Chapter 8
“Introduction to the
PERIODIC TABLE”
8.1 The Modern Periodic Table
Objectives
• Describe the kinds of information
provided by the periodic table.
• Explain the structure of the periodic
table in terms of the periods and groups
• Generalize about the properties of
metals, nonmetals, and metalloids on the
periodic table.
• Organize data to develop a table of
atomic masses.
The Modern Periodic Table
• Imagine looking for the answer to a
homework question in a book with no
table of contents! You would have to
thumb through the book-page by page.
• Why is it easier to find information
in a book with a table of con tents?
• Data that have been organized are
easier to find, compare, and interpret.
The Modern Periodic Table
• One kind of table you use often is a calendar.
• Think of the calendar as a grid made up of
horizontal rows and vertical columns. Each
column represents a different day of the week.
Each day is repeated in every row through the
whole month.
• This arrangement of the days in the month is
periodic. Things that are periodic have a
regular, repeating pattern.
The Modern Periodic Table
• Like the days of the month, the
chemical elements can be arranged in a
way that shows a repeating, or periodic,
pattern.
• The chemical properties of the
elements repeat as the elements
increase in atomic number.
• A table that shows these patterns in
the elements' properties is called a
periodic table.
The Modern Periodic Table
The Modern Periodic Table
• At that time, chemists had
identified about 70 elements.
• Mendeleev wrote each
element's name, atomic mass,
and properties on a card. He
ordered the cards from
lowest to highest atomic mass
and pinned them to his
laboratory wall.
In 1869, a Russian chemist • He grouped elements that
named Dmitri Mendeleev had similar properties and put
created the first periodic these cards in rows along the
wall.
table of the elements.
The Modern Periodic Table
The Modern Periodic Table
• Arranging the elements in this way,
Mendeleev ran into several problems.
• So, he left spaces where no element
seemed to fit and put question marks in
these spaces.
• Mendeleev predicted the properties of
elements that would be discovered to fill
in the blank spaces.
• One element he left space for, gallium,
was discovered in 1875.
The Modern Periodic Table
•
After Mendeleev's death, a British
physicist named Henry Moseley carried
on Mendeleev's work.
• Moseley arranged the elements in order of
increasing atomic number instead of atomic
mass. He discovered that the pattern had no
irregularities.
• The position of an element in the modern
periodic table is related to its atomic number
and the arrangement of electrons in its energy
levels.
The Modern Periodic Table
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The Modern Periodic Table
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The Modern Periodic Table
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The Modern Periodic Table
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The Modern Periodic Table
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The Modern Periodic Table
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The Modern Periodic Table
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The Modern Periodic Table
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Science & Technology
8.2 Metals
Objectives
• Describe common properties
of metals.
• Generalize about the trend in
Groups 13 through 16.
• Classify metals using the
periodic table.
Properties of Metals
• Metals share many of the same
properties.
• Most metals are silvery or gray in color.
When polished, they usually have a
surface that reflects light, a quality
called luster.
• Luster is one of the properties
of metals.
• Metals also conduct heat
and electricity.
Properties of Metals
• Most metals are hard and have high melting
points, but there are many exceptions.
• For example, pure gold and pure silver are
relatively soft, so they are not often used
alone in jewelry and coins.
• A few metals, such as gallium, have melting
points that aren't much higher than room
temperature.
• One metal, mercury, is actually a liquid at
room temperature.
Properties of Metals
• One of the most useful properties of
metals is malleability.
• Materials that are malleable can be
flattened, bent, and shaped without
breaking. Aluminum, for example, can be
flattened into foil.
• Most metals are also ductile.
• They can be pulled into wire.
Properties of Metals
• Why do metals share all these properties?
• Atoms have their electrons arranged in
different energy levels. The electrons in the
highest energy level are most important,
because they determine an element's
properties.
• Although metals have very different total
numbers of electrons, most have from one to
three electrons in the highest energy level.
Properties of Metals
• This low number of outer electrons is
what gives metals their properties.
• A metal atom gives up its outer
electrons very easily.
• When many metal atoms are combined,
they all share their outer electrons.
• These electrons move in a "cloud"
around the metal atoms. As a result, a
metal can change shape without breaking.
Properties of Metals
• The metal atoms slide past each other..
• This behavior makes metals ductile and
malleable.
• And they conduct electricity because
the electrons are free to move.
Life Science Link
Alkali Metals
• Group 1 in the periodic table contains six
elements known as the alkali metals.
• The alkali metals are very reactive.
• They all have just one electron in the
highest energy level of their atoms.
• Because this electron is so easily lost,
alkali metals are found in nature only as
positively-charged ions. They combine with
negatively-charged ions to form salts.
Alkali Metals
• Table salt is made of sodium
ions and ions of the element
chlorine.
• In pure form, all of the alkali
metals have similar properties. For
example, they are so soft that
they can be cut easily with a knife.
• They have low densities and
melt at low temperatures. Cesium,
in fact, will melt on a hot day.
Alkaline Earth Metals
• The six elements in Group 2 are called
the alkaline earth metals.
• Alkaline earth metals are reactive, but
they are not as reactive as the alkali
metals.
• Alkaline earth metal atoms have two
electrons in the highest energy level.
• Like the alkali metals, they occur in
nature as ions combined with other
elements.
Alkaline Earth Metals
• Magnesium and calcium are common
alkaline earth metals.
• Calcium compounds make up much of
your bones and teeth.
• These elements are also used to make
building materials, such as cement.
• The shells of sea animals also contain
calcium.
• The compound magnesium hydroxide,
also called milk of magnesia, is used to
soothe upset stomachs.
Transition Metals
• Most transition metals are shiny.
• They have high melting points and are good
conductors of heat and electricity.
• Because of the arrangement of their outer
electrons, transition metals are much less reactive
than the alkali or alkaline earth metals.
• They can, however, combine with other elements.
Transition Metals
• Groups of transition metals share similar
properties.
• For example, iron, cobalt, and nickel are the
only metals with magnetic properties.
• Transition metals are often found in ores.
Ores are minerals containing relatively large
amounts of metal compounds.
Rare-Earth Metals
• The elements located in the two separate
rows at the bottom of the periodic table
are the rare-earth metals.
• The lanthanide series, elements 58-71 ,
follows lanthanum in Period 6.
• The actinide series, elements 90-103,
follows actinium in Period 7.
Rare-Earth Metals
• Except for element 61, all of the
lanthanides occur in nature.
• Most of the actinides, however, are
synthetic, or made in laboratories.
• All these elements are radioactive. The
most common and known element is
Uranium. Uranium is used as nuclear fuel
when its converted into plutonium, through
a nuclear reaction.
Check & Explain
pg. 193
Answer questions 1 & 2
8.3 Nonmetals & Metalloids
Objectives
1. Identify the groups containing
nonmetals and metalloids.
2. Explain why nonmetals have different
properties than metals.
3. List the nonmetals essential to life.
4. Communicate in a chart the different
properties of metals, nonmetals, and
metalloids.
Nonmetals & Metalloids
Did you know your life depends on nonmetals?
Look to the right of the zigzag line in the
periodic table - in Periods 2 and 3, locate
carbon, nitrogen, oxygen, sulfur, and
phosphorus.
These five nonmetals make
up much of your body.
Nonmetals & Metalloids
Together with hydrogen, they form fats,
carbohydrates, proteins, and nucleic acidsthe building blocks of living things.
Nonmetals & Metalloids
• Metalloids also play an important role in
daily life.
• For example, silicon is used to make
computer chips.
• These chips are used in computers,
watches, calculators, and even cars.
Properties of Nonmetals
and Metalloids
• Unlike metals, nonmetals do not have
luster and are poor conductors of heat
and electricity.
• Solid nonmetals are usually dull and
brittle.
• They are neither malleable nor ductile,
Many nonmetals are gases at room
temperature.
Properties of Nonmetals
and Metalloids
• Most nonmetals have many electrons in
their highest energy levels.
• They are held tightly by the nucleus and
not free to move around.
• The atoms of many nonmetals tend to
accept electrons from other
elements.
• Many form negatively-charged
ions.
Properties of Nonmetals
and Metalloids
• Metalloids have properties of both
metals and nonmetals.
• All the metalloids are shiny solids, but
they do not have as much luster as the
metals.
• Most conduct heat and electricity, but
not as well as metals.
Boron Group
• The only element in Group 13 that
is not a metal is boron.
• Boron is a brittle, black metalloid.
• It is used to make boric acid, a
mild antiseptic and laundry
products.
Boron Group
• Below Boron in the periodic
table is aluminum.
• Aluminum, metal has many uses
because it is light, soft, and easy
to cut. It also conducts heat and
electricity very well.
Boron Group
• Aluminum is the most abundant
metal in the earth's crust. However,
extracting aluminum from bauxite, its
major ore, requires great amounts of
energy.
Boron Group
• The other elements in the boron
group are the uncommon metals
gallium, indium, and thallium.
Carbon Group
• How is the lead in your pencil like a
diamond?
• Both are made of carbon.
• Carbon is the only nonmetal in Group
14.
• It has two common fo rms:
graphite and diamond. Graphite
makes up much of the "lead" in your
pencil.
Carbon Group
• Carbon is unique because it can
form an unlimited number of
different compounds.
• Most of the compounds found in
living things contain carbon.
Carbon Group
• Silicon and germanium are metalloids.
• The silicon compounds in rocks and soil
make up 60 percent of the earth's crust.
• Tin and lead are both metals. They are
both obtained from mining ore.
• "Tin" cans are steel food containers lined
with tin.
• Lead and its compounds are poisonous.
Nitrogen Group
• About 80 percent of the air
is nitrogen, a nonmetal in
Group 15.
• You breathe in nitrogen molecules
with every breath.
• Pure nitrogen is a gas that does not
combine easily with other elements.
Nitrogen Group
• Nitrogen is one of the elements
essential to life.
• Living things need nitrogen
compounds to make proteins.
• If its temperature is lowered to
-210o C, nitrogen gas becomes a
liquid.
Oxygen Group
• Oxygen, one of the most important
• elements on the earth, is also the most
abundant.
• It makes up about 20% of air,
60% of the mass of the human body,
and 50% of the mass of the earth's
crust.
• Oxygen is also produced by plants
during photosynthesis.
Oxygen Group
• Sulfur is a nonmetal.
• Major uses of sulfur include making
rubber and sulfuric acid.
• Selenium is a nonmetal that conducts
electricity in the presence of
sunlight.
• Because of this property, selenium is
used in light meters, solar cells, and
photocopiers.
Halogens
• The elements in Group 17 are called
halogens. Halogen means "salt-former.”
• Most of the food you eat contains a
halogen compound.
• Halogens combine with metals to form
salts.
• Sodium chloride, or table salt, is a
halogen compound.
• Your body needs sodium chloride to
conduct nerve impulses.
Halogens
• Fluorine is the most reactive of all
nonmetals.
• It comes from a mineral called
fluorspar.
• Fluoride toothpaste is made with
fluorine.
• It is also combined with other
nonmetals to make the nonstick
coatings on pans.
Halogens
• Chlorine, bromine, iodine, and
astatine are the other halogens.
• Chlorine is a green gas.
• Bromine is the only nonmetal that is
liquid at room temperature.
Nobel Gases
• Group 18 contains six colorless gases.
• They are called noble gases, because
they don't readily combine with
other elements.
• All the noble gases exist in the
earth's atmosphere.
• Neon and other noble gases can be
found in advertising signs.
Nobel Gases
• Helium is the second lightest gas.
• Since it is lighter than air, helium is
used to fill balloons and blimps.
Hydrogen
• Hydrogen is set apart from other
elements in the periodic table
because its properties do not fit any
single group.
• Although its physical properties
resemble those of helium, hydrogen
reacts easily with other elements.
• In some chemical reactions hydrogen
acts like a metal; in others it acts
like a nonmetal.
Check & Explain
pg. 199
Answer questions:
1, 2, & 3