Chapter 6
The Periodic Table
and Periodic Law
Section 6.1
Development of the
Modern Periodic Table
Objectives
• Trace the development and
Identify key features of the periodic
table.
History
• 1790s, French scientist Lavoisier
•23 elements
• 1800s: electricity and spectrometer
John Newlands
• Patterns of the periodic table
• Law of octaves
• Elements on the eights had similarities
Meyer & Mendeleev
• 1869-Meyer and Mendeleev:
connection between atomic mass and
properties
• Mendeleev published it first
– Left holes of undiscovered elements
– Predicted properties of undiscovered
elements- Sc, Ga, Ge
Moseley
• Problems with Mendeleev
•Rows by increasing atomic mass
• Moseley used atomic number instead
The Periodic Law
• There is a periodic repetition of
chemical and physical properties of
the element when they are arranged
by increasing atomic number.
The Modern Periodic Table
• Horizontal rows- periods
• Vertical columns- groups or families
• Groups 1A through 8A =
Representative Elements
– Wide range of chemical and physical
properties
• Groups 1B through 8B = Transition
Elements
Metals
– shiny, smooth
– solid room temperature
– good conductors of heat and
electricity
Alkali Metals
• Alkali Metals=
1A (excluding
hydrogen)
– highly reactive
Alkaline Earth Metals
• Alkaline Earth
Metals= 2A
– highly reactive (not
as much as 1A)
Transitions
• Transition metals
– Group B elements contained in the D
block of the table
• Inner transition metals
– the lanthanide and actinide series
– F block
Nonmetals
– Generally a gas or a brittle, dull-looking solids
– Poor conductors
• Halogens=7A
– REALLY REACTIVE
• Noble Gases= 8A
– unreactive and stable (all valence electrons are
filled)
Metalloids
–contain the physical and
chemical properties of both
metals and nonmetal
Homework
• Section 6.1 Assessment
–1-6 on page 158
Reactivity Trends
• Increases down the table for the metals
• Decreases down the table for the
nonmetals
Section 6.2
Classification of the
Elements
Objectives
• Explain why elements in the same
group have similar properties
• Identify the four blocks of the
periodic table based on electron
configuration
Valance Electrons
• The properties of each element in
each group are similar because they
have the same number of valence
electrons
Valence Electrons and
Period Number
• Energy level of valence electrons =
period on the table
• Example: Lithium: period 2, valence
electron in 2nd energy level (1s22s1)
Valence Electrons and
Group Number
• Group number (1A-8A) = number of
valence electrons
Putting it Together
• Oxygen is in the 3rd period and in
group 6A.
–Oxygen’s valence electrons are
located in the ____ energy level.
–Oxygen has ___ valence electrons.
S,P,D, and F Blocks
• 4 different energy sublevels:
s, p, d, and f
• S block= 1A and 2A
– holds max of 2 electrons
• P block= 3A through 8A
– max holds 6 electrons
– S block must fill before P block can fill
– Noble gases are stable because of filled
S and P blocks
S,P,D, and F Blocks
Continued…
• D block = transition metals
– max of 10 electron
• F block= inner transition metals
– unpredictable manner of filling
– max of 14 electrons
Reactivity Trends
• Increases down the table for the metals
• Decreases down the table for the
nonmetals
Homework
• Page 162, #10-15
Periodic Trends: Atomic
Radius
• For metals, atomic radius = ½
distance between adjacent nuclei in a
crystal element
• For nonmetals, atomic radius = ½
distance between nuclei of identical
atoms that are chemically bonded
Periodic Trends: Atomic
Radius
I
N
C
R
E
A
S
E
S
DECREASES
Atomic Radius
• The increase from top to bottom
is due to adding electron shells.
• The decrease from left to right is
due to increased nuclear charge
as you move to the right, which
draws electrons closer to the
nucleus.
Periodic Trends: Ionization
Energy
• Ionization energy= energy required
to remove an electron from a
gaseous atom
• Octet rule = atoms tend to gain lose
or share electrons to acquire a full
set of 8 valence electrons
Periodic Trends: Ionization
Energy
INCREASES
D
E
C
R
E
A
S
E
S
Periodic Trends:
Electronegativity
• Electronegativity= relative ability of
an atom to attract electrons in a
chemical bond.
Electronegativity
• Arbitrary units called Paulings (after
Linus Pauling) are used to express
electronegativity.
• Electronegativity increases from left
to right across a period and from top
to bottom down a group.
Periodic Trends:
Electronegativity
INCREASES
D
E
C
R
E
A
S
E
S