7th Grade
7th Grade Science
PISD PowerPoint Lessons
Developed By
Ryan Gross, Park Crest Middle School
Edited By
Kenn Heydrick, Coordinator of Science & Health
Chapter 3 - Understanding the
Periodic Table
Section 1:
Electrons and the Periodic
Table
Section 2:
Grouping the Elements
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Why Do I Need the Periodic Table?
What Do You Think?
What does your outer
shell of clothing say to
other people about you
and who you are?
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Electrons & the Periodic Table
Electrons in all
atoms are arranged
around the nucleus
in regions called
energy levels
Energy Levels
© Fall 2005, Pflugerville ISD, 8th Grade
•The largest atoms
have as many as
seven energy levels
Unit A: Chapter 3
Electrons & the Periodic Table
The outermost
energy level is
called the valence
shell
Energy Levels
© Fall 2005, Pflugerville ISD, 8th Grade
The electrons in the
valence shell are
called valence
electrons
Unit A: Chapter 3
Electrons & the Periodic Table
Elements are grouped because they
have similar properties
In some groups, the elements all have
the same number of valence electrons
in their atoms
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Electrons & the Periodic Table
In atoms of
elements in
Groups 1 & 2,
the number of
valence
electrons
matches the
group number
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Electrons & the Periodic Table
In atoms of
elements in
Groups 13-18,
the number of
valence
electrons is 10
fewer than the
group number
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Electrons & the Periodic Table
Atoms of elements
in Groups 3-12, the
Transition Metals, do
not follow a general
rule
•In addition, helium atoms
only have 2 valence
electrons
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Why Do I Need the Periodic Table?
What Do You Think?
What similarities exist between
you and the other members of
your family? How about
between you and your
classmates?
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Grouping the Elements - Group 1
Group 1: Alkali Metals1 Valence Electron
© Fall 2005, Pflugerville ISD, 8th Grade
All metals
except
Hydrogen, the
Group 1
elements, are
the most
reactive.
Unit A: Chapter 3
Grouping the Elements - Group 1
Group 1: Alkali Metals1 Valence Electron
© Fall 2005, Pflugerville ISD, 8th Grade
This means that
the atoms of
these elements
are not stable and
will lend valence
electrons to other
atoms.
Unit A: Chapter 3
Grouping the Elements - Group 1
Group 1: Alkali Metals1 Valence Electron
These elements
are never found
uncombined in
nature.
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Grouping the Elements - Group 1
Alkali Metals
Compounds formed from
Alkali metals have many
uses for humans
•NaCl, or Sodium Chloride,
is table salt that is used to
season your food
•Potassium compounds
are found in bananas
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Grouping the Elements - Group 2
Group 2: Alkaline-Earth
Metals- 2 Valence Electrons
Alkaline-Earth
metals are
very reactive,
but not as
reactive as
Alkali metals.
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Grouping the Elements - Group 2
Group 2: Alkaline-Earth
Metals- 2 Valence Electrons
© Fall 2005, Pflugerville ISD, 8th Grade
This is because
it is harder for
their atoms to
lose 2 valence
electrons than
for the Alkali
metals to lose 1
Unit A: Chapter 3
Grouping the Elements - Group 2
Group 2: Alkaline Earth Metals
•Magnesium is mixed
with other metals to
make rims on cars.
© Fall 2005, Pflugerville ISD, 8th Grade
•Calcium is an
important part of the
compound that keeps
your bones and teeth
healthy.
Unit A: Chapter 3
Grouping the Elements
Groups 3-12
Groups 3-12: Transition Metals
Groups 3-12
do not have
individual
names.
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Groups 3-12
Groups 3-12
© Fall 2005, Pflugerville ISD, 8th Grade
Groups 3-12
are all
grouped
together as
the
Transition
Metals.
Unit A: Chapter 3
Groups 3-12
Groups 3-12
© Fall 2005, Pflugerville ISD, 8th Grade
The Transition
Metals are less
reactive than
Groups 1 & 2
because they don’t
lose their valence
electrons as easily.
Unit A: Chapter 3
Grouping the Elements
Silver and
Gold are
Transition
Metals.
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Grouping the Elements
Transition Metals
Iron, Cobalt, and Nickel, all
Transition Metals, are the only
elements known to produce a
magnetic field.
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Group 13
Group 13: Boron Group
The most
common
element from
Group 13 is
aluminum.
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Group 13
Aluminum was considered
more precious than gold
or silver until the 1880s,
when plentiful electricity
made it cheaper.
•Aluminum is used to
make cans, cars, and
airplanes.
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Group 14
Group 14: Carbon Group
The nonmetal
Carbon, in
Group 14, is
often found
uncombined in
nature.
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Group 14
Carbon forms both
diamonds and charcoal.
Carbon also forms a wide
variety of compounds
such as proteins, fats,
and carbohydrates, all
necessary for life on
earth.
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Group 15
Group 15: Nitrogen Group
Nitrogen, a gas
at room
temperature,
makes up about
78% of the air
you breathe.
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Group 15
Group 15: Nitrogen Group
Nitrogen from the
air is combined
with Hydrogen to
make fertilizer.
Fertilizer helps grow
the crops that feed
us all.
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Group 16
Oxygen, in Group 16, makes up
about 21% of the air you breathe.
Oxygen is very reactive, combining
with many other elements such as iron
and carbon.
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Group 16
Sulfur, another common
member of Group 16, is used
to make sulfuric acid for car
batteries.
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Group 17
Halogens are the very
reactive nonmetals in
Group 17.
They react easily because
their atoms only need to gain 1
electron to have a complete
set
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Group 17
Chlorine is a
yellow halogen
that is used to
disinfect water
for drinking
and swimming
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Group 18
Noble gases are unreactive
nonmetals in Group 18.
These elements’ atoms have full
outermost energy levels, and cannot
react with other elements
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Group 18
Noble gases like neon
glow when electrically
charged.
Argon in a light bulb
keeps the filament
from burning out.
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Let’s Review!
-1-
How does the periodic table
help you identify the physical
properties of elements?
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3
Let’s Review!
-2How are elements grouped on
the periodic table of
elements?
© Fall 2005, Pflugerville ISD, 8th Grade
Unit A: Chapter 3