6th Grade Science

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7th Grade
Chapter 3- Understanding the Periodic Table
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7th Grade Science
Chapter 3- Understanding the Periodic Table
PISD PowerPoint Lessons Developed By Ryan
Gross, Park Crest Middle School Edited By Kenn
Heydrick, Coordinator of Science Health
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Chapter 3 - Understanding the Periodic Table
Section 1 Electrons and the Periodic
Table Section 2 Grouping the Elements
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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?
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Electrons the Periodic Table

• Electrons in all atoms are arranged around the
  nucleus in regions called energy levels
• The largest atoms have as many as seven energy
  levels

Energy Levels
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Electrons the Periodic Table
The outermost energy level is called the valence
shell The electrons in the valence shell are
called valence electrons
Energy Levels
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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
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Electrons the Periodic Table
In atoms of elements in Groups 1 2, the number
of valence electrons matches the group number
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Electrons the Periodic Table
In atoms of elements in Groups 13-18, the number
of valence electrons is 10 fewer than the group
number
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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

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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?
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Grouping the Elements - Group 1
Group 1 Alkali Metals- 1 Valence Electron
All metals except Hydrogen, the Group 1 elements,
are the most reactive.
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Grouping the Elements - Group 1
Group 1 Alkali Metals- 1 Valence Electron
This means that the atoms of these elements are
not stable and will lend valence electrons to
other atoms.
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Grouping the Elements - Group 1
Group 1 Alkali Metals- 1 Valence Electron
These elements are never found uncombined in
nature.
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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

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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.
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Grouping the Elements - Group 2
Group 2 Alkaline-Earth Metals- 2 Valence
Electrons
This is because it is harder for their atoms to
lose 2 valence electrons than for the Alkali
metals to lose 1
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Grouping the Elements - Group 2
Group 2 Alkaline Earth Metals

• Magnesium is mixed with other metals to make rims
  on cars.
• Calcium is an important part of the compound that
  keeps your bones and teeth healthy.

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Grouping the ElementsGroups 3-12
Groups 3-12 Transition Metals
Groups 3-12 do not have individual names.
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Groups 3-12
Groups 3-12 are all grouped together as the
Transition Metals.
Groups 3-12
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Groups 3-12
The Transition Metals are less reactive than
Groups 1 2 because they dont lose their
valence electrons as easily.
Groups 3-12
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Grouping the Elements
Silver and Gold are Transition Metals.
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Grouping the Elements
Transition Metals
Iron, Cobalt, and Nickel, all Transition Metals,
are the only elements known to produce a magnetic
field.
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Group 13
Group 13 Boron Group
The most common element from Group 13 is aluminum.
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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.

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Group 14
Group 14 Carbon Group
The nonmetal Carbon, in Group 14, is often found
uncombined in nature.
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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.
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Group 15
Group 15 Nitrogen Group
Nitrogen, a gas at room temperature, makes up
about 78 of the air you breathe.
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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.
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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.
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Group 16

• Sulfur, another common member of Group 16, is
  used to make sulfuric acid for car batteries.

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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
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Group 17
Chlorine is a yellow halogen that is used to
disinfect water for drinking and swimming
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Group 18
Noble gases are unreactive nonmetals in Group
18. These elements atoms have full outermost
energy levels, and cannot react with other
elements
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Group 18
Noble gases like neon glow when electrically
charged. Argon in a light bulb keeps the filament
from burning out.
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Lets Review!

• 1 -
• How does the periodic table help you identify the
  physical properties of elements?

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Lets Review!

• 2 -
• How are elements grouped on the periodic table of
  elements?