Transcript Elements and the Periodic Table

Elements and the Periodic Table
Book K
Table of Contents
Introduction to Atoms
Organizing the Elements
Metals
Ch. 3 – Sec. 1: Pg. 74-79
Ch. 3 – Sec. 2: Pg. 80-87
Ch. 3 – Sec. 3: Pg. 88-95
Nonmetals and Metalloids
Ch. 3 – Sec. 4: Pg. 98-105
Radioactive Elements
Ch. 4 – Sec. 4: Pg. 139-146
Elements and the Periodic Table - Introduction to Atoms
Structure of an Atom
• Atoms are made of even smaller particles called protons,
neutrons, and electrons.
• Protons and neutrons are located in the nucleus.
• Electrons move rapidly around the nucleus.
• Charges:
• Protons (+)
• Neutrons (0)
• Electrons (-)
Elements and the Periodic Table - Introduction to Atoms
Models of Atoms
• For over two centuries, scientists have created models of
atoms in an effort to understand why matter behaves
as it does. As scientists have learned more, the model of
the atom has changed.
Elements and the Periodic Table - Introduction to Atoms
Atoms and Elements
•
•
•
•
•
Each element consists of atoms that
differ from the atoms of all other elements.
An element can be identified by the
number of protons in the nucleus of its
atoms.
Every atom of an element has the same
number of protons.
Because atoms are so small, scientists
create models to describe them.
A model may be a diagram, a mental
picture, a mathematical statement, or an
object that helps explain ideas about
the natural world.
•Atomic number –
number of protons in the
nucleus of an atom.
•Mass number – the sum
of protons and neutrons in
the nucleus of an atom.
•Atoms with the same
number of protons and
different number of
neutrons are called
isotopes.
Elements and the Periodic Table - Introduction to Atoms
Isotopes
• Atoms of all isotopes of carbon contain six protons, but
they differ in the number of neutrons. Carbon-12 is the
most common isotope.
Elements and the Periodic Table - Introduction to Atoms
Previewing Visuals
Before you read, preview Figure 2. Then write two questions
that you have about the diagram in a graphic organizer like
the one below. As you read, answer your questions.
Structure of an Atom
Q. What particles are in the center of the atom?
A. Protons and neutrons
Q. What particles move around the outside of the nucleus?
A. Electrons
Elements and the Periodic Table - Introduction to Atoms
More on Atoms
Click the PHSchool.com button for an activity about atoms.
Elements and the Periodic Table
End of Section:
Introduction to
Atoms
Elements and the Periodic Table - Organizing the Elements
Patterns in the Elements
• Dimitri Mendeleev, a Russian scientist,
discovered a set of patterns that applied to
elements.
• He noticed that a pattern of properties
appeared when he arranged the elements in
order of increasing atomic mass.
• Atomic mass – the average mass of all the
isotopes of that element.
• Henry Moseley, a British scientist, discovered
atomic number, so now we arrange the periodic
table by atomic number.
• In the periodic table used today, the properties
of elements repeat in each period (row) of
the table.
Elements and the Periodic Table - Organizing the Elements
Finding Data on Elements
• Each square of the periodic table includes an element’s
atomic number, chemical symbol, name, and atomic mass.
Elements and the Periodic Table - Organizing the Elements
Periodic Table Activity
Click the Active Art button to open a browser window and
access Active Art about the periodic table.
Elements and the Periodic Table - Organizing the Elements
Organization of the Periodic Table
The 18 columns of the periodic table reflect a repeating
pattern of properties that generally occur across a period.
Elements and the Periodic Table - Organizing the Elements
Organization of the Periodic Table
• The properties of an element can be
predicted from its location in the
periodic table.
• Periods – horizontal rows.
• As you move from left to right,
properties of the elements change
according to pattern.
• Groups (families) – vertical columns.
• The groups are numbered, from
Group 1 on the left to Group 18 of
the right.
• The elements in group have similar
characteristics.
Elements and the Periodic Table - Organizing the Elements
Asking Questions
Before you read, preview the red headings. In a graphic
organizer like the one below, ask a what or how question for
each heading. As you read, write answers to your questions.
Question
Answers
What pattern of elements did
Mendeleev discover?
Patterns appeared when the
elements were arranged in order
of increasing atomic mass.
What data about elements is
found in the periodic table?
Atomic number, chemical
symbols and names, and
average atomic mass
How are elements organized
in the periodic table?
Elements are organized in
periods and groups based on
their properties.
Elements and the Periodic Table
End of Section:
Organizing the
Elements
Elements and the Periodic Table - Metals
Properties of Metals
• The physical properties of metals include
shininess, malleability, ductility, and
conductivity.
• A malleable material is one that can be
hammered or rolled into flat sheets or
other shapes.
• A ductile material is one that can be
pulled out, or drawn, into long wire.
• Conductivity is the ability of an object to
transfer heat or electricity to another
object.
Elements and the Periodic Table - Metals
Properties of Metals
• The chemical property, reactivity, is
the ease and speed with which an
element combines or reacts with other
elements or compounds.
• The gradual wearing away of a
metal element due to a chemical
reaction is corrosion.
• The reactivity of metals tends to
decrease as you move from left to
right across the periodic table.
Elements and the Periodic Table - Metals
Metals in the Periodic Table
• The metals in Group 1, from lithium to francium,
are called the alkali metals. Alkali metals react
with atoms of other elements by losing one
electron.
Elements and the Periodic Table - Metals
Metals in the Periodic Table
• Group 2 of the periodic table contains the
alkaline earth metals. These elements are
not as reactive as the metals in Group 1, but they
are more reactive than most other metals.
Elements and the Periodic Table - Metals
Melting Points in a Group of Elements
The properties of elements
within a single group in the
periodic table often vary in a
certain pattern. The following
graph shows the melting points
of Group 1 elements (alkali
metals) from lithium to francium.
Elements and the Periodic Table - Metals
Melting Points in a Group of Elements
Reading Graphs:
As you look at Group 1 from
lithium to francium, describe
how the melting points of the
alkali metals change.
Melting points decrease from
lithium to francium.
Elements and the Periodic Table - Metals
Melting Points in a Group of Elements
Predicting:
If element number 119 were
synthesized, it would fall
below francium in Group 1 of
the periodic table. Predict the
approximate melting point of
new element 119.
New element 119 should
have a melting point of
approximately 25ºC.
Elements and the Periodic Table - Metals
Melting Points in a Group of Elements
Interpreting Data:
Room temperature is usually
about 22ºC. Human body
temperature is 27ºC. Which of
the alkali metals are liquids at
room temperature? Which might
melt if you could hold them in
your hand?
None of the alkali metals are
liquids at room temperature.
Cesium and francium might melt
if you could hold them in your
hand.
Elements and the Periodic Table - Metals
Metals in the Periodic Table
• The transition metals are less reactive than the metals in
Groups 1 and 2.
• Ex. iron, copper, nickel, silver, and gold
Elements and the Periodic Table - Metals
Metals in the Periodic Table
• Only some of the elements in Groups 13 through 15 of
the periodic table are metals. These metals are not nearly
as reactive as those on the left side of the table.
• Ex. aluminum, tin, lead
Elements and the Periodic Table - Metals
Metals in the Periodic Table
• Lanthanides are soft, malleable, shiny metals with high
conductivity.
• They are mixed with more common metals to produce
alloys, which are a mixture of metal with one other
element, usually another metal.
Elements and the Periodic Table - Metals
Metals in the Periodic Table
• The elements below the lanthanides are called actinides.
Many of these elements are so unstable that they last for
only a fraction of a second after they are made.
Elements and the Periodic Table - Metals
Synthetic Elements
• Elements with atomic numbers higher
than 92 are sometimes described as
synthetic elements because they are not
found naturally on Earth.
• Instead, elements that follow uranium are
made – or synthesized – when nuclear
particles are forced to crash into one
another.
• To make even heavier elements (with
atomic numbers above 95), scientists use
powerful machines called particle
accelerators which move atomic nuclei
faster and faster until they reach very high
speeds and then crash into each other.
Elements and the Periodic Table - Metals
Using Prior Knowledge
Before you read, write what you know about metals in a
graphic organizer like the one below. As you read, write what
you learn.
What You Know
1.
2.
Metals are shiny.
Some metals are magnetic.
What You Learned
1.
2.
Ductile metals can be pulled into a wire.
Alkali metals react by losing one electron.
Elements and the Periodic Table - Metals
Links on Metals
Click the SciLinks button for links on metals.
Elements and the Periodic Table
End of Section:
Metals
Elements and the Periodic Table - Nonmetals and Metalloids
Properties of Nonmetals
• A nonmetal is an element that lacks
most of the properties of a metal.
• Most nonmetals are poor
conductors of electricity and heat
and are reactive with other elements.
• Solid nonmetals are dull and brittle.
• Many of the nonmetals are common
elements on Earth.
• Ex. nitrogen, oxygen, carbon,
iodine, sulfur, bromine
Elements and the Periodic Table - Nonmetals and Metalloids
Properties of Nonmetals
• When nonmetals react with metals, one or more
electrons move from the metal atoms to the nonmetal
atoms.
Elements and the Periodic Table - Nonmetals and Metalloids
Families of Nonmetals
• Each element in the carbon family has atoms
that can gain, lose, or share four electrons when
reacting with atoms of other elements.
Elements and the Periodic Table - Nonmetals and Metalloids
Families of Nonmetals
• Group 15, the nitrogen family, contains two nonmetals:
nitrogen and phosphorus. These non-metals usually gain
or share three electrons when reacting with atoms of
other elements.
• Nitrogen is an example of an element that occurs in
nature in the form of diatomic molecules, as N2.
• A diatomic molecule consists of two atoms.
Elements and the Periodic Table - Nonmetals and Metalloids
Families of Nonmetals
• Group 16, the oxygen family, contains three
nonmetals: oxygen, sulfur, and selenium. These
elements usually gain or share two electrons
when reacting with atoms of other elements.
Elements and the Periodic Table - Nonmetals and Metalloids
Families of Nonmetals
• The Group 17, the halogens, are the most reactive
nonmetals. Atoms of these elements easily form
compounds by sharing or gaining one electron when
reacting with atoms of other elements.
Elements and the Periodic Table - Nonmetals and Metalloids
Families of Nonmetals
• The elements in Group 18 are known as the
noble gases. They do not ordinarily form
compounds because atoms of noble gases do not
usually gain, lose, or share electrons.
Elements and the Periodic Table - Nonmetals and Metalloids
Families of Nonmetals
• Because the chemical properties of hydrogen differ very
much from those of the other elements, it really cannot be
grouped into a family.
Elements and the Periodic Table - Nonmetals and Metalloids
The Metalloids
• The metalloids have some characteristics of both metals and
nonmetals. The most useful property of the metalloids is their
varying ability to conduct electricity.
• Semiconductors are substances that can conduct electricity.
• They are used to make computer chips, transistors, and
lasers.
Elements and the Periodic Table - Nonmetals and Metalloids
Using Prior Knowledge
Before you read, write what you know about nonmetals in a
graphic organizer like the one below. As you read, write what
you learn.
What You Know
1.
2.
Nonmetals are not shiny.
Nonmetals are not magnetic.
What You Learned
1.
2.
Nonmetals are dull and brittle.
Metalloids have characteristics of metals and
nonmetals.
Elements and the Periodic Table - Nonmetals and Metalloids
Links on Nonmetals
Click the SciLinks button for links on nonmetals.
Elements and the Periodic Table
End of Section:
Nonmetals and
Metalloids
Elements and the Periodic Table
Graphic Organizer
Periodic table
is made up of
organizes
Elements
Rows
Columns
in order of increasing
called
called
Atomic
number
Periods
Families
and shows
or
Patterns of
properties
Groups
Elements and the Periodic Table
End of Section:
Graphic Organizer
Elements and the Periodic Table
Radioactivity
• Remember…..the number of protons determines the
identity of an atom
Ex: Carbon = 6
Oxygen = 8
• Nuclear reaction - reaction involving the particles in the
nucleus of an atom
• Unlike a chemical reaction which only involves an
atom’s electrons
• Isotope - atoms with the same number of protons and
different numbers of neutrons
• Some are unstable if the nuclei do not hold together well
• Radioactive decay - the atomic nuclei of unstable
isotopes release fast-moving particles and energy
• Ex: Uranium, polonium, radium
Elements and the Periodic Table
Radioactivity
• Marie Curie, Pierre Curie, and Henri Becquerel studied
uranium after noticing spontaneous energy release on
a photographic plate.
• The reaction was occurring within the uranium nuclei
• Radioactivity- spontaneous emission of radiation by an
unstable atomic nucleus
• M. Curie further discovered two new elements which
gave off radioactive energy as well, Polonium and
Radium.
Elements and the Periodic Table
Radioactive decay
• Natural radioactive decay can produce alpha
particles, beta particles, and gamma rays.
• Alpha decay - a nucleus loses an alpha particle,
which consists of two protons and two neutrons.
Elements and the Periodic Table
Radioactive decay
• Beta decay - a neutron inside an unstable nucleus
changes into a beta particle and a proton.
• Beta particle - fast-moving electron given off by a
nucleus during radioactive decay
Elements and the Periodic Table
Radioactive decay
• Gamma radiation - has no charge and does not
cause a change in either the atomic mass or the
atomic number.
• Consists of high-energy waves.
Elements and the Periodic Table
Radioactive decay
• The three types of nuclear radiation were named
based on how easily each one could be blocked.
• Alpha, beta, and gamma are the first three letters of
the Greek alphabet.
Elements and the Periodic Table
Radioactive dating
• Half-life - the length of time needed for half of the
atoms of a sample to decay
• Each isotope has its own unique half-life
• From the amount of an isotope in a fossil, scientists
can calculate how many half-lives have passed since
the organism was alive. They are then able to
estimate the age of the fossil and the surrounding
rock.
• Radioactive dating - the process of determining the
age of an object using the half-life of one or more
radioactive isotopes.
Elements and the Periodic Table
Radioactive dating
• The half-lives of
radioactive isotopes
range from a fraction of
a second to billions of
years.
Elements and the Periodic Table
Radioactive dating
• Because radioactive isotopes can change into
different matter and can give off detectable
radiation, they are used in:
• Determining the ages of natural materials on Earth
• Tracing the steps of chemical reactions and
industrial processes
• Diagnosing and treating disease
• Providing sources of energy
Elements and the Periodic Table
Using Radioactive Isotopes
• Tracers – radioactive
isotopes that can be
followed through the steps
of a chemical reaction or
industrial process.
• Used in studying
reactions in living
organisms.
Elements and the Periodic Table
Radioactive Tracers Activity
Click the Active Art button to open a browser window and
access Active Art about radioactive tracers.
Elements and the Periodic Table
Using Radioactive Isotopes
Medicine:
• Can make images of
the bone, blood vessel
or organ affected
• Used to destroy
unhealthy cells (iodine131 for thyroid tumors)
Nuclear Power:
• Fuel- can provide
electric energy
Elements and the Periodic Table
Dangers of Radiation
• Radiation can:
• Penetrate living tissue and
interfere with chemical reactions
in living cells
• Cause illness, disease, and even
death from overexposure
• Protection includes:
• Wearing protective clothing and
insulating shields
• Properly disposing of wastes
Elements and the Periodic Table
Radiation
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