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7th Grade
7th Grade Science
PISD PowerPoint Lessons
Developed ByRyan Gross, Park Crest Middle School
Edited ByKenn Heydrick, Coordinator of Science & Health
© Fall 2005, Pflugerville ISD, 8th Grade Unit A: Chapter 3
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 does your outer shell of clothing say to other people about you
and who you are?
What Do You Think?
© Fall 2005, Pflugerville ISD, 8th Grade Unit A: Chapter 3
Electrons & the Periodic Table
Energy Levels
Electrons in all atoms are arranged around the nucleus in regions called energy levels
•The largest atoms have as many as seven energy levels
© Fall 2005, Pflugerville ISD, 8th Grade Unit A: Chapter 3
Electrons & the Periodic Table
Energy Levels
The outermost energy level is called the valence shell
The electrons in the valence shell are called valence electrons
© Fall 2005, Pflugerville ISD, 8th Grade 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 similarities exist between you and the other members of
your family? How about between you and your
classmates?
What Do You Think?
© Fall 2005, Pflugerville ISD, 8th Grade Unit A: Chapter 3
Grouping the Elements - Group 1
Group 1: Alkali Metals-1 Valence Electron All metals
except Hydrogen, the Group 1 elements, are the most reactive.
© Fall 2005, Pflugerville ISD, 8th Grade Unit A: Chapter 3
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.
© Fall 2005, Pflugerville ISD, 8th Grade Unit A: Chapter 3
Grouping the Elements - Group 1
Group 1: Alkali Metals-1 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 This is because
it is harder for their atoms to lose 2 valence electrons than for the Alkali metals to lose 1
© Fall 2005, Pflugerville ISD, 8th Grade 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.
•Calcium is an important part of the compound that keeps your bones and teeth healthy.
© Fall 2005, Pflugerville ISD, 8th Grade Unit A: Chapter 3
Grouping the ElementsGroups 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 Groups 3-12 are all grouped together as the Transition Metals.
© Fall 2005, Pflugerville ISD, 8th Grade Unit A: Chapter 3
Groups 3-12
Groups 3-12 The Transition Metals are less reactive than Groups 1 & 2 because they don’t lose their valence electrons as easily.
© Fall 2005, Pflugerville ISD, 8th Grade 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!
- 2 -
How are elements grouped on the periodic table of
elements?