Drill
Determine the group and period of the
following:

a.
b.
c.
Mg
Ar
N
Objective

SWBAT:

Explore the arrangement of the periodic table in
order to identify its trends.
SAT/HSA Enrichment

Male fiddler crabs attract females by quickly waving
their large front claw. If a claw is lost in a fight or
accident, they quickly grow a hollow claw of equal
length. Because the new claw is lighter, they can
wave it faster.

a.
b.
c.
d.
The new claw probably helps the male fiddler crab to
successfully reproduce
maintain homeostasis
fight more successfully
evolve into a new species
Engagement

Draw two graphs on the board




one of a direct relationship
one of an inverse relationship
In each case show a line of best fit and points
that are not directly on the line.
Can someone describe the relationship
between variables in each graph.
Engagement



Why are there some points not directly on the
line?
Reinforce the idea of general trends that
graphs reveal.
Trends of these two types are what you are
going to see today as you complete your quick
lab later in class.
Periodic Trends
Trends on the Periodic Table!
Periodic Trends

Sodium chloride (table
salt) produced the
geometric pattern in the
photograph. Such a pattern
can be used to calculate
the position of nuclei in a
solid. You will learn how
properties such as atomic
size are related to the
location of elements in the
periodic table.
Trends in Atomic Size

The atomic radius is one half of the distance
between the nuclei of two atoms of the same
element when the atoms are joined.
Trends in Atomic Size

Group and Periodic Trends in Atomic Size

In general, atomic size increases from top to
bottom within a group and decreases from left
to right across a period.
Trends in Atomic Size
Trends in Atomic Size
Ions

Positive and negative ions form when
electrons are transferred between atoms.
Ions
Positive and negative ions form when
electrons are transferred between atoms.

Ions

Some compounds are composed of particles
called ions.



An ion is an atom or group of atoms that has a
positive or negative charge.
A cation is an ion with a positive charge.
An anion is an ion with a negative charge.
Trends in Ionization Energy

The energy required to remove an electron
from an atom is called ionization energy.


The energy required to remove the first electron
from an atom is called the first ionization
energy.
The energy required to remove an electron from
an ion with a 1+ charge is called the second
ionization energy.
Trends in Ionization Energy

Group and Periodic Trends in Ionization
Energy

First ionization energy tends to decrease from
top to bottom within a group and increase from
left to right across a period.
Trends in Ionization Energy
Trends in Ionization Energy
Trends in Ionization Energy
Trends in Ionic Size

Trends in Ionic Size

During reactions between metals and nonmetals,
metal atoms tend to lose electrons, and nonmetal
atoms tend to gain electrons. The transfer has a
predictable effect on the size of the ions that
form.
Trends in Ionic Size


Cations are always smaller than the
atoms from which they form.
Anions are always larger than the
atoms from which they form.
Trends in Ionic Size

Relative Sizes of Some Atoms and Ions
Trends in Ionic Size
Size generally increases

Trends in Ionic Size
Trends in Electronegativity

Trends in Electronegativity


Electronegativity is the ability of an atom of an
element to attract electrons when the atom is in
a compound.
In general, electronegativity values decrease
from top to bottom within a group. For
representative elements, the values tend to
increase from left to right across a period.
Trends in Electronegativity

Representative Elements in Groups 1A through 7A
Summary of Trends

The trends that exist among these
properties can be explained by
variations in atomic structure.
Summary of Trends
Increases Decreases
Size
Electronegativity
Ionic
Atomic
Nuclear
Shielding
Ionization
of
size
cations
Size
anions
Charge
energy
Increases
Decreases
Constant
Short Quiz
1.
Which of the following sequences is correct for
atomic size?
a.
b.
c.
d.
Mg > Al > S
Li > Na > K
F>N>B
F > Cl > Br
Short Quiz
2.
Metals tend to
a.
b.
c.
d.
gain electrons to form cations.
gain electrons to form anions.
lose electrons to form anions.
lose electrons to form cations.
Short Quiz
3.
Which of the following is the most
electronegative?
a.
b.
c.
d.
Cl
Se
Na
I
Graphing

Graphing Physical Properties

Purpose

Make a graph of physical properties versus atomic
number and use the graph to identify periodic and group
trends.
Periodic Trends


Periodic Trends worksheet.
Review the worksheet.
Summary




Was the objective accomplished? Explain.
How can you compare the different trends
within the periodic table?
Devise a way to remember the trends of the
periodic table.
Explain the importance of the trends of the
periodic table.
Homework

Study for your Atomic Structure Assessment


Take home your notebooks.
Complete any make up work!

Due next class.