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CHEMISTRY
Matter and Change
Chapter 6: The Periodic Table and
Periodic Law
CHAPTER
6
Table Of Contents
Section 6.1
Development of the Modern
Periodic Table
Section 6.2
Classification of the Elements
Section 6.3
Periodic Trends
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SECTION
6.1
Development of the Modern Periodic Table
• Trace the development of the periodic table.
• Identify key features of the periodic table.
atomic number: the number of protons in an atom
The periodic table evolved over time as
scientists discovered more useful ways to
compare and organize the elements.
SECTION
6.1
Development of the Modern Periodic Table
periodic law
group
period
representative elements
transition elements
metal
alkali metals
alkaline earth metals
transition metal
inner transition metal
lanthanide series
actinide series
nonmetals
halogen
noble gas
metalloid
SECTION
6.1
Development of the Modern Periodic Table
Development of the Periodic Table
• In the 1700s, Lavoisier compiled a list of all
the known elements of the time.
SECTION
6.1
Development of the Modern Periodic Table
Development of the Periodic Table (cont.)
• The 1800s brought large amounts of
information and scientists needed a way to
organize knowledge about elements.
• John Newlands proposed an arrangement
where elements were ordered by increasing
atomic mass.
SECTION
6.1
Development of the Modern Periodic Table
Development of the Periodic Table (cont.)
• Newlands noticed
when the elements
were arranged by
increasing atomic
mass, their
properties repeated
every eighth
element.
SECTION
6.1
Development of the Modern Periodic Table
Development of the Periodic Table (cont.)
• Meyer and Mendeleev both demonstrated
a connection between atomic mass and
elemental properties.
• Moseley rearranged the table by increasing
atomic number, and resulted in a clear
periodic pattern.
• * is called periodic law.
SECTION
6.1
Development of the Modern Periodic Table
Development of the Periodic Table (cont.)
SECTION
6.1
Development of the Modern Periodic Table
The Modern Periodic Table
• The modern periodic table contains boxes
which contain the element's name, symbol,
atomic number, and atomic mass.
SECTION
6.1
Development of the Modern Periodic Table
The Modern Periodic Table (cont.)
• * are called groups.
• * are called periods.
• Elements in groups 1,2, and 13-18 possess a
wide variety of chemical and physical
properties and are called the representative
elements.
• * are known as the transition metals.
SECTION
6.1
Development of the Modern Periodic Table
The Modern Periodic Table (cont.)
• Elements are classified as metals, non-metals,
and metalloids.
• Metals are elements that are generally shiny
when smooth and clean, solid at room
temperature, and good conductors of heat and
electricity.
• Alkali metals are all the elements in *
• Alkaline earth metals are in *
SECTION
6.1
Development of the Modern Periodic Table
The Modern Periodic Table (cont.)
• The transition elements are divided into
transition metals and inner transition
metals.
• The two sets of inner transition metals are
called the lanthanide series and actinide
series and are located at the bottom of the
periodic table.
SECTION
6.1
Development of the Modern Periodic Table
The Modern Periodic Table (cont.)
• Non-metals are elements that are
generally *
• Group 17 is composed of highly reactive
elements called halogens.
• Group 18 gases are extremely unreactive and
commonly called noble gases.
SECTION
6.1
Development of the Modern Periodic Table
The Modern Periodic Table (cont.)
• Metalloids have physical and chemical
properties of both metals and non-metals,
such as silicon and germanium.
SECTION
6.1
Development of the Modern Periodic Table
The Modern Periodic Table (cont.)
SECTION
6.2
Classification of the Elements
• Explain why elements in
the same group have
similar properties.
• Identify the four blocks
of the periodic table
based on their electron
configuration.
valence electron:
electron in an atom's
outermost orbitals;
determines the chemical
properties of an atom
Elements are organized into different
blocks in the periodic table according
to their electron configurations.
SECTION
6.2
Classification of the Elements
Organizing the Elements by Electron
Configuration
• Recall electrons in the highest principal energy
level are called valence electrons.
• All group 1 elements have one valence
electron.
SECTION
6.2
Classification of the Elements
Organizing the Elements by Electron
Configuration (cont.)
• The energy level of an element’s valence
electrons indicates the period on the
periodic table in which it is found.
• The number of valence electrons for
elements in groups 13-18 is ten less than
their group number.
SECTION
6.2
Classification of the Elements
Organizing the Elements by Electron
Configuration (cont.)
SECTION
6.2
Classification of the Elements
The s-, p-, d-, and f-Block Elements
• The shape of the periodic table becomes clear
if it is divided into blocks representing the
atom’s energy sublevel being filled with
valence electrons.
SECTION
6.2
Classification of the Elements
The s-, p-, d-, and f-Block Elements (cont.)
• s-block elements consist of group 1 and 2,
and the element helium.
• Group 1 elements have a partially filled s
orbital with one electron.
• Group 2 elements have a completely filled s
orbital with two electrons.
SECTION
6.2
Classification of the Elements
The s-, p-, d-, and f-Block Elements (cont.)
• After the s-orbital is filled, valence
electrons occupy the p-orbital.
• Groups 13-18 contain elements with
completely or partially filled p orbitals.
SECTION
6.2
Classification of the Elements
The s-, p-, d-, and f-Block Elements (cont.)
• The d-block contains the transition metals
and is the largest block.
• There are exceptions, but d-block elements
usually have filled outermost s orbital, and
filled or partially filled d orbital.
• The five d orbitals can hold 10 electrons, so
the d-block spans ten groups on the periodic
table.
SECTION
6.2
Classification of the Elements
The s-, p-, d-, and f-Block Elements (cont.)
• The f-block contains the inner transition
metals.
• f-block elements have filled or partially filled
outermost s orbitals and filled or partially filled
4f and 5f orbitals.
• The 7 f orbitals hold 14 electrons, and the
inner transition metals span 14 groups.
SECTION
6.3
Periodic Trends
• Compare period and
group trends of several
properties.
• Relate period and group
trends in atomic radii to
electron configuration.
principal energy level:
the major energy level of
an atom
ion
ionization energy
octet rule
electronegativity
Trends among elements in the periodic
table include their size and their ability to
lose or attract electrons
SECTION
6.3
Periodic Trends
Atomic Radius
• Atomic size is a periodic trend influenced
by electron configuration.
• For metals, atomic radius is half the distance
between adjacent nuclei in a crystal of the
element.
SECTION
6.3
Periodic Trends
Atomic Radius (cont.)
• For elements that occur as molecules, the
atomic radius is half the distance between
nuclei of identical atoms.
SECTION
6.3
Periodic Trends
Atomic Radius (cont.)
• There is a general decrease in atomic
radius from left to right, caused by
increasing positive charge in the nucleus.
• Valence electrons are not shielded from the
increasing nuclear charge because no
additional electrons come between the
nucleus and the valence electrons.
SECTION
6.3
Periodic Trends
Atomic Radius (cont.)
SECTION
6.3
Periodic Trends
Atomic Radius (cont.)
• Atomic radius generally *.
• The outermost orbital size *.
SECTION
Periodic Trends
6.3
Ionic Radius
• An ion is *
• When atoms lose electrons and form positively
charged ions, they always become smaller for
two reasons:
1. The loss of a valence electron can leave an empty
outer orbital resulting in a small radius.
2. Electrostatic repulsion decreases allowing the
electrons to be pulled closer to the radius.
SECTION
6.3
Periodic Trends
Ionic Radius (cont.)
• When atoms gain electrons, they can
become larger, because the addition of an
electron increases electrostatic repulsion.
SECTION
6.3
Periodic Trends
Ionic Radius (cont.)
• The ionic radii of positive ions generally
decrease from left to right.
• The ionic radii of negative ions generally
decrease from left to right, beginning with group
15 or 16.
SECTION
6.3
Periodic Trends
Ionic Radius (cont.)
• Both positive and negative ions increase in
size moving down a group.
SECTION
6.3
Periodic Trends
Ionization Energy
• Ionization energy is defined as *
• The energy required to remove the first
electron is called the first ionization energy.
SECTION
6.3
Periodic Trends
Ionization Energy (cont.)
SECTION
6.3
Periodic Trends
Ionization Energy (cont.)
• Removing the second electron requires more
energy, and is called the second ionization
energy.
• Each successive ionization requires more
energy, but it is not a steady increase.
SECTION
6.3
Periodic Trends
Ionization Energy (cont.)
SECTION
6.3
Periodic Trends
Ionization Energy (cont.)
• The ionization at which the large increase
in energy occurs is related to the number of
valence electrons.
• First ionization energy increases from left to
right across a period.
• First ionization energy decreases down a
group because atomic size increases and
less energy is required to remove an electron
farther from the nucleus.
SECTION
6.3
Periodic Trends
Ionization Energy (cont.)
SECTION
6.3
Periodic Trends
Ionization Energy (cont.)
• The octet rule states that *.
• The octet rule is useful for predicting what
types of ions an element is likely to form.
SECTION
6.3
Periodic Trends
Ionization Energy (cont.)
• The electronegativity of an element indicates
its relative ability to *
• Electronegativity decreases down a group
and increases left to right across a period.
SECTION
6.3
Periodic Trends
Ionization Energy (cont.)
SECTION
6.1
Development of the Modern Periodic Table
Study Guide
Key Concepts
• The elements were first organized by increasing
atomic mass, which led to inconsistencies. Later,
they were organized by increasing atomic number.
• The periodic law states that when the elements are
arranged by increasing atomic number, there is a
periodic repetition of their chemical and physical
properties.
• The periodic table organizes the elements into periods
(rows) and groups (columns); elements with similar
properties are in the same group.
SECTION
6.1
Development of the Modern Periodic Table
Study Guide
Key Concepts
• Elements are classified as either metals, nonmetals,
or metalloids.
SECTION
6.2
Classification of the Elements
Study Guide
Key Concepts
• The periodic table has four blocks (s, p, d, f).
• Elements within a group have similar chemical
properties.
• The group number for elements in groups 1 and 2
equals the element’s number of valence electrons.
• The energy level of an atom’s valence electrons equals
its period number.
Periodic Trends
SECTION
6.3
Study Guide
Key Concepts
• Atomic and ionic radii decrease from left to right across
a period, and increase as you move down a group.
• Ionization energies generally increase from left to right
across a period, and decrease as you move down a
group.
• The octet rule states that atoms gain, lose, or share
electrons to acquire a full set of eight valence electrons.
• Electronegativity generally increases from left to right
across a period, and decreases as you move down a
group.