, it has an atomic
number of 92. The number of neutrons it has is
therefore:
Mass number (A):
Atomic number (Z):
Number of neutrons:
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235
–92
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Chapter 4
Section 2 A Guided Tour of the
Periodic Table
Isotopes
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Chapter 4
Section 2 A Guided Tour of the
Periodic Table
How Do the Structures of Atoms Differ? continued
• Because the mass of a single atom is so tiny, atomic
masses are usually expressed in atomic mass units.
• An atomic mass unit (amu) is equal to one twelfth of
the mass of a carbon-12 atom.
• The average atomic mass for an element is a
weighted average of the masses of all naturallyoccurring isotopes of an element.
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Chapter 4
Section 2 A Guided Tour of the
Periodic Table
Average Atomic Mass
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Chapter 4
Section 3 Families of Elements
Objectives
• Locate alkali metals, alkaline-earth metals, and
transition metals in the periodic table.
• Locate semiconductors, halogens, and noble gases
in the periodic table.
• Relate an element’s chemical properties to the
electron arrangement of its atoms.
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Chapter 4
Section 3 Families of Elements
Bellringer
Are you familiar with some of the elements on the periodic table? There
are probably many more elements that you have never heard of before.
You may be surprised to learn that even though you have never heard of a
certain element before, by looking at the periodic table, you can guess
some of the characteristics of that element. The periodic table organizes
elements into groups that have similar characteristics.
1. The elements below are classified as metals. You may be familiar
with some of these elements. If you know of a specific use for an element
listed below, write it down.
Silver, Ag
Gold, Au
Tin, Sn
Copper, Cu
Lead, Pb
Mercury, Hg
Aluminum, Al
Platinum, Pt
2. Can you think of any characteristics that the metals have in common?
Do any of the metals have similar uses?
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Chapter 4
Section 3 Families of Elements
Bellringer
3. The elements below are classified as nonmetals. You
may be familiar with some of these elements. If you
know of a specific use for an element listed below, write
it down.
Helium, He Chlorine, Cl Oxygen, O
Iodine, I
Neon, Ne
Carbon, C
4. Look at the periodic table and notice where each of
the elements listed in questions 1 and 3 is located.
Where are the metals located? Where are the
nonmetals located?
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Chapter 4
Section 3 Families of Elements
How Are Elements Classified?
• The elements are classified into three groups.
• Most elements are metals, elements that are
shiny and conduct heat and electricity well.
• Nonmetals, all except hydrogen of which are
found on the right side of the periodic table, may
be solids, liquids, or gases at room temperature.
• Between these groupings are semiconductors,
elements that can conduct electricity under
certain conditions.
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Chapter 4
Section 3 Families of Elements
How Are Elements Classified? continued
• The periodic table below shows the distribution of
metal, nonmetals, and semiconductors in the
periodic table.
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Chapter 4
Section 3 Families of Elements
Metals
• The alkali metals, found in Group 1
of the periodic table, are very reactive.
• The alkaline-earth metals, which
include calcium, are found in
Group 2 of the periodic table, and
are somewhat less reactive than the
alkali metals.
• The transition metals, such as gold,
iron, and mercury, occupy Groups
3–12 of the periodic table.
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Chapter 4
Section 3 Families of Elements
Nonmetals
• Carbon is found in three different forms and can form many
compounds.
• Nonmetals and their compounds
are plentiful on Earth.
• Halogens, such as chlorine, are
located in Group 17 of the
periodic table.
• Noble gases, such as neon, make
up Group 18 of the periodic table.
They are unreactive.
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Chapter 4
Section 3 Families of Elements
Nonmetals, continued
• Semiconductors are intermediate
conductors of heat and electricity.
• Silicon is the most familiar semiconductor.
• Silicon is an important part of computer chips, as
well as other semiconductor devices such as
transistors, LED display screens, and solar cells.
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Chapter 4
Section 3 Families of Elements
Comparing Metals, Nonmetals, and Metalloids
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Chapter 4
Section 4 Using Moles to
Count Atoms
Objectives
• Explain the relationship between a mole of a
substance and Avogadro’s constant.
• Find the molar mass of an element by using the
periodic table.
• Solve problems converting the amount of an element
in moles to its mass in grams, and vice versa.
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Chapter 4
Section 4 Using Moles to
Count Atoms
Bellringer
Sometimes when you are dealing with numbers of things, it is
convenient to have a special unit that designates a specific number
of the objects. Below are examples of special units that are used to
count objects.
1. How many objects are in each sample?
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Chapter 4
Section 4 Using Moles to
Count Atoms
Bellringer, continued
2. What if you want to use six sticks of butter, but you
only have a large block of butter and a scale? How
could you get the equivalent of six sticks of butter
without the mess of dividing the large block into sticks?
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Chapter 4
Section 4 Using Moles to
Count Atoms
Counting Things
• There are many different counting units: for example,
eggs are packaged by the dozen.
• The mole is useful for counting small particles.
• A mole (abbreviation: mol) is the number of
particles that is the same as the number of atoms
of carbon in 12 g of carbon-12.
• Avogadro’s constant is the number of particles
per mole of a substance: 6.022 × 1023
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Chapter 4
Section 4 Using Moles to
Count Atoms
The Mole
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Chapter 4
Section 4 Using Moles to
Count Atoms
Avogadro’s Number
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Chapter 4
Section 4 Using Moles to
Count Atoms
Counting Things, continued
• Moles and grams are related.
• The mass in grams of 1 mol of a substance is called
its molar mass.
• For example, 1 mol of carbon-12 atoms has a
molar mass of 12.00 g.
• The molar mass of an element
is its average atomic mass, which
is listed in the periodic table.
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Chapter 4
Section 4 Using Moles to
Count Atoms
Molar Mass
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Chapter 4
Section 4 Using Moles to
Count Atoms
Calculating with Moles
• To convert between moles and grams and vice versa,
you can use a conversion factor: a ratio that is
derived from the equality of two different units.
• Let’s say that a shopkeeper knows that exactly
10 gumballs have a total mass of 21.4 g. This
relationship can be written as either one of two
equivalent conversion factors:
10 gumballs
21.4 g
21.4 g
10 gumballs
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Chapter 4
Section 4 Using Moles to
Count Atoms
Conversion Factor
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Chapter 4
Section 4 Using Moles to
Count Atoms
Math Skills
Conversion Factors What is the mass of exactly
50 gumballs?
1. List the given and unknown values.
Given:
mass of 10 gumballs = 21.4 g
Unknown: mass of 50 gumballs = ? g
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Chapter 4
Section 4 Using Moles to
Count Atoms
Math Skills, continued
2. Write down the conversion factor that converts
number of gumballs to mass.
The conversion factor you choose should have the
unit you are solving for (g) in the numerator and the
unit you want to cancel (number of gumballs) in the
denominator.
21.4 g
10 gumballs
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Chapter 4
Section 4 Using Moles to
Count Atoms
Math Skills, continued
3. Multiply the number of gumballs by this
conversion factor, and solve.
21.4 g
50 gumballs 
 107 g
10 gumballs
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Chapter 4
Section 4 Using Moles to
Count Atoms
Calculating with Moles, continued
• An element’s molar mass can be used as a
conversion factor.
• The diagram below shows how to set up the
conversion factor, depending on whether you
want to convert from amount to mass or the other
way around.
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Chapter 4
Section 4 Using Moles to
Count Atoms
Math Skills
Converting Amount to Mass Determine the mass in
grams of 5.50 mol of iron.
1. List the given and unknown values.
Given:
amount of iron = 5.50 mol Fe
molar mass of iron = 55.85 g/mol Fe
Unknown:
mass of iron = ? g Fe
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Chapter 4
Section 4 Using Moles to
Count Atoms
Math Skills, continued
2. Write down the conversion factor that converts
moles to grams.
The conversion factor you choose should have what
you are trying to find (grams of Fe) in the numerator
and what you want to cancel (moles of Fe) in the
denominator.
55.85 g Fe
1 mol Fe
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Chapter 4
Section 4 Using Moles to
Count Atoms
Math Skills, continued
3. Multiply the amount of iron by this conversion
factor, and solve.
55.85 g Fe
5.50 mol Fe 
 307 g Fe
1 mol Fe
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Chapter 4
Section 4 Using Moles to
Count Atoms
Math Skills
Converting Mass to Amount Determine the amount of
iron present in 352 g of iron.
1. List the given and unknown values.
Given:
mass of iron = 352 g Fe
molar mass of iron = 55.85 g/mol Fe
Unknown: amount of iron = ? mol Fe
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Chapter 4
Section 4 Using Moles to
Count Atoms
Math Skills, continued
2. Write down the conversion factor that converts
grams to moles.
The conversion factor you choose should have what
you are trying to find (moles of Fe) in the numerator
and what you want to cancel (grams of Fe) in the
denominator.
1 mol Fe
55.85 g Fe
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Chapter 4
Section 4 Using Moles to
Count Atoms
Math Skills, continued
3. Multiply the mass of iron by this conversion
factor, and solve.
1 mol Fe
352 g Fe 
 6.30 mol Fe
55.85 g Fe
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Chapter 4
Section 4 Using Moles to
Count Atoms
Concept Mapping
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Chapter 4
Standardized Test Prep
Understanding Concepts
1. Why do atoms gain or lose electrons?
A. to balance the charges between the nucleus and
the electron cloud
B. to obtain a more stable electron configuration
through a full outermost orbital
C. to place electrons in higher energy levels than
are occupied in the atom
D. to reduce the amount of energy required to bring
atoms closer together
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Chapter 4
Standardized Test Prep
Understanding Concepts
1. Why do atoms gain or lose electrons?
A. to balance the charges between the nucleus and
the electron cloud
B. to obtain a more stable electron configuration
through a full outermost orbital
C. to place electrons in higher energy levels than
are occupied in the atom
D. to reduce the amount of energy required to bring
atoms closer together
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Chapter 4
Standardized Test Prep
Understanding Concepts
2. Why are the Group 18 elements nonreactive?
F. They have no valence electrons.
G. They combine to form stable molecules.
H. Their outermost energy levels are completely
filled.
I. They are too rare to react with significant
amounts of other elements.
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Chapter 4
Standardized Test Prep
Understanding Concepts
2. Why are the Group 18 elements nonreactive?
F. They have no valence electrons.
G. They combine to form stable molecules.
H. Their outermost energy levels are completely
filled.
I. They are too rare to react with significant
amounts of other elements.
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Chapter 4
Standardized Test Prep
Understanding Concepts
3. Antimony is a shiny, brittle solid that conducts
electricity under some conditions but does not
conduct in other conditions. How is antimony
classified on the modern periodic table?
A.
B.
C.
D.
metals
nonmetal
semiconductor
transition element
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Chapter 4
Standardized Test Prep
Understanding Concepts
3. Antimony is a shiny, brittle solid that conducts
electricity under some conditions but does not
conduct in other conditions. How is antimony
classified on the modern periodic table?
A.
B.
C.
D.
metals
nonmetal
semiconductor
transition element
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Chapter 4
Standardized Test Prep
Understanding Concepts
4. Beryllium is located on the same row of the periodic
table as fluorine, while iodine is located in the same
column. Identify which element, beryllium or iodine,
will form an ion by gaining one electron, as fluorine
does, and explain your answer.
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Chapter 4
Standardized Test Prep
Understanding Concepts
4. Beryllium is located on the same row of the periodic
table as fluorine, while iodine is located in the same
column. Identify which element, beryllium or iodine,
will form an ion by gaining one electron, as fluorine
does, and explain your answer.
Answer: Iodine will form an ion by gaining one electron,
because all of the elements within a column have
the same valence electron structure.
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Chapter 4
Standardized Test Prep
Reading Skills
Read the passage below. Then answer the question.
Particle accelerators are devices that speed up
charged particles to speeds close to the speed of
light in order to smash them together and observe
the results. In many cases, these collisions form a
new atomic nucleus. This nucleus attracts electrons
and becomes a neutral atom. Atoms formed this way
can either be an isotope of a known element or a
previously unknown element.
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Chapter 4
Standardized Test Prep
Reading Skills
5. Determine how scientists can judge whether the
newly formed material is a new element or a new
isotope of an existing element.
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Chapter 4
Standardized Test Prep
Reading Skills
5. Determine how scientists can judge whether the
newly formed material is a new element or a new
isotope of an existing element.
Answer: They can investigate its chemical and physical
properties and compare them to known elements.
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Chapter 4
Standardized Test Prep
Interpreting Graphics
Base your answer to question 6 on the illustration
below, which shows the ionization of a fluorine atom.
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Chapter 4
Standardized Test Prep
Interpreting Graphics
6. Why is the fluoride ion larger than the fluorine atom?
F. The electrons experience a greater electrical
repulsion.
G. The interaction between the electrons and the
protons is stronger.
H. The ion has more protons than electrons so it is
not as stable as the atom.
I. The addition of another electron makes the ion
substantially more massive than the atom.
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Chapter 4
Standardized Test Prep
Interpreting Graphics
6. Why is the fluoride ion larger than the fluorine atom?
F. The electrons experience a greater electrical
repulsion.
G. The interaction between the electrons and the
protons is stronger.
H. The ion has more protons than electrons so it is
not as stable as the atom.
I. The addition of another electron makes the ion
substantially more massive than the atom.
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Copyright © by Holt, Rinehart and Winston. All rights reserved.