chapter: the periodic table -...
TRANSCRIPT
Chapter: The Periodic Table
Table of Contents
Section 3: Transition Elements
Section 1: Introduction to the
Periodic Table
Section 2: Representative Elements
Development of the Periodic Table–Mendeleev’s Table of Elements
Introduction to the Periodic Table
1
• By 1830, fifty-five different elements had
been isolated and named.
• In 1869, Mendeleev arranged elements in
order of increasing atomic mass and found
that elements with similar properties fell
into groups.
Introduction to the Periodic Table
1Development of the Periodic Table–Mendeleev’s Table of Elements
• Moseley improved the periodic table by
arranging the elements according to
atomic number instead of atomic mass.
Today’s Periodic Table
Introduction to the Periodic Table
1
• The modern periodic table contains 7
periods, or rows, of elements whose
properties change gradually and 18
groups, or columns, each with a family of
elements having similar properties.
Today’s Periodic Table
Introduction to the Periodic Table
1
Zones on the Periodic Table
Introduction to the Periodic Table
1
• Groups 1 and 2 along with groups 13 to 18
are called the representative elements.
Zones on the Periodic Table
Introduction to the Periodic Table
1
• Groups 3 to 12 are called the transition
elements (all metals).
Zones on the Periodic Table
Introduction to the Periodic Table
1
• Some transition elements, called the inner transition elements, are placed below the main table. These elements are calledthe lanthanide and actinide series because one series follows the element lanthanum, element 57, and the other series follows actinium, element 89.
• If you look at the periodic table, you will notice it is color coded.
Metals
Introduction to the Periodic Table
1
• The colors represent elements that are metals, nonmetals, or metalloids.
Metals
Introduction to the Periodic Table
1
• A metal has luster, conducts heat and
electricity, and is malleable and ductile.
– Luster – reflects light
– Malleable – hammered into sheets
– Ductile – pulled into wires
• Nonmetals are usually gases or brittle solids at room temperature and poor conductors of heat and electricity.
Nonmetals and Metalloids
Introduction to the Periodic Table
1
Nonmetals and Metalloids
Introduction to the Periodic Table
1
• There are only 17 nonmetals, but they include many elements that are essential for life—carbon, sulfur, nitrogen, oxygen, phosphorus, and iodine.
Nonmetals and Metalloids
Introduction to the Periodic Table
1
• A metalloid shares properties with metals
and nonmetals.
The Element Keys
Introduction to the Periodic Table
1
• Symbols are abbreviations often based on
the element’s name
1
Section Check
Question 1
Horizontal rows in the periodic table are
known as _______.
A. lines
B. periods
C. tables
D. walls
1
Section Check
Question 2
In 1869, this famous scientist invented the first
version of the periodic table of elements,
though there have been many changes since his
day.
1
Section Check
Answer
The scientist was Dmitri Mendeleev. Though
his name may not be as familiar to you as Isaac
Newton or Albert Einstein, Mendeleev is
arguably as important a figure in the history of
science.
1
Section Check
Question 3
What is the particular name given to groups 3
through 12 on the periodic table?
Answer
These groups are known as the transition
elements. On either side of them are the
representative elements.
Groups 1 and 2
Representative Elements
2
• Groups 1 and 2 are active metals found in
nature combined with other elements;
although hydrogen is placed in Group 1, it
is not a metal and shares properties with
Groups 1 and 17.
Alkali Metals
Representative Elements
2
• Alkali Metals (group 1) – silvery solids
with low densities and low melting points;
they increase in reactivity from top to
bottom of the periodic table.
Representative Elements
2Alkaline Earth Metals
• Alkaline-earth metals (Group 2) – are
denser, harder, have higher melting
points, and are slightly less reactive than
alkali metals in the same period.
Groups 13 through 18
Representative Elements
2
• Groups 13 through 18 may contain metals,
nonmetals, or metalloids in solid, liquid, or
gas form.
Group 13—The Boron Family
Representative Elements
2
• The boron family
elements in group 13 are
all metals except boron,
which is a metalloid;
these elements are used
in a variety of products.
• Cookware made with boron
can be moved directly from
the refrigerator into the
oven without cracking.
Group 13—The Boron Family
Representative Elements
2
• Aluminum is used to make soft-drink cans, cookware, siding for homes, and baseball bats.
• Gallium is a solid metal, but its melting point is so low that it will melt in your hand.
• It is used to make computer chips.
Group 14—The Carbon Group
Representative Elements
2
• The carbon group elements are all
metalloids or metals, except for carbon
itself.
Group 14—The Carbon Group
Representative Elements
2
• Carbon is found in all living things and
exists in several forms
– Graphite
– Diamond
– Coal
– Bucky balls
Group 14—The Carbon Group
Representative Elements
2
• Silicon and germanium are used in
electronics as semiconductors
Group 14—The Carbon Group• Tin and lead are the two heaviest
elements in Group 14.
Representative Elements
2
• Lead is used to protect your torso during dental X rays.
• It also is used in car batteries, low-milting alloys, protective shielding around nuclear reactors, and containers used for storing and transporting radioactive materials.
• Tin is used in pewter, toothpaste, and the coating on steel cans used for food.
Group 15—The Nitrogen Group
Representative Elements
2
• The nitrogen group contains nitrogen and
phosphorus, which are required by living
things and which are used in industry.
• About 80% of our air is
nitrogen.
Group 15—The Nitrogen Group
• The element phosphorus comes in two forms—white and red.
Representative Elements
2
• White phosphorus is so active it can’t be exposed to oxygen in the air or it will burst into flames.
• The heads of matches contain the less active red phosphorus, which ignites from the heat produced by friction when the match is struck.
Group 15—The Nitrogen Group
• Phosphorous compounds are essential ingredients for healthy teeth and bones.
Representative Elements
2
• Plants also need phosphorus, so it is one of the nutrients in most fertilizers.
Group 16—The Oxygen Family
Representative Elements
2
• The oxygen family contains oxygen and
sulfur, which are essential for life and used
to manufacture many products.
Group 16—The Oxygen Family
• Ozone, a less common form of oxygen, is formed in the upper atmosphere through the action of electricity during thunderstorms.
Representative Elements
2
• The presence of ozone is important because it shields living organisms from some harmful radiation from the Sun.
Group 16—The Oxygen Family
Representative Elements
2
• Selenium conducts electricity when exposed to light, so it is used in solar cells, lightmeters, and photographic materials.
Group 17—The Halogen Group
Representative Elements
2
• The halogen group elements form salts
with sodium and with the other alkali
metals.
• Halogen means
―salt former‖
Group 18—The Noble Gases
Representative Elements
2
• The noble gases rarely combine with other
elements, they are often used in lighting
and inflating balloons.
Uses for the Noble Gases
• The ―neon‖ lights you see in advertising signs can contain any of the noble gases, not just neon.
Representative Elements
2
• Electricity is passed through the glass tubes that make up the sign.
• Helium glows yellow, neon glows red-orange, and argon produces a bluish-violet color.
Uses for the Noble Gases
• Argon, the most abundant of the noble gases on Earth, was first found in 1894.
Representative Elements
2
• Krypton is used with nitrogen in ordinary lightbulbs because these gases keep the glowing filament from burning out.
• Krypton lights are used to illuminate landing strips at airports, and xenon is used in strobe lights and was once used in photographic flash cubes.
Uses for the Noble Gases
• At the bottom of the group is radon, a radioactive gas produced naturally as uranium decays in rocks and soil.
Representative Elements
2
• If radon seeps into a home, the gas can be harmful because it continues to emit radiation.
• When people breathe the gas over a period of time, it can cause lung cancer.
2
Section Check
Answer
Halogen means “salt-
former.” All the
halogens form salts with
sodium (and other alkali
metals).
2
Section Check
Question 2
Why is it important to have a layer of ozone in
our upper atmosphere?
Answer
Ozone shields us from dangerous forms of
radiation that come from the Sun.
2
Section Check
Question 3
Almost 80% of the air you are breathe consists
of _______.
A. oxygen
B. nitrogen
C. halothane
D. argon
2
Section Check
Answer
The answer is B. Most people think they are
just breathing oxygen, but in fact they are
mostly breathing in nitrogen!
The Metals in the Middle
Transition Elements
3
• Groups 3 to 12 are the transition elements;
most are combined with other elements in
ores.
The Iron Triad
Transition Elements
3
• The iron triad is composed of iron, cobalt,
and nickel; these metals have magnetic
properties.
The Iron Triad
• Industrial magnets are made from an alloy of nickel, cobalt, and aluminum.
Transition Elements
3
• Nickel is used in batteries along with cadmium.
• Iron is a necessary part of hemoglobin, the substance that transports oxygen in the blood.
• Iron also is mixed with other metals and with carbon to create a variety of steels with different properties.
Platinum group
• Ruthenium, rhodium, palladium, osmium,
indium, and platinum are part of the
platinum group.
Uses of Transition Elements
Transition Elements
3
• Tungsten has the highest melting point of any metal (3,410°C) and will not melt when a current passes through it.
• The filaments of lightbulbs are made oftungsten,
element 74.
Uses of Transition Elements• Mercury, which has the lowest melting point
of any metal (–39°C), is used in thermometers and in barometers.
Transition Elements
3
• Mercury is the only metal that is a liquid at room temperatures.
• Like many of the heavy metals, mercury is poisonous to living beings.
Uses of Transition Elements
• Chromium’s name comes from the Greek word for color, chrome.
Transition Elements
3
• Many other transition elements combine to form substances with brilliant colors.
Uses of Transition Elements
Transition Elements
3
• Several transition elements can be used
as catalysts, which are substances that
make reactions occur faster without
changing itself.
Inner Transition Elements
• The inner transition elements are called lanthanides and actinides.
Transition Elements
3
• The first series, from cerium to lutetium, is called the lanthanides.
• The second series of elements, from thorium to lawrencium, is called the actinides.
The Lanthanides
Transition Elements
3
• The lanthanides are soft metals and were
once thought to be rare.
The Actinides
Transition Elements
3
• Uranium is found in Earth’s crust because its half-life is long—4.5 billion years.
• All the actinides are radioactive; several
are synthetic elements that do not occur
naturally.
The Actinides
Transition Elements
3
• Plutonium is used as a fuel in nuclear power plants.
• Americium is used in some home smoke detectors.
• Californium-252 is used to kill cancer cells.
Dentistry and Dental Materials
• Dentists have been using amalgam for over 150 years to fill cavities in decayed teeth.
Transition Elements
3
• Amalgam, a mixture of silver, copper, tin, and mercury, is the familiar ―silver filling.‖
Dentistry and Dental Materials
• Because amalgam contains mercury, some people are concerned that the use of this particular type of filling may unnecessarily expose a person to mercury vapor.
Transition Elements
3
Dentistry and Dental Materials
Transition Elements
3
• Dental materials are sometimes made of
new composites, resins, and porcelins.
Section Check
3
Which three elements are known as “the iron
triad”?
Question 1
The iron triad consists of iron, cobalt, and
nickel. They are called this because of their
similar properties.
Answer
Section Check
3
Which group consists of ruthenium, rhodium,
palladium, osmium, iridium, and platinum?
Question 2
The answer is the platinum group. These
elements all have similar properties, which
is why they are grouped together.
Answer
Section Check
3
What is most notable about the nuclei of the
actinides?
Question 3
The nuclei of actinides are unstable. All the
actinides are radioactive, which means they
decay to form other elements.
Answer